The Handbook of C-Arm Fluoroscopy-Guided Spinal Injections

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Author: M.D. | Ph.D. | Linda Hong Wang | M.D. | Anne Marie McKenzie-Brown | M.D. | Allen Hord

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THE HANDBOOK OF C-ARM FLUOROSCOPY-GUIDED SPINAL INJECTIONS

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HANDBOOK OF C-ARM FLUOROSCOPY-GUIDED SPINAL INJECTIONS Linda hong wang Anne Marie McKenzie-Brown Allen H. Hord

Boca Raton London New York

A CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa plc.

Published in 2006 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2006 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8493-2254-5 (Hardcover) International Standard Book Number-13: 978-0-8493-2254-9 (Hardcover) Library of Congress Card Number 2005051403 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Wang, Linda H. (Linda Hong) Handbook of C-arm fluoroscopy-guided spinal injections / Linda H. Wang, Anne Marie McKenzieBrown, Allen Hord. p. cm. Includes bibliographical references and index. ISBN 0-8493-2254-5 (alk. paper) 1. Injections, Spinal--Handbooks, manuals, etc. 2. Diagnosis, Fluoroscopic--Handbooks, manuals, etc. 3. Spine--Puncture--Handbooks, manuals, etc. 4. Chronic pain--Treatment--Handbooks, manuals, etc. I. McKenzie-Brown, Anne Marie. II. Hord, Allen. III. Title. RC400.W32 2006 615'.6--dc22

2005051403

Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com Taylor & Francis Group is the Academic Division of T&F Informa plc.

and the CRC Press Web site at http://www.crcpress.com

Dedication To our spouses, without whose love, support, and patience this handbook would not have been possible. To our children, anything is possible if you put your mind and heart to it. To our parents, who taught us to believe in ourselves, to aim past the limits, to never give up, and to make each day count.


Acknowledgments To Dr. James R. Zaidan, our department chairman, and Dr. Peter Sebel, our vice chairman, for believing in and supporting us, as well for their dedication to graduate medical education. To Dr. Jay Johansen for the many hours that he dedicated to helping us with the computer software that made possible the images used throughout this book. To Drs. Randy Rizor, John Porter, and Charles McNeill for teaching spinal injections. To Ms. Rochelle Lewis, who was a great help with proofreading. To Mr. Jeannette Ramos, whose tireless dedication helps to make our practice run smoothly. To Mrs. Sophia Rosene whose mastery of x-ray skills proved invaluable. To former and current pain fellows, with particular thanks to Dr. Talal Khan and Dr. Brannon Frank, for special assistance in the fluoroscopy images and computer editing. Your pursuit of knowledge was instrumental in our academic growth as well. To our pain colleagues, Drs. Patricia Baumann and Michael Byas-Smith, for supporting us in this project. And perhaps last, but certainly not least, to our patients, who give us their trust and, occasionally, restore our faith in ourselves.


Preface C-arm fluoroscopy-guided spinal injections have been performed widely for diagnosis and management of spine and para-spinal-related pain disorders. So often, residents and pain fellows do not receive formal training in radiography and the related anatomy of the vertebral column. The purposes of this handbook are to (a) illustrate spinal injections in a step-by step fashion, (b) present fluoroscopy imaging and related spinal anatomy, and (c) describe manipulation of C-arm fluoroscopy to get ideal images for spinal injections. The concept of this book started off as a compilation of notes and lectures that were put together for the educational benefit of our pain fellows as well as those residents who rotate on the pain service. The residents spend 2 months on the service and often have a difficult time orienting themselves to the C-arm and the resulting fluoroscopic images. While there are now quite a few books on the market that show the final needle position for spinal injections, we felt that there was a need for a book describing a more basic, step-by-step approach to spinal injections. As a pain fellow, Dr. Linda Wang started collecting images and teaching tools to help her better understand the reasoning behind the fluoroscopic images that were used for spinal injections. As a faculty member, Dr. Wang spent a tremendous amount of time studying the relationships between the skeletal model, the matching fluoroscopic image, and the desired needle placement in the cervical, lumbar, and sacral spinal regions. There is often a skeleton hanging prominently in the procedure room that is used as a reference when we perform fluoroscopically guided injections. Dr. Wang sought to recreate those images in her chapters that effectively demonstrate the relationships between the angle of the x-ray beam and the spinal column. In the chapters describing the fluoroscopic imaging of the cervical, lumbar, and sacral spine, Dr. Wang describes in detail how the trainee would go about obtaining the views needed to approach the spine at each level. Dr. McKenzie-Brown has long had an interest in the cervical spine and procedures performed around the cervical spine as well as in lumbar discography. The neck houses critical vascular structures that affect the way in which injections around the cervical spine are performed. The chapters that she wrote pertaining to cervical injections show a safe method for performing these injections under fluoroscopy. As our program became more interventional in the management of pain, Dr. McKenzie-Brown became more interested in radiation safety, and the basic tenets of radiation safety are succinctly described in Chapter 3. Finally, the sympathetic chapters are left as a category unto themselves. Until fairly recently, stellate and lumbar sympathetic injections were routinely performed without fluoroscopy. Dr. Wang takes us through step-by-step approaches to each of the sympathetic blocks with insights into how to ascertain the correct needle position at each level. Dr. Wang was encouraged by Dr. Allen H. Hord to enter the area of pain medicine. Dr. Hord served as a motivator and educator in the training of Dr. Wang and countless other physicians in the area of C-arm fluoroscopic techniques. His review of this handbook proved to be an invaluable asset.

Each of the spinal injections in this handbook is simply written. The preferred patient’s position as well as C-arm fluoroscopy position, preferred fluoroscopic images, and related anatomic structures on the spine are described. The steps taken to get to the final placement of the needle tip are also described. Not only are the correct needle placements illustrated from different views of the spine, but possible incorrect needle placements are shown as well. We endeavored to provide a handbook that will become a useful teaching aid for residents and fellows striving to improve their skills in the performance of spinal injections for pain management.

The Authors Linda Hong Wang, M.D., Ph.D., graduated from Capital University of Medical Sciences (Beijing Second Medical College) in Beijing, China. She then came to the United States and studied basic science in pain medicine at the University of Illinois in Chicago. After she received her Ph.D., she continued her training in anesthesia at the Mayo Clinic in Rochester, Minnesota. She completed her anesthesiology residency at Emory University School of Medicine, following which she spent 12 additional months there in her pain fellowship. She is currently working in Emory’s Department of Anesthesiology in Atlanta, Georgia.

Anne Marie McKenzie-Brown, M.D., graduated from Johns Hopkins School of Medicine and completed her anesthesiology residency at Emory Healthcare. After spending a year in pain fellowship training at the Johns Hopkins Department of Anesthesiology, she returned to Emory Department of Anesthesiology, where she remains on faculty. She is currently the director of the Division of Pain Medicine and the director of the Pain Fellowship Program at the Emory Department of Anesthesiology in Atlanta, Georgia. Dr. McKenzie-Brown earned her undergraduate degree in chemistry at the University of Virginia in Charlottesville. She went to Baltimore and completed her doctorate of medicine at Johns Hopkins School of Medicine. After completing a year of internship in internal medicine at St. Luke’s/Roosevelt Hospital, she came to Atlanta and completed an anesthesiology residency at the Emory Department of Anesthesiology. She then returned to Baltimore and spent 1 year in the Department of Anesthesiology and Critical Care in fellowship training in pain medicine and as an assistant in the Division of Regional Anesthesia. Following that, she came back to Atlanta as a staff anesthesiologist in the Emory Department of Anesthesiology, dividing her time between clinical anesthesiology and pain medicine. She was the director of the Grady Pain Clinic between 1995 and 2003, the clinical director of the Emory Center for Pain Medicine in 2002, and the division director of Pain Medicine the following year. In 2004, she became the program director for the Emory Pain Fellowship. Dr. McKenzie-Brown is board certified in anesthesiology and earned the Certificate of Additional Qualifications in Pain Management. She is also board certified by the American Board of Pain Medicine. Her interests include spinal pain, with special interest in cervical spinal pain and sacroiliac joint pain.

Allen H. Hord, M.D., is a practicing pain consultant with Pain Consultants of Atlanta. He also holds an adjunct appointment as clinical associate professor of anesthesiology at Emory University School of Medicine in Atlanta, Georgia. Dr. Hord earned his B.A. in chemistry and molecular biology at Vanderbilt University in Nashville, Tennessee, and his M.D. at the University of Kentucky School of Medicine in Lexington, Kentucky. After graduating, he completed his internship at Grady Memorial Hospital in Atlanta, Georgia, and his residency in anesthesiology at Emory University School of Medicine. His fellowship in pain was conducted at the University of Cincinnati Pain Control Center in Cincinnati, Ohio. He is certified by the American Board of Anesthesiology and was awarded a Certificate of Added Qualifications in Pain Management. Dr. Hord is also certified by the American Board of Pain Medicine. Dr. Hord was formerly director of the Center for Pain Medicine, director of the Division of Pain Medicine, and program director of the Pain Management Fellowship at Emory University School of Medicine. Dr. Hord’s current research is devoted to the study of neuropathic pain. He has authored and coauthored more than 62 articles, abstracts, editorials, books, book chapters, book reviews, review articles, and case reports concerning topics in pain management.

Table of Contents Chapter 1.

An Introduction to Spinal Injections.....................................................1

Chapter 2. Basic Radiographic Background of the Vertebral Column ...................5 C-Arm Fluoroscopy and Images........................................................................................................7 Axial Skeleton..................................................................................................................................13 Anatomy of a Typical Lumbar Vertebra ....................................................................................15 Pelvic Girdle and Sacrum ...........................................................................................................17 Classification of Bones and Typical Fluoroscopic Images of Bones .............................................18 Bibliography.....................................................................................................................................27 Chapter 3. Radiation Safety ................................................................................29 Quantification of Radiation Exposure .............................................................................................31 Steps to Minimize Radiation Exposure ...........................................................................................32 Shielding...........................................................................................................................................39 Bibliography.....................................................................................................................................39 Chapter 4. Basic Steps for Spinal Injections .......................................................41 Bibliography.....................................................................................................................................54 Chapter 5. Fluoroscopic Images of the Lumbar Spine ........................................55 Positioning the Patient .....................................................................................................................57 Anterior/Posterior View of the Lumbar Spine ................................................................................57 Oblique View of the Lumbar Spine.................................................................................................59 Lateral View of the Lumbar Spine ..................................................................................................62 Suggestions on How to Check the Needle Depth...........................................................................67 Bibliography.....................................................................................................................................69 Chapter 6. Lumbar Spinal Injections ...................................................................71 Lumbar Spinal Injections.................................................................................................................73 Lumbar Medial Branch Block .........................................................................................................73 Lumbar Medial Branch Denervation ..........................................................................................87 Lumbar Transforaminal Epidural Steroid Injection ........................................................................88 Special Considerations of Oblique Views ..................................................................................94 Rules for Getting Oblique Views of the Lumbar Spine..................................................................95 Lumbar Transforaminal Epidural Steroid Injection at the Level of L5/S1 .....................................................................................................................111 Lumbar Discography......................................................................................................................124 Introduction ...............................................................................................................................124

Manometry .....................................................................................................................................127 Patient Preparation ....................................................................................................................127 Sedation .....................................................................................................................................127 Preparation for Needle Placement .......................................................................................128 Patient Position..........................................................................................................................128 C-Arm Position .........................................................................................................................129 Needle Placement......................................................................................................................130 Potential Difficulties with Needle Placement (Annular Placement of the Needle) ..........................................................................................132 Contrast Injection within the Disc Space .................................................................................136 Mechanically vs. Chemically Sensitive Discs ..........................................................................141 Discography at L5/S1 ....................................................................................................................141 Positioning C-Arm Fluoroscopy ...............................................................................................142 Needle Insertion ........................................................................................................................142 Confirming the Needle Placement ............................................................................................145 Injecting Contrast ......................................................................................................................146 Post-Procedure ...............................................................................................................................147 Bibliography...................................................................................................................................148 Chapter 7. Fluoroscopic Images of the Cervical Spine .....................................151 Positioning the Patient ...................................................................................................................153 Positioning the C-Arm Fluoroscopy..............................................................................................154 A/P (P/A) View and Lateral View of the Cervical Spine .............................................................155 Comparison of Cervical Vertebrae and Lumbar Vertebrae ...........................................................156 Lateral and Oblique Views of the Cervical Spine.........................................................................158 Cervical Intervetrebral Foramina and the Cervical Spinal Nerve Roots ......................................165 Bibliography...................................................................................................................................167 Chapter 8. Cervical Injections ...........................................................................169 Preparation for the Performance of Cervical Injections ...............................................................171 Cervical Facet Injections ...............................................................................................................172 Intra-Articular Facet Injections......................................................................................................174 C1/C2 Joint Injection ................................................................................................................174 C2/C3 to C6/C7 Intra-Articular Joint Injections ......................................................................180 Cervical Medial Branch Injections ...........................................................................................186 Cervical Medial Branch .................................................................................................................191 Radiofrequency Denervation.....................................................................................................191 Radiofrequency Denervation: (C3 to C8) Medial Branches ....................................................192 Cervical Epidural and Selective Nerve Root Injections................................................................196 Cervical Transforaminal Injections...........................................................................................196 C2 Dorsal Root Ganglion Injection..........................................................................................198 C3 to C7 Transforaminal Injections .........................................................................................201 Selective Nerve Root Injection or Epidural Steroid Injection .................................................210 Interlaminar Epidural Steroid Injections ..................................................................................216 Bibliography...................................................................................................................................218 Chapter 9. Fluoroscopic Images of the Sacrum and Pelvis...............................221 Posterior View of the Pelvis and the Sacrum................................................................................223 A/P View of Fluoroscopic Image of the Sacrum ..........................................................................224 Bibliography...................................................................................................................................228

Chapter 10. Pelvic and Sacral Injections...........................................................229 Sacroiliac Joint Injection ...............................................................................................................231 Caudal Epidural Steroid Injection .................................................................................................238 Bibliography...................................................................................................................................246 Chapter 11. Sympathetic Blocks.......................................................................247 Stellate Ganglion Block (Right Side)............................................................................................249 Lumbar Sympathetic Block ...........................................................................................................253 Superior Hypogastric Plexus Block...............................................................................................261 Bibliography...................................................................................................................................267 Index...............................................................................................................................................269


Chapter

An Introduction to Spinal Injections

1

1


An Introduction to Spinal Injections

3

In 1994, the International Association for the Study of Pain (IASP) defined pain as “an unpleasant sensory and emotional experience associated with actual or potential damage or described in terms of such damage.” Spinal pain is still a leading cause of disability in the industrialized world. Spinal injections are common procedures for both the diagnosis and treatment of pain related to the spine. This book utilizes a step-by-step approach to illustrate routinely performed fluoroscopically guided spinal injections and procedures at the cervical, thoracic, and lumbosacral regions. This is done in an attempt not only to introduce trainees to the basic interventional techniques but also to assist instructors in their pursuit of demonstrating the techniques of spinal injections in a clear and simple manner. All of the commonly performed spinal injections involve placing the needle in or around the vertebral column. Mastery of the technique of spinal injections involves learning where along the spine to place the needle. Figure 1.1 and Figure 1.2 demonstrate the wide variety of spinal injections that are commonly performed in pain practices. Figure 1.1 represents the axial view, while Figure 1.2 shows the oblique view of the spinal column. Transforaminal epidural steroid injection

Medial branch block

Interlaminar epidural steroid injection Discography

Lumbar sympathetic block FIGURE 1.1 Axial view of needle placements for spinal injections.

Handbook of C-Arm Fluoroscopy-Guided Spinal Injections

4

Transforaminal epidural steroid injection

Intraarticular facet injection

Medial branch block

Lumbar sympathetic block Discography

Interlaminar epidural steroid injection

FIGURE 1.2 Oblique view of needle placements for spinal injections.

We will guide readers in a step-by-step fashion through injections commonly performed around the cervical spine, including intra-articular cervical facet and medial branch injections, radiofrequency ablations, and cervical transforaminal and interlaminar epidural steroid injections. Chronic pain is among the most common forms of low back pain that we entcounter in our practice. We will help readers to understand the details of commonly performed lumbar spinal injections, such as lumbar media branch block and transforaminal epidural steroid injection. The more commonly performed procedures in the sacral region that we will discuss include sacroiliac and caudal injections. We will also describe commonly performed sympathetic blocks including stellate ganglion blocks, lumbar sympathetic blocks, and performance of the superior hypogastric plexus block.

Chapter

Basic Radiographic Background of the Vertebral Column

2

5



7

It is essential to be familiar with fluoroscopic images and related anatomy of the human vertebral column in order to perform spinal injections. In this chapter we will go over basic fluoroscopic images of human bones, including human vertebrae.

C-Arm Fluoroscopy and Images A C-arm fluoroscope consists of an x-ray tube, a C-arm arch, an image intensifier, a control panel with a footswitch, and a computerized image display system (Figure 2.1). In C-arm fluoroscopy, a fluoroscopic beam, usually coming from below, penetrates the spine, sending an image to the intensifier. The image is then displayed on a TV screen for review (Figure 2.2). The C-arm can be rotated in different directions in order to view an object from different angles (Figure 2.3). The control panel allows us to adjust how images are generated and displayed by pressing function keys. The footswitch, also part of the control panel, offers more flexibility. The image system not only displays fluoroscopic photos but also stores fluoroscopic images for review and comparison.

Intensifier

Image display system

Control panel

Footswitch FIGURE 2.1 Photograph of a C-arm.

X-ray tube


8

A short bone

The short bone is placed between the x-ray tube and the intensifier

The fluoroscopic photo is displayed on the TV screen

A fluoroscopic image of the short bone

FIGURE 2.2


FIGURE 2.3 C-arm rotations.

9

10


A photograph (Figure 2.4) and a fluoroscopic image (Figure 2.5) are both two-dimensional pictures. However, each has striking differences. Because our goal is to inject appropriate medications in or around the target areas of the spine, it is essential to understand the fluoroscopic images of the spine and the relationship between needle placement and the target area.

FIGURE 2.4 Regular picture of the spine, anterior view.

FIGURE 2.5 Fluoroscopic photo of the lumbar spine.


11

A fluoroscopic image of a cylinder from the side, for example (Figure 2.6), is a rectangularshaped image regardless of the angle of the beam. We cannot view the cylinder from the ends. The TV screen of C-arm fluoroscopy is only able to display one image at a time. By reviewing a series of images of this object (Figure 2.7), we are able to mentally construct a three-dimensional picture of this cylinder.

X-ray tube

A cylindrical object FIGURE 2.6 Fluoroscopy does not show a 3-D picture.

X-ray tube

X-ray tube

A cylindrical object X-ray tube

FIGURE 2.7 Creating 3-D images mentally.


12

If the fluoroscopic beam goes through a cube (Figure 2.8), the TV screen displays a square. However, we are unable to identify the properties of this cube.

A cube

A fluoroscopic image of the cube

FIGURE 2.8

If a cylinder is placed on top of the cube, a fluoroscopic picture is merely a square with a circle in the middle (Figure 2.9). We are unable to judge the exact relationship between the cylinder and the cube.

A cylindrical object A cube

A fluoroscopic image of the cylindrical object and the cube FIGURE 2.9


13

A fluoroscopic picture of these objects (Figure 2.10) is complicated. We cannot describe their exact relationships without adding another picture of these objects from a different view.

A fluoroscopic image of three objects

FIGURE 2.10

The basic steps of a fluoroscopy-guided spinal injection include the following (see Chapter 4 for details): 1. 2. 3. 4. 5.

Identifying a target point in the area of the spine or the pelvis Obtaining fluoroscopic images Inserting a needle Verifying correct needle placement by using the fluoroscopic images Injecting the appropriate medication into the target area

It is important to review the anatomy of the vertebral column and the anatomy of the pelvic girdle.

Axial Skeleton There are 206 separate bones that form the adult human skeletal system — the framework of the entire human body. The adult skeletal system is divided into the axial skeleton and the appendicular skeleton. The axial skeleton has a total of 80 bones that lie on or near the central axis of the human body, including the skull, vertebral column, ribs, and sternum. The vertebral column (Figure 2.11) consists of 26 vertebrae and includes 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 1 sacrum, and 1 coccyx.


14

Axial skeleton (total 80 pieces) — Skull — Hyoid — Auditory ossicles • Cervical (7)

— Vertebral column

• Thoracic (12)

— Thorax

• Lumbar (5) • Sacrum (1) • Coccyx (1)

FIGURE 2.11

There are 126 separate bones in the appendicular skeleton (Figure 2.12).

— — — —

FIGURE 2.12

Shoulder girdle Upper extremities Pelvic girdle Lower extremities

•

Hip bone (2)


15

Anatomy of a Typical Lumbar Vertebra A typical vertebra consists of the vertebral body and the vertebral ring (Figure 2.13 through Figure 2.17). Each vertebral body is roughly cylindrical in shape and is connected to the vertebral arch by the pedicle on each side. The vertebral arch is composed of two pedicles, two laminae that are fused at the midline and extend a spinous process posteriorly, two superior articular processes, two inferior articular processes, and two transverse processes. In the vertebral column, the superior vertebral notch and the inferior vertebral notch form the intervertebral foramina through which spinal nerves and blood vessels traverse. The inferior articular process and the superior articular process on each side form a joint called a zygapophyseal joint. The zygapophyseal joint is most frequently called a facet. These pictures of the lumbar vertebra are essential to the understanding of the interpretation of fluoroscopic images necessary for appropriate needle placement. Figure 2.13 to 2.17: (1) Vertebral body; (2) pedicle; (3) lamina; (4) spinous process; (5) superior vertebral notch; (6) inferior vertebral notch; (7) superior articular process; (8) inferior articular process; (9) transverse process.

1

1

2

2

4

3

4 7

9

7 1

4

1

2

2 2

1

3

4 9

9

4

FIGURE 2.13 Superior/oblique view of the lumbar vertebrae.

7

5

2 4

8 FIGURE 2.14 Lateral view of the lumbar vertebra.

6

1


16

7

9 3 4

6 8

FIGURE 2.15 Oblique view of the lumbar vertebra.

7

3 4 9

8

FIGURE 2.16 Posterior view of the lumbar vertebra.

1 9

FIGURE 2.17 Anterior view of the lumbar vertebra.


17

Pelvic Girdle and Sacrum Spinal injections involving the areas of the pelvic girdle and the sacrum include sacroiliac joint injections, caudal epidural steroid injections, sacral transforaminal injections, and so forth. Therefore, we need to be familiar with some anatomic structures of the pelvic girdle and the sacrum (Figure 2.18 through Figure 2.20). 5

5

FIGURE 2.18 Lateral view of pelvis and sacrum; (5), posterior superior iliac spine.

4 5

5

5

1

2

3

2

3

FIGURE 2.19 Posterior view of the pelvis. (1) Posterior sacral foramina, (2) sacral cornu, (3) sacral hiatus, (4) superior articular process, (5) posterior superior iliac spine.


18

Classification of Bones and Typical Fluoroscopic Images of Bones Each of the 206 bones of the human body can be classified according to its shape (Figure 2.20 through Figure 2.24): long bone, short bone, flat bone, or irregular bone. It is not difficult to understand a typical fluoroscopic image of a long bone, a short bone, or a flat bone (Figure 2.20 through Figure 2.22).

FIGURE 2.20 Long bone: radius and its fluoroscopic photo.

FIGURE 2.21 Short bone: first phalange and its fluoroscopic photo. A rib shadow

patella

FIGURE 2.22 Flat bones: patella and rib and their fluoroscopic photos.


19

However, it is difficult to identify anatomic structures on fluoroscopic images of irregular bones (Figure 2.23).

FIGURE 2.23 Irregular lumbar bone: vertebra and facial bones and their fluoroscopic photos.

It is also easy to visualize a fluoroscopic image of two overlapping bones (Figure 2.24), although this image cannot show the exact relationship between them. And, we cannot judge the spatial relationship between these bones.

FIGURE 2.24 Fluoroscopic photo of a rib on top of the patella.

The outer shell of most bones is composed of hard or dense bone tissue known as compact bone (Figure 2.25). The shaft of a long bone, and possibly of a short bone, is hollow, and it is called the medullary cavity. In the adult, this cavity usually contains fatty yellow marrow.


20

Compact Bone

Bone marrow FIGURE 2.25

Each vertebra is an example of an irregular bone. We will consider the fact that each vertebra is built up by several blocks (pieces of flat bones and short bones) (Figure 2.26). The lamina, for example, is a flat block — a flat bone similar to a piece of the rib. Each pedicle, a Latin term meaning “little foot,” is a small block with a cylindrical shape (a piece of short bone) pointing out from the vertebral body posteriorly on each side. Let us illustrate how to “build a typical lumbar vertebra” using building blocks in order to understand the typical fluoroscopic image of a lumbar vertebra.

Spinous process Superior articular process

Lamina Pedicle

Transverse process Inferior articular process Vertebral body FIGURE 2.26


21

An x-ray beam penetrates a patient in a prone position. A typical anterior–posterior (A/P) fluoroscopic image of a single lumbar vertebra is shown in Figure 2.27.

Patient in a prone position

A fluoroscopic photo of anterior-posterior view (A/P view) of a single lumbar vertebra

X-Ray tube

FIGURE 2.27

In order to understand how to get an A/P-view fluoroscopic image of a single lumbar vertebra, we must first take apart a lumbar vertebra (Figure 2.28).

X-ray tube

X-ray

FIGURE 2.28


22

Figure 2.29 illustrates how to create a two-dimensional A/P fluoroscopic image of the lumbar vertebral body with two pedicles only. The two-dimensional picture of the lumbar vertebral body is a rectangle, and the two-dimensional picture of each pedicle is a circle. 2-D image of vertebral body shadow

2-D image of pedicle shadow

2-D image of vertebral body shadow Pedicles

X-ray tube

FIGURE 2.29

X-ray tube


23

A two-dimensional image of the vertebra is like a puzzle. A two-dimensional image of each piece of the vertebra is a single puzzle piece (Figure 2.30). 2-D image of spinous process

2-D image of inferior articular process

2-D image of lamina

2-D image of superior articular process

2-D image of transverse process

2-D image of vertebral body 2-D image of pedicles

X-ray X-ray FIGURE 2.30

24


Taking an A/P fluoroscopic image of a single lumbar vertebra is like putting the pieces of the vertebra back together (Figure 2.31). A two-dimensional image of the pedicles and the vertebral arch, including the lamina, the spinous process, the superior and inferior processes, and the transverse processes, brings together a unique puzzle picture (Figure 2.31).

X-ray

FIGURE 2.31


25

An A/P fluoroscopic image of a single lumbar vertebra or multiple vertebrae is illustrated in Figure 2.32 and Figure 2.33. The two-dimensional image of pedicles is shown in the fluoroscopic images but not in regular photos of vertebrae. 2 6 5

2

3 4

6 5 3

4

2

2

1

1

1 3 5

4

1

6

6 5

4 3

FIGURE 2.32 (1) Pedicles, (2) superior articular process, (3) spinous process, (4) inferior process, (5) lamina, and (6) transverse process.


26

1

2 2 6 3

5

3

4

4

2

2

6

6

5

1

6 3

5

1 5

3

4

4

FIGURE 2.33 (1) Pedicles, (2) superior articular process, (3) spinous process, (4) inferior process, (5) lamina, and (6) transverse process.


27

Bibliography Bontrager, K.L. and Anthony, B.T., Eds., Textbook of Radiographic Positioning and Related Anatomy, 2nd ed., C.V. Mosby Company, St. Louis, MO, 1990. Brown, D.L., Ed., Atlas of Regional Anesthesia, 2nd ed., W.B. Saunders, Philadelphia, 1999. Clemente, G.D., Ed., Gray’s Anatomy, 13th ed., Lea & Febiger, Philadelphia, 1984. Fenton, D.S. and Czervionke, L.F., Eds., Image-Guided Spine Intervention, W.B. Saunders, Philadelphia, 2003. Netter, F.H., Ed., Atlas of Human Anatomy, Ciba Geigy Corporation, 1989. Waldman, S.D., Ed., Atlas of Interventional Pain Management, 2nd ed., W.B. Saunders, Philadelphia, 2004.


Chapter

Radiation Safety

3

29


Radiation Safety

31

As pain medicine becomes increasingly interventional, the use of fluoroscopy has become more prevalent in the performance of spinal and other injections for the diagnosis and relief of chronic pain. Fluoroscopy is even being used, in some instances, in the performance of peripheral injections, e.g., piriformis muscle injections for chronic pain. A basic understanding of radiation safety is an important part of the pain practitioner’s knowledge base, as it facilitates optimal care for our patients. While some of the spinal injection procedures described in this book may also be performed under computed tomography (CT) guidance, all of the procedures described are performed under fluoroscopic guidance; specifically, fluoroscopy using a C-arm. This chapter will briefly review practical safety concepts to minimize the risk of complications from exposure to ionizing radiation. Ionizing radiation can come from x-rays or gamma rays; the radiation being referred to in this chapter is due to x-rays. While gamma rays naturally occur from radioactive atoms, x-rays are those that we deal with in clinical practice — those that are emitted from machines. The principles of fluoroscopy for pain procedures include maximizing patient benefit while minimizing risk to both patient and staff using the ALARA (as low as reasonably achievable) principle. The routine use of fluoroscopy has dramatically increased with the rise in procedures performed by interventional radiologists, cardiologists, and pain physicians. Approximately 500,000 or more procedures for chronic pain are performed annually under fluoroscopic guidance.1 The fluoroscopically guided procedures performed by pain physicians utilize relatively lower amounts of fluoroscopy time in comparison to the other fluoroscopically guided therapeutic procedures, e.g. coronary angioplasty, transjugular intrahepatic portosystemic shunts, and so forth. The vast majority of procedures performed by pain practitioners are generally performed within 1 to 2 min or less of fluoroscopy time, even at teaching facilities. The exposure of physicians to scatter decreases with increased experience.2

Quantification of Radiation Exposure When a human body is exposed to ionizing radiation, there is an interaction with the human atoms that results in energy transfer (absorption). The absorbed dose is the quantity used to evaluate the amount of radiation energy that is deposited into an absorbing medium, for example, human tissue.1 This absorbed dose is described in gray (Gy) units (International System) or the older radian (rad) units (United States). One gray (1 J/kg) is equivalent to 100 rad. Rem (rad equivalent man) is a unit of exposure, vs. Gy, which is a unit of energy. Rem is monitored using the radiation badges worn by hospital personnel. One rem is equivalent to 0.01 sievert (Sv). The annual limits of exposure to health care workers are 5000 mrem to the body; 15,000 mrem to the lens; and 50,000 mrem to the extremities. This does not include the amount of radiation calculated for natural exposure associated with everyday living as well as routine dental examinations. In 1994, the Center for Devices and Radiological Health of the U.S. Food and Drug Administration (FDA) issued an advisory3 cautioning physicians to be aware of the potential for adverse effects to patients who have been exposed to prolonged periods of fluoroscopy. As the skin entry site of the beam is the most susceptible to injury, the advisory stated that skin injury may result after less than 1 h of fluoroscopy, even at typical dose rates. This is far in excess of the fluoroscopic time used for even the most challenging pain procedures. The effects described may not be seen for weeks after radiation exposure. The radiation safety officer of the hospital is a valuable resource for more information on this subject. While performing procedures under fluoroscopy, the goal is to minimize the absorbed dose to the skin and to reduce radiation scatter from the patient to the physician and the staff. Typically, the skin absorbs radiation at a rate of 2 to 5 rad/min. Radiation injury to the skin occurs at the following approximate thresholds4:


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3 Gy (300 rad): temporary epilation (hair removal by the roots) 6 Gy (600 rad): erythema 15 to 20 Gy (1500 to 2000 rad): desquamation, dermal necrosis, and ulceration

Most fluoroscopically guided spinal injections performed by pain physicians are done using a C-arm (Figure 3.1). This provides the benefit of rotating the image to oblique views without having to reposition the patient once the needle is in place. The beam is generated in the x-ray tube, passes through the patient, where it is detected in the image intensifier, and results in a two-dimensional image displayed on the monitor screen. The image intensifier converts the x-ray beams to light energy, producing a clearer image. A lateral view is needed in order to determine the needle depth in addition to the A/P angle view for accurate needle placement. Note that the A/P view is with respect to the patient, not to the procedure table. This is particularly relevant when an A/P view is needed in a patient with scoliosis. This will be discussed in more detail in future chapters.

1

3

2

FIGURE 3.1 Diagram of the C-arm and its components. The arrow pointing from the tube represents the emitting beam of x-rays going through the patient. Note that the image intensifier (above the patient) is as close to the patient as possible. (1) Image intensifier, (2) x-ray tube, (3) prone patient.

Steps to Minimize Radiation Exposure There are steps that pain practitioners can take to minimize radiation exposure to the patient and to the staff: 1. 2.

Use the last image hold to keep the last image seen on the screen and allow the physician to determine the next needle adjustment based on that image. Use the pulsed mode to greatly decrease exposure to the patient. Pulsed mode allows for the emission of short pulses of the beam, resulting in fewer frames per second, which substantially reduces the

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emitted dose when compared to nonpulsed fluoroscopy. In some instances, the radiation exposure may be reduced up to 75%.5 This may take some time to get accustomed to initially, as the image appears somewhat fractionated and is less clear, but the benefits in exposure reduction are substantial. 3. Keep the image within the patient’s body limits. Whenever possible, do not include areas outside of the body habitus when imaging the spine. 4. Use collimation to reduce the size of the x-ray field. This often sharpens the image while reducing scatter. It also helps to keep the main focus of the image in the center of the field; laser markers are also helpful in accomplishing this goal. It is best to keep collimation as tightly around the field of interest as possible to avoid scatter. Remember, scatter from the patient is a major source of exposure to the pain physician. Collimation assists in keeping the image completely within the body habitus of the patient. Note that there are two types of collimation: a. Leaf (linear) collimation (Figure 3.2): This is actually not collimation but a filter. This is helpful in cervical procedures, as it keeps the beam within the patient’s body mass. This is particularly helpful for patients with slender necks. b. Iris (circumferential) collimation (Figure 3.2): This cones down the image to the center of the screen. (See Figure 3.4 for an example of an image taken without collimation.)

FIGURE 3.2 Leaf (linear) collimation.

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FIGURE 3.3 Iris (circumferential) collimation.


Radiation Safety

FIGURE 3.4 No collimation was used with this image. Note the bright areas where the beam extends outside the patient’s frame.

35


36 5.

6.

7.

8.

9.

10. 11.

12.

13.

14.

Whenever possible, intermittent fluoroscopy should be used to minimize exposure time, as radiation dose is directly related to exposure time. Avoid using continuous fluoroscopy, e.g., in obtaining an oblique view of the spine. There is a direct relationship between the amount of radiation exposure (time) and the dose received by the patient and the scatter exposure to the physician.3 This is the aspect of fluoroscopy that is most easily controlled by the physician. As the radiation comes from the x-ray tube, it is best to have the image intensifier as close to the patient as possible. The closer the beam is to the patient, the greater the exposure to the patient. Realize that the exposure decreases with the square of the distance from the beam. Thus, being twice as far away from the source decreases the exposure by a factor of four. The physician should avoid placing any part of his or her body between the x-ray tube (or beam) and the patient. From this principle, it also stands that the farther away from the beam the physician or health care worker is, the lower the exposure. When positioned to perform the block, it is best to be closer to the image intensifier than to the x-ray tube. This becomes difficult with the lateral view in both cervical and lumbar procedures, and special attention should be paid to the position of the physician with regard to the x-ray tube. Realize that the greatest radiation exposure to the physician is due to scatter that is reflected off the patient to the physician. a. Inject contrast via extension tubing and under collimation to keep the physician’s hands out of the beam. If guiding of the needle needs to be done under “live fluoroscopy,” consider placing the needle with the aid of a surgical clamp. b. Recognize the increased risk of exposure to the physician when obtaining lateral views under fluoroscopy,6 especially when injecting dye under lateral fluoroscopy, as the beam is often very close to the physician. This is an issue with lumbar discography, as injections of dye are often performed in the lateral view to visualize dye spread into the nucleus. It is prudent to inject from the side of the image intensifier or to have the technician operate the beam during that time so that the physician may stand at a distance from the beam. Limit the use of magnification. The magnification function permits a magnified view of the image to appear on the screen, which may enhance the ability to accurately view the needle position. However, this comes at the expense of increased radiation exposure. If magnification must be used, limit its use to the lowest magnification setting possible. Placing the patient closer to the beam will magnify the image but at the expense of increased radiation exposure. One method for obtaining a magnified view is to use the “zoom” feature on the machine. This is a feature of the machine that when selected magnifies or “zooms in” to the center of the last image held. It simply magnifies the picture seen on the screen, but it does so without additional radiation exposure. Limit the use of high-level fluoroscopy (HLF) imaging. This function of the fluoroscopy machine increases the current (mA) in order to improve the image quality.8 This function is activated when the “+” sign is pressed on the x-ray switch or foot pedal. Use this function sparingly in order to limit excessive radiation exposure. Avoid continuous fluoroscopy using HLF imaging. HLF is most often used to obtain an image that may then be saved for documentation of the final needle position. Limit personnel in the procedure room to those directly involved with that patient’s care. Most C-arms will automatically adjust to a high voltage (kV) while keeping the current (mA) low. If the setting is placed at “low dose,” then the current decreases by approximately two thirds. This results in a higher voltage per current going through the patient, which is more desirable for both the patient and the pain physician (see Figure 3.5, Figure 3.6A, and Figure 3.6B). With each exposure, there will often be a number expressed in terms of radcm2. This is a calculated measure of radiation emitted by the machine with respect to the patient’s body surface area, known as the dose area product (DAP). While this value has limitations in its interpretation, it is useful as a relative value to try to minimze the DAP exposure for each patient. Obese patients present a challenge, both in needle placement and visualization of the anatomy under fluoroscopy. The use of low-dose settings in these patients results in a reduction in the image clarity; thus, a higher current (mA) is often required to obtain a discernable image. Also, magnification is more often used for these patients in order to get a clearer image. Lastly, the equipment should be well maintained and regularly serviced to ensure good working order (Figure 3.5).

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PULSE

FILM

LOW DOSE

GENERATOR

FIGURE 3.5 Areas on the control panel of the C-arm where pulse and low dose imaging settings may be applied.


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A needle placed in the foramen

(A)

A needle placed in the foramen

(B)

FIGURE 3.6 (A) This image was collimated both longitudinally (vertically) and circumferentially. The image was taken under pulsed fluoroscopy on the “low dose” setting. There is some decrease in resolution, but the needle is still well visualized. (B) The same image without pulsed fluoroscopy. Note the improved resolution.

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39

Shielding The use of shields may help to decrease exposure to the physician and staff due to scatter from the patient. Below are the most common types of shields in use: 1. Lead aprons decrease exposure to the physicians’ organs by >90%. These aprons should contain a thickness of at least 0.25 mm lead — >0.5 mm thickness provides more protection.6 They should be routinely checked to ensure that they continue to act as effective barriers, and they should not be folded. 2. Thyroid shields protect the thyroid gland from radiation, which may cause thyroid cancer. 3. Protective lead eyewear decreases exposure to the eyes by 90%. Although high doses are required to produce radiation-induced cataracts, the risk also increases with age and the number of years of radiation exposure. The protective eyewear should also be equipped with lateral shields to protect scatter coming from the side. 4. Leaded gloves may be of use. There are some who are opposed to leaded gloves due to the false sense of security that they may confer. The use of leaded gloves, while helpful in reducing scatter to the hands, is not a sustitute for adhering to the above radiation safety principles. If the physician’s hand is left under the beam and he or she is wearing leaded gloves, the fluoroscopy machine, which has automatic brightness control, increases the radiation output in order to get a better image of the practitioner’s hand, thus negating the benefit of the leaded gloves. There is also often a trade-off, as the leaded gloves may decrease the manual dexterity of the physician. 5. Protective mobile barriers are leaded panels that may be placed between the practitioner and the patient.

Radiation exposure is cumulative. Radiation badges should be worn with each exposure and returned for monitoring at monthly or bimonthly intervals. There are different types of monitoring equipment: 1. External exposure: This badge is often worn around the collar. 2. Organ exposure: This badge is worn underneath the lead. 3. Extremity/hand exposure: This is a finger ring — the label should be on the side that is exposed to radiation.

In conclusion, fluoroscopy is a tool that the pain practitioner uses to guide him or her in accurately placing medications around the spinal column, decreasing the volume of injectate necessary to achieve a positive result. Basic knowledge of the risks and possible complications of fluoroscopy is a vital part of performing these procedures.

Bibliography 1. Manchikanti, L., Cash, K., Moss, T.L., and Pampati V., Radiation exposure to the physician in interventional pain management, Pain Physician, 5(4), 385–393, 2002. 2. Manchikanti, L., Cash, K.A., Moss, T.L., Rivera, J., and Pampati, V., Risk of whole body radiation exposure and protective measures in fluoroscopically guided interventional techniques: a prospective evaluation, BMC Anesthesiology, 3, 2, 2003. 3. Brateman, L., The AAPM/RSNA Physics Tutorial for Residents, Imaging & Therapeutic Technology, 19(4). 4. FDA Public Health Advisory, Avoidance of Serious X-Ray Induced Skin Injuries to Patients during Fluoroscopically Guided Procedures, Food and Drug Administration, Rockville, MD, September 9, 1994. 5. Hernandez, R.J. and Goodsitt, M.M., Reduction of radiation dose in pediatric patients using pulsed fluoroscopy, American Journal of Roentgenology, 167, 1247–1253, 1996. 6. Fishman, S.M. et al., Radiation safety in pain medicine, Regional Anesthesia and Pain Medicine, 27(3), 296–305, 2002.

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7. Mahesh, M., Fluoroscopy: patient radiation exposure issues. Radiographic, 21(4), 1033, 2001. 8. OEC Workstation Operator Manual 1998–2001. 9. Archer, B.R. and Wagner, L.K. Protecting patients by training physicians in fluoroscopic radiation management. Am. Coll. Med. Phys., 1(1), 32–37, 2000.

Chapter

Basic Steps for Spinal Injections

4

41



43

Prior to any spinal injection, there is some basic preparation that needs to take place. All of the necessary supplies and equipment for planned procedures should be available before the case is started. General recommendations will be given for equipment and supplies, and specifics will not be outlined, as different institutions have varying preferences. There are six basic steps for every spinal injection. We will describe all procedures by following these steps: Step 1: Identify the target area or location of the spine that is to be injected, and determine the desired needle pathway. Step 2: Position the patient appropriately for the injection. Step 3: Use fluoroscopy to identify the target area along the patient’s spine. Step 4: Insert the needle into the target point or area of the spine using fluoroscopy as a guide. Step 5: Confirm the needle placement under fluoroscopy. Step 6: Inject the desired medication in the target area.

Step 1: Identify the Target Area or Location of the Spine to Be Injected (Figure 4.1) We often have a spine model in our procedure room for reference. In order to determine the needle path (Figure 4.2), we must determine how to insert the needle from the site to reach the target area or point of the spine.

FIGURE 4.1 Identify the target area or location of the spine.

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FIGURE 4.2 Determine how to insert the needle from the site to reach the target area or point of the spine.

Step 2: Position the Patient for the Injection Figure 4.3 demonstrates that a patient is placed in the prone position.

FIGURE 4.3 Denotes that a patient is placed in the prone position.


45

Step 3: Use Fluoroscopy to Identify the Target Area Along the Patient’s Spine This step includes placing the target area of the spine in the center of the TV screen (Figure 4.4 through Figure 4.9), orienting the images of the spine (Figure 4.10), confirming the target level of the spine image (Figure 4.11), and rotating the C-arm to get the desired spinal images for the initial needle insertion (Figure 4.12).

111111 1111 111

111111 111111

FIGURE 4.4 The fluoroscopic photo is displayed in the center of this TV screen.

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111111 1111 111

111111 111111

FIGURE 4.5 The object is displayed on the left side of TV screen. The C-arm should be moved toward the spine.


47

111111 1111 111

111111 111111

FIGURE 4.6 The object is displayed on the right side of TV screen. The C-arm should be moved away from the spine.


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1111 1 1

C-arm

1111 111

111111 111111

FIGURE 4.7 The axis of the C-arm should be perpendicular to the axis of a patient’s spine in order to display a perpendicular image on the screen.

11111 1

1111 1 1

1111 111

1111 111

111111 111111

111111 111111

FIGURE 4.8 Images are rotated on screen when the C-arm’s axis is not perpendicular to the axis of patient’s spine.


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Spine film

Spine film

Displaying on TV screen

Patient’s left side

Left

Right

FIGURE 4.9 The C-arm displays an image of the lumbar spine of the prone patient on the TV screen.

T12

L5

Rib Ri

Left

Sacrum

Left

FIGURE 4.10 An image of the sacrum and an image of T12 help confirm levels of the vertebral image.

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L4 FIGURE 4.11 Rotating the C-arm to the patient’s right side to get a right-sided oblique view of the image of the lumbar spine.


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Step 4: Insert and Advance the Needle to the Target Point or Area of the Spine under C-arm Fluoroscopy (Figure 4.12)

A needle

FIGURE 4.12 Demonstration of inserting a needle.


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Step 5: Confirm the Needle Placement In this case (Figure 4.13 through Figure 4.16), we demonstrate a right-sided lumbar transforaminal epidural steroid injection. Contrast solution is injected to outline the target area in the spine to reconfirm the relationship between the needle tip and the target area — the contrast material outlines an epidural space and a spinal nerve root (Figure 4.16 and Figure 4.17).

The initial needle placement FIGURE 4.13

A needle FIGURE 4.14 The depth of the needle placement on a lateral view.


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A needle

FIGURE 4.15 The relationship between the needle tip and the target area of the lumbar spine is rechecked on an anterior–posterior (A/P) view.

Needle

FIGURE 4.16 Lateral view of the lumbar spine.

Contrast material spreads into the epidural space

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Needle

Contrast material spreads into the epidural space and outlines a spinal nerve root

FIGURE 4.17 A/P view of the lumbar spine.

Step 6: Inject the Medication (e.g., local anesthetic and steroid) As the doses of local anesthetic and steroid vary with the individual, we will not be specific in our recommendations.

Bibliography Bontrager, K.L. and Anthony, B.T., Eds., Textbook of Radiographic Positioning and Related Anatomy, 2nd ed., C.V. Mosby Company, St. Louis, MO, 1990. Brown, D.L., Ed., Atlas of Regional Anesthesia, 2nd ed., W.B. Saunders, Philadelphia, 1999. Finton, D.S. and Czervionke, L.F., Eds., Image-Guided Spine Intervention, W.B. Saunders, Philadelphia, 2003. Waldman, S.D., Ed., Atlas of Interventional Pain Management, 2nd ed., W.B. Saunders, Philadelphia, 2004.

Chapter

Fluoroscopic Images of the Lumbar Spine

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57

Positioning the Patient The prone position is the most frequently utilized position for all lumbar spinal injections (Figure 5.1). A typical fluoroscopic image of the anterior/posterior (A/P) view of the lumbar spine is shown in Figure 5.2.

FIGURE 5.1 Prone position commonly used for lumbar spinal injections.

Anterior/Posterior View of the Lumbar Spine

4 1 6

5

2

3

FIGURE 5.2 Left: A/P view of the lumbar vertebrae. (1) Pedicle, (2) lamina, (3) spinous process, (4) superior articular process, (5) inferior articular process, and (6) transverse process. Right: Photograph of the posterior aspect of a lumbar vertebra.

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Figure 5.3 shows two images of A/P view of patients’ lumbar spines. Often, these images are difficult to interpret.

FIGURE 5.3 A/P views of lumbar spines.


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Obtaining an Oblique View of the Lumbar Spine Figure 5.4 shows a typical fluoroscopic image of the right oblique view of the lumbar spine. The C-arm is rotated to the patient’s right side. The image of the “Scottie dog” helps us to identify the structures of the lumbar vertebrae. The “neck” of the dog represents the connection between the pedicle and the lamina. The “ear” is the superior articular process. The “eye” is formed by the pedicle. And, the ipsilateral transverse process forms the “nose” of the dog.

4

6

1 2

3 5

4 6 1 2 3

5

The “Scottie Dog” image FIGURE 5.4 Image of the right oblique view of the lumbar spine. (1) Pedicle (the eye of the dog), (2) lamina, (3) spinous process, (4) superior articular process (the ear of the dog), (5) inferior articular process (the front leg of the dog), and (6) transverse process (the nose of the dog).

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Figure 5.5 demonstrates how an image of the lumbar spine is changed from an A/P view to an oblique view. The more the C-arm is rotated to the patient’s right, the greater is the distance between the right-sided lateral margin of the vertebral body and the tip of the spinous process. Margin of the vertebral body

Tip of the spinous process

FIGURE 5.5 Change of view of lumbar spine from A/P to oblique.


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Figure 5.6 shows several images of the oblique view of the lumbar spine. The key difference in these images is the relationship between the axis of the superior articular process and the axis of the pedicle shadow. We can get different images of the oblique view (the “Scottie dog” images) of the lumbar spine by rotating the C-arm to the patient’s side with slightly different angles based on the procedures. For example, we may choose Image A for the lumbar medial branch injections. (See the section on lumbar facet injections in Chapter 6 for details.) We may choose Image F for the lumbar discography. (See the section on lumbar discography in Chapter 6 for details.)

FIGURE 5.6 Different images of oblique views of the lumbar spine.


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Obtaining an Lateral View of the Lumbar Spine Figure 5.7 is a typical fluoroscopic image of the lateral view of the lumbar spine. We usually use a lateral view image to confirm needle depth. Figure 5.8 demonstrates that it may be very difficult to determine which image is a true lateral view of the lumbar spine. We obtained these three images by slightly rotating the C-arm without changing needle position (neither advancing the needle nor retracting the needle).

1

4

5

7

2 3

6

FIGURE 5.7 (1) Pedicle, (2) spinous process, (3) superior articular process, (4) inferior articular process, (5) transverse process, (6) vertebral body, and (7) intervertebral foramen.


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FIGURE 5.8 Three-images of lumbar spine (lateral view).

Figure 5.9 illustrates a lateral view of the lumbar spine in a prone position. The shape of the vertebral body is like a cylinder; the transverse processes on the sides, the lamina, and the spinous process form a pie. Two small cylinders (two pedicles) connect “the cylinder” and “the pie.”

Tip of the spinous process Tip of the transverse process Pedicles

Tip of transverse process Vertebral body

FIGURE 5.9 Lateral view of lumbar spine in prone position.


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We can easily view a clear lateral vertebral body (the cylinder) with pedicles by having the x-ray beam pass through a diameter of the cylinder (Figure 5.10A). However, it may be difficult to determine a true lateral view of the vertebral body, because the cylinder has many diameters (Figure 5.10B). Therefore, it is not easy to determine needle depth by using images of the lateral view only (Figure 5.11).

A

FIGURE 5.10

B


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Figure 5.11 illustrates different images of the lateral view of the lumbar spine without moving needles. Rotating the C-arm at slightly different angles can change the distances between the tip of the needle and the anterior margin of the vertebral body.

A

B

FIGURE 5.11 Lateral views of the lumbar spine.


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Other structures in the lateral view of the lumbar spine, including the transverse process, the superior articular process, the interior process, and the spinous process, do not provide additional information for determining a true lateral view of the lumbar spine (Figure 5.12A). A twodimensional image of the lumbar spine can be illustrated as in Figure 5.12B. We are able to easily identify the vertebral body, the pedicle, and the intervertebral foramen. Vertebral body

Vertebral body

Intervertebral foramen Intervertebral foramen

Pedicle

Pedicle A FIGURE 5.12

B


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Suggestions on How to Check the Needle Depth When imaging the lumbar spine, it is difficult to check the needle depth by realigning the images of the lateral view alone (Figure 5.11). In contrast, it is easy to get a true A/P view of the lumbar spine if an x-ray beam goes through the diameter of “the cylinder” and is perpendicular to “the pie” (Figure 5.13). Therefore, we recommend using images of both the lateral view and the A/P view of the lumbar spine together to confirm needle depth (Figure 5.14). The perpendicular Tip of the spinous process

Tip of the transverse Pedicles

Tip of transverse process Vertebral body

The diameter

A

B

FIGURE 5.13 Fluoroscopic images of A/P views of the lumbar spine. The spinous process (A) is located at the midline of the vertebral body, and the vertebral body (B) is squared (commonly used terminology).

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FIGURE 5.14 Images of the lateral view and the A/P view should also be used to check the needle depth. (A) Lateral view. The tip of this needle is located slightly posterior to the anterior margin of the vertebral body. (B) A/P view. The tip of the needle is located in the center of the pedicle shadow.


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Bibliography Bontrager, K.L. and Anthony, B.T., Eds., Textbook of Radiographic Positioning and Related Anatomy, 2nd ed., C.V. Mosby Company, St. Louis, MO, 1990. Brown, D.L., Ed., Atlas of Regional Anesthesia, 2nd ed., W.B. Saunders, Philadelphia, 1999. Clemente, G.D., Ed., Gray’s Anatomy, 13th ed., Lea & Febiger, Philadelphia, 1984. Fenton, D.S. and Czervionke, L.F., Eds., Image-Guided Spine Intervention, W.B. Saunders, Philadelphia, 2003. Netter, F.H., Ed., Atlas of Human Anatomy, Ciba Geigy Corporation, Tarrytown, 1989. Waldman, S.D., Atlas of Interventional Pain Management, 2nd ed., W.B. Saunders, Philadelphia, 2004.


Chapter

Lumbar Spinal Injections

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Lumbar Spinal Injections This chapter addresses injections in and around the lumbar spine. We start off with the simplest to perform, the lumbar medial branch block, and advance to the more technically challenging lumbar discogram. The pain physician should be skilled in the performance of lumbar spinal injections prior to attempting to perform injections within the thoracic or cervical regions. Patient preparation: We ask the patients not to ingest any solid foods for a minimum of 6 hours prior to the procedure. We recommend that the patients have another individual available to transport them home following the procedure. Heart rate, blood pressure, and oxygen saturation may be monitored. Pregnancy is a contraindication to the performance of all spinal injections under fluoroscopy. Equipment/Materials: • • •

• • • •

A 22- or 25-gauge 3½ in. spinal needle with or without a distal curved tip in the direction of the bevel. Water-soluble nonionic contrast. Local anesthetic (e.g., 0.25 to 0.5% bupivacaine or 2% lidocaine) and steroid. The volume of injected material will vary depending on the injection performed. Diagnostic injections are performed with a low volume (70%) pain relief from diagnostic lumbar medial branch injections, he or she is a good candidate for the lumbar medial branch denervation. We follow the same step to get a slightly obliquely viewed image of the target vertebra (Figure 6.20). We usually choose the initial radiofrequency needle entry point at the lower margin of the transverse process and slightly lateral to the lateral margin of the pedicle shadow (Figure 6.21A). The needle is then advanced slightly medially and cephalically. The end point of the process is when the needle tip contacts the junction point between the superior articular process and the transverse process, as we described in the above section on the lumbar medial branch block (Figure 6.21B).


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A

B

FIGURE 6.20 (A) Right-sided oblique view of the lumbar vertebra above L5. (B) Right-sided oblique view of the L5 vertebra.

The initial needle entry point (A)

(B)

FIGURE 6.21 (A) Initial entry point and (B) target area.

Needle placement should be rechecked at the lateral view, as described in the lumbar medial branch block section, above.

Lumbar Transforaminal Epidural Steroid Injection Step 1: Identify the Target Area Needle entry is via an intervertebral foramen posteriolaterally (Figure 6.22A and Figure 6.22B).


A

89

B

FIGURE 6.22 (A) Photograph of a posterior view of the lumbar spine with a needle approaching the foramen. (B) Photograph of the lumbar spine with a needle approaching in the oblique view.

Step 2: Position the Patient The patient is in a prone position, and the C-arm comes in from the patient’s side (Figure 6.23).

FIGURE 6.23 C-arm at side of patient in prone position.


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Step 3: Use Fluoroscopy to Identify the Target Area The C-arm is rotated and tilted to get an A/P image of the target lumbar vertebra (Figure 6.24A through Figure 6.24C). The C-arm is then rotated toward the affected side to get an oblique fluoroscopic image of the target lumbar vertebra (Figure 6.25A and Figure 6.25B). T12 L5 Left

Right Rib

A shadow of a metal pointer

Sacrum

A

B

A shadow of a metal pointer

C

FIGURE 6.24 (A, B) Orientation of the image; the levels may be counted from T12 to ensure that there are five lumbar vertebrae. (C) A/P view of the first to third lumbar vertebrae. Their spinous processes are at the midline of the vertebral bodies, but only the L1 and L2 vertebral bodies are squared.


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A

B

FIGURE 6.25 (A) Photograph of the lumbar spine, right oblique view. (B) Fluoroscopic image of the lumbar spine, right oblique view.

In general, the best oblique view of the lumbar spine for a lumbar transforaminal epidural steroid injection is obtained when the superior articular process at the target level intersects the center of pedicle shadow that is located immediately above (Figure 6.26).

Tip of superior articular process points up to the center of the pedicle above. Target vertebra

FIGURE 6.26 Correct right oblique view of lumbar vertebrae for lumbar transforaminal epidural steroid injection.

Step 4: Insert the Needle to the Target Area When performing a lumbar transforaminal injection, the entry (Figure 6.27A) is located as follows: At the inferior margin of the transverse process at the target vertebra Superior to the tip of the superior articular process at the level below the target vertebra Lateral to the lateral margin of the inferior articular process at the level below the target vertebra

Figure 6.27B shows the initial needle placement.


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Target vertebra

Inferior margin of transverse process Lateral margin of inferior articular process Tip of superior articular process

A

Needle

B

FIGURE 6.27 (A) Zone of initial needle placement. (B) Fluoroscopic image of the initial needle placement for right-sided lumbar transforaminal epidural steroid injection.

Step 5: Confirm the Needle Placement The depth of the needle should be checked with lateral views. The final depth of the needle in the lateral view is located between the middle and the posterior one third of the intervertebral foramen (Figure 6.28A). In the A/P view, the needle tip should be located underneath the pedicle shadow, with the area between the medial margin and the center of the pedicle shadow at the target level (Figure 6.28B). If the patient experiences severe paresthesias, regardless of the needle position, the needle must be repositioned.


93

B

A The needle tip is located at the midway and upper one third of intervertebral foramen

The needle tip is located underneath of the pedicle and between the medial margin and center of the pedicle

FIGURE 6.28

A lateral image and an A/P fluoroscopic image of epidurogram, which may include a nervegram, should be obtained. Vertical epidural spread of the contrast agent is visualized within the posterior aspect of the intervertebral foramen in the lateral view (Figure 6.29A). In the A/P view, the contrast agent spreads underneath and medial to the pedicle shadow and outlines the target spinal nerve exiting the foramen (Figure 6.29B).

(A) FIGURE 6.29

(B)


94

Step 6: Inject the Medication We recommend injecting 1 to 2 ml of 0.25% of bupivacaine and 10 to 40 mg (0.2 to 1 ml) of steroid.

Special Considerations of Oblique Views It is important not to under- or overrotate the C-arm in obtaining an ideal fluoroscopic image (Figure 6.30). Learning how to get the correct oblique image of the lumbar spine is important for performing lumbar transforaminal epidural steroid injections. The following figures demonstrate oblique images of the lumbar vertebra that can interfere with accurate needle placement (Figure 6.30A through Figure 6.30C).

A

B

C

FIGURE 6.30 (A) C-arm in a neutral position. (B, C) The C-arm when it is rotated to the patient’s right side at varying angles.


95

Rules for Getting Oblique Views of the Lumbar Spine Figure 6.31 demonstrates that the needle cannot be inserted into the intervertebral foramen if it is inserted perpendicularly to the vertebral body, posterior–anterior from above the tip of the superior articular process. For this reason, we do not use the A/P view of the lumbar spine to guide the initial needle insertion.

A B

C

Vertebral body Transverse process

Needle

Spinal nerve root

Pedicle Spinal cord

Tip of superior articular

Spinous process lamina

FIGURE 6.31 (A) Photograph of the lumbar spine with a needle in the posterior view (B) A/P fluoroscopic image of the lumbar spine. (C) Diagram showing the difficulty encountered when the needle is inserted from the skin perpendicularly to the vertebral body from above the tip of the superior articular process.


96

Figure 6.32 shows the difficulty in accurately placing the needle into the intervertebral foramen when there is underrotation of the image of the lumbar vertebra by C-arm.

Tip of superior articular process points up to the lateral margin of the pedicle at the level above

A

B

C

FIGURE 6.32 (A) Photograph of under-rotated lumbar vertebrae with a needle entry from right oblique view. (B) Fluoroscopic image of the lumbar spine showing the right oblique view, under-rotated. The tip of the superior articular process points up to the lateral margin of the pedicle shadow above. (C) Example of how an under-rotated vertebra makes the needle placement more difficult.


97

Proper rotation of the C-arm with respect to the lumbar vertebrae allows the needle tip to pass easily into the intervertebral foramen (Figure 6.33).

Tip of superior articular process points up to the center of the pedicle at the level above

A

B

C

Needle

FIGURE 6.33 (A) Photo of properly rotated vertebrae to the right. (B) Fluoroscopic image of the lumbar spine, right proper oblique view. The tip of the superior articular process points up to the center of the pedicle shadow at the level above. (C) Proper rotation of the lumbar vertebra and the proper needle placement. The needle is able to be inserted into the intervertebral foramen.


98

Figure 6.34 demonstrates that overrotation of the C-arm also increases the difficulty of performing accurate needle placement.

The tip of superior articular process is located at the center of the disc space

A

B

C

Needle FIGURE 6.34 (A) Lumbar vertebrae over-rotated to the right. (B) Fluoroscopic image of lumbar vertebrae over-rotated to the right because the tip of the superior articular process is at the midway of the disc space between two vertebrae. (C) Improper needle placement.


99

The following images (Figure 6.35) illustrate a left transforaminal epidural steroid injection at the level of L4/L5. We changed C-arm rotations to correct the initial inaccurate needle positions. C

B

A

D

E

Tip of superior articular process points up to the lateral margin of pedicle at level above

Tip of superior articular process points up to the center of pedicle at the level above

F

G

H

I

FIGURE 6.35 (A) Initial needle insertion in the left oblique view. (B) A false “proper needle location” at the lateral view (needle tip at the upper one third and at the midway of the intervertebral foramen). (C) Needle tip away from the spine in the A/P view. (D) A second oblique view obtained by rotating the C-arm to the left. The initial needle entry in (A) was medial to the superior articular process. (E–H) In order to obtain the proper needle placement it was necessary to check the oblique, lateral, and A/P views. (I) A correct segmental epidurogram with a nervegram.


100

The images shown in Figure 6.36A through Figure 6.36H demonstrate how overrotating the C-arm also results in improper needle placement. Figure 6.36A shows the superior articular process of L2 pointing up to the medial margin of the pedicle shadow at the level above. Figure 6.36B through Figure 6.36D show the needle placement when this overrotated oblique view is used. Figure 6.36E and Figure 6.36F show “proper” needle placement in the A/P view and in the lateral view. However, Figure 6.36F shows improper spread of contrast agent. Figure 6.36H confirmed that it is not an epidurogram.

A

B

C

D

E F

H

G

Improper spread of contrast agent

This contrast image is not an epidurogram

FIGURE 6.36 Improper spread of contrast agent.


101

Sometimes getting an ideal oblique image of the lumbar vertebrae for lumbar epidural steroid injections is difficult, because the shapes of patients’ lumbar vertebrae vary. This means that we cannot always use the relationship between the tip of the superior articular process and the pedicle shadow at the level above on the oblique view (Figure 6.37A through Figure 6.37D) to decide a proper C-arm oblique rotation.

Target vertebra

Tip of superior articular process points up to the center of the pedicule above

FIGURE 6.37

In Figure 6.38A through Figure 6.38D, the relationship between the tip of a superior articular process could not be used as a guide for the lumbar transforaminal epidural steroid injection. Figure 6.38A looks like an overrotated oblique view lumbar spine image, because the tips of the superior articular processes at each level from L2 to L4 point up to the medial margin of the pedicle shadow above. In Figure 6.38B, the needle is inserted between L1 and L2. Figure 6.38C shows an A/P view of proper needle placement, as the needle tip is located below the pedicle shadow and also medial to the medial margin of the pedicle shadow. Figure 6.38D shows a correct epidurogram and nervegram.


102

A

Needle

C

FIGURE 6.38

B

Needle

D


103

We believe that the angle between the transverse process and the superior process (Figure 6.39) is one of the factors that accounts for varying appearances of the lumbar vertebrae in the oblique view. Angle between transverse process and superior articular process

FIGURE 6.39 The arrow shows the angle between the transverse process and the superior articular process.

We can use the relationship between the tip of the superior articular process and the upper margin of the vertebral body as a guide to confirm the correct oblique view if the angle is close to 90° (Figure 6.40). This does not hold true if this angle is much bigger than 90˚ (Figure 6.41). An almost 90° angle

FIGURE 6.40 The angle in this example is sharp.


104

Angle much bigger than 90 degrees

FIGURE 6.41 The angle pictured here is greater than 90°.

This angle is less than 90 degrees.

FIGURE 6.42 We have not observed an angle between the transverse process and the superior articular process that is less than 90°.


105

Therefore, we recommend using at least two rules together to check for optimal oblique images for lumbar epidural steroid injections: Rule 1: The tip of the superior articular process bisects the center of the pedicle shadow at the level above (Figure 6.43 A). Rule 2: The tip of the superior articular process is located at one third of the disc space (Figure 6.43B).

Tip of superior articular process bisects the pedicle shadow above

(a)

1/3 1/3

1/3

(b) FIGURE 6.43

106


We consider Rule 2 to be more important than Rule 1 to determine a proper C-arm position for obtaining a correct oblique image of lumbar spine. We also recommend always using both lateral and A/P images to guide and check needle depth and direction. Figure 6.44A, an oblique view, shows that a needle is inserted below the transverse process (below the pedicle in the fluoroscopic image), lateral to the inferior articular process, and above the superior articular process. Image B, a lateral view, shows that the needle tip is located in the upper one third of the intervertebral foramen. Image C, an A/P view, shows that the needle tip is underneath the pedicle. Figure 6.44 illustrates proper needle placement in oblique, lateral, and A/P views. If we use only a lateral image to check the needle depth, we may not be able to identify improper needle placement. Figure 6.45 demonstrates that three needle placements can give similar lateral photographs.


107

A

B

C

FIGURE 6.44 Proper needle placements in oblique view (A), lateral view (B), and A/P view (C).

108


FIGURE 6.45 The above pictures show that three different needle entrance sites in the A/P views can result in the same needle position in the lateral view.


109

Figure 6.46 illustrates that needles are inserted in different directions to the lumbar spine, proven by A/P views (images A and B). However, lateral images (images C and D) show that these two needle depths are similar.

A

B

C

D

FIGURE 6.46 A/P views of needles inserted from different directions (A and B). Lateral images showing similar needle depths (C and D).


110

The following two cases show how to confirm needle placements: Case 1 (Figure 6.47): Correct needle placement at a level between L4 and L5 on the right side.

Use Rule #1 and #2 to choose an oblique for the initial needle

Use lateral view and A/P view to confirm the needle depth and needle driving direction

Lateral epidurogram FIGURE 6.47 Proper needle placement between L4 and L5 on right side.

A/P epidurogram


111

Case 2 (Figure 6.48): Another correct needle placement at a level between L4 and L5 on the right side.

Use Rule # 1 and #2 to choose an oblique for the initial needle

Use lateral view and A/P view to confirm the needle depth and needle driving direction

Lateral epidurogram

A/P epidurogram

FIGURE 6.48 Another proper needle placement between L4 and L5 on right side.

Lumbar Transforaminal Epidural Steroid Injection at the Level of L5/S1 Step 1: Identify the Target Area The needle is inserted into the intervertebral foramen between L5 and the first sacral segment (ala or wing of the sacrum) (Figure 6.49).

112


Ala or sacral wing FIGURE 6.49 Insertion of needle into intervertebral foramen between L5 and first sacral segment.

Step 2: Position the Patient The patient is in the prone position, as they would be for any other lumbar procedure (Figure 6.50).

FIGURE 6.50 Patient in prone position.


113

Step 3: Use C-Arm to Identify the Target Area Obtaining appropriate fluoroscopic images for L5/S1 transforaminal epidural steroid injections is different than obtaining those for the upper lumbar levels, although the same principles and rules described above apply. There are several special considerations at this level. These include the lumbar lordosis (Figure 6.51A and Figure 6.51B), the sacral promontory (Figure 6.51C), and the concave shape of the sacrum (Figure 6.51B). The vertebral column forms a series of anteroposterior curves. A lordosis is defined as any convex forward curve. The curvature of an adult’s lumbar spine (Figure 6.51) is a convex forward curve.

A Lumbar lordosis (convex forward curve) Sacral curvature (concave forward)

B

C Lumbar lordosis

FIGURE 6.51 Curvature of adult lumbar spine.

Sacral promontory

114


In order to square the L5 vertebral body or to open the disc space between L5 and S1 in the A/P view, the C-arm needs to have a significant cephalic tilt (Figure 6.52). This tilt varies among patients based on their degrees of lumbar lordosis, the severity of the sacral promontory, and the degrees of sacral curvature (Figure 6.53).

FIGURE 6.52


FIGURE 6.53

115


116

If the fluoroscopic beam does not align with the disc between L5 and S1 (Figure 6.54A), the tip of the spinous process of L5 will be located above or on the posterior lower margin of the L5 vertebral body (Figure 6.55B and Figure 6.55C). When the C-arm is tilted in a cephalic direction, it allows the fluoroscopic beam to align with the L5/S1 disc (Figure 6.55A). The tip of the spinous process of L5 will be located below the posterior inferior margin of the L5 vertebral body (Figure 6.55B and Figure 6.55C). The C-arm is then rotated to the affected side (Figure 6.56) to get an obliqueviewed L5 (Figure 6.57A). We still follow Rule 1 as we described above to have the tip of the S1 superior articular process bisecting the pedicle shadow of L5 (Figure 6.57B).

A

X-tube

Lower margin of L5 lamina

Tip of spinous process is located above the posterior lower margin of L5 vertebral body

B

c Posterior margin of sacrum body

Posterior lower margin of L5 vertebral body FIGURE 6.54 In (B) and (C) the fluoroscopic beam is not aligned with the disc between L5 and S1. (B) Posterior view of L5 and the disc space between L5 and S1 when the fluoroscopic beam is not aligned with the disc. (C) A/P image of an L5 body whose image is not squared.


117

A The tip of the spinous process is located below the posterior inferior margin of the L5 vertebral body. X tube

B

The posterior lower margin of the L5 vertebral body

C

FIGURE 6.55 The fluoroscopic beam is aligned with the L5/S1 disc. (B) The appearance of the L5 vertebral body and the disc space between L5 and S1 when the fluoroscopic beam aligns with the disc. (C) A/P viewed image of a squared L5 body.

FIGURE 6.56


118

Tip of S1 superior articular process bisects L5

A

B

FIGURE 6.57 (A) Photograph of L5, left oblique view. (B) Fluoroscopic image of L5, left oblique view; the tip of the left superior articular process bisects the pedicle shadow at L5.

A triangular-shaped needle entry zone is formed by the iliac crest (lateral), the lateral margin of the S1 superior articular process (medial), and the inferior margin of the transverse process (superior) (Figure 6.58). The needle should be inserted above the tip of the S1 superior articular process (Figure 6.59). L5 transverse process

S1 superior articular process

Iliac crest FIGURE 6.58


Needle insertion point

FIGURE 6.59

119


120

However, we observed that the needle entry zone as described above varies among patients due to the differences in the appearance of the iliac crest (Figure 6.60). These differences sometimes make needle insertion very difficult, because a high iliac crest line may cover the needle entry zone in the oblique view (Figure 6.61).

L5

L5 B

A

L5

CC

FIGURE 6.60 Different appearances of the iliac crest. A is higher than B. C is lower than A and B.


121

L5

L5 Iliac crest line A Iliac crest

L5

L5 Iliac crest line Iliac crest

B

L5 L5

Iliac crest line C Iliac crest FIGURE 6.61 Different appearances of the iliac crest in a left oblique view.

We recommend always trying to rotate the C-arm to the affected side until the superior articular process of S1 bisects the L4 pedicle shadow in order to get an initial needle entry point if the iliac crest line is low in this view (Figure 6.62).


122

Needle FIGURE 6.62 Initial needle placement for left-side L5/S1 transforaminal epidural steroid injection.

Step 4: Insert the Needle to the Target Area However, if the iliac crest covers the needle entry zone in an oblique view, we recommend rotating the C-arm until this needle entry zone is maximally open. The needle entry will then be chosen at a position lateral to the tip of the S1 superior articular process (Figure 6.63). The needle is then advanced in this oblique view until it contacts either the upper portion of the lateral margin of the S1 superior articular process or the inferior portion of the lateral margin of the L5 inferior articular process (Figure 6.64).

Initial needle entry point

A

L Iliac crest line

B

FIGURE 6.63 (A) Marked needle entry point in an oblique view. (B) Initial needle placement.


A

123

B The needle tip contacts the lateral side of the S1 superior articular process

FIGURE 6.64 (A) The needle contacts the lateral margin of the S1 superior articular process. (B) The needle tip contacts the upper portion of the lateral margin of the S1 superior articular process.

The needle tip behind S1 superior articular process FIGURE 6.65 The needle tip is behind the S1 superior articular process.


124

Step 5: Confirm the Needle Placement The depth of the needle placement should be checked in a lateral view (Figure 6.66A) and an A/P view as described before (Figure 6.66B).

A

B

FIGURE 6.66 Lateral view of needle placement (A). A/P view of needle placement (B).

A

B

FIGURE 6.67 (A) Left-sided L5/S1 epidurogram, including the L5 nervegram and S1 nervegram in an A/P view. (B) L5/S1 epidurogram in a lateral view.

Lumbar Discography Introduction Lumbar discography is a diagnostic test that seeks to provide clinically relevant information about the source of a patient’s low back pain, with or without radiation to the lower extremity, that is not provided by other imaging techniques, such as magnetic resonance imaging (MRI). Radiographically, abnormal lumbar discs may or may not be associated with the patient’s symptoms.2 The outer annulus is richly innervated.3,4 Injection of dye within the substance of the pain-generating disc often reproduces the patient’s pain symptoms. This is particularly significant if the concordant pain is reproduced at low injection


125

A H IZ

FIGURE 6.68 On the posterior aspect of the L23 and L45 disc is a bright spot known as a high intensity zone (HIZ).

pressures.5 The disc is comprised of three main regions: the nucleus pulposus, the annulus fibrosus, and the cartilaginous end plates. Mechanical stress is mostly distributed to the lumbar vertebral end plate, which is the disc’s source of nutritional supply. Disc degeneration is thought to be the result of repetitive mechanical stress to the disc, although this is not necessarily associated with direct trauma. Discogenic pain, i.e., pain emanating from within the disc, is often axial low back pain and is frequently aggravated by the assumption of certain body positions (e.g., prolonged sitting and valsalva). Patients with discogenic pain often have annular tears or fissures within the disc that contribute to their pain symptoms. Radiographically, these fissures may appear on the MRI as a “high-intensity zone” (HIZ) (Figure 6.68) on the T2 weighted image. This HIZ on the MRI represents a “radial” or “type II” annular tear. Radial tears are concentric fissures in the annular fibers. In the past, a HIZ was described as a reliable marker of painful disc disruption, but that concept has since been disputed.6–8 The presence of HIZs was noted in asymptomatic as well as symptomatic individuals.6 While MRIs give useful information on disc morphology, they are limited in their clinical application, as HIZs or other disc abnormalities are not always pain generators in an individual patient. The MRI cannot identify which disc is causing the patient’s pain. Performing a provocative discogram that recreates the patient’s exact (concordant) pain symptoms seeks to establish the pain-generating lumbar disc. Prior to performing discography, other sources of pain and spinal pathology should be ruled out with radiographic studies. Once these have been ruled out and a discogram is performed at least two discs must be evaluated. In order to have a valid provocative discogram, it is important to establish that there is a nonpainful (control) disc.9 A painful discogram at a single level without a nonpainful control discogram is a meaningless diagnostic test. Thus dicograms need to be performed at both the suspected pain generating disc and at a control disc. While there may be back discomfort as a result of intradiscal injection of contrast into a normal disc, an injection into a normal disc usually does not produce concordant pain symptoms. There are two types of information that may be obtained from lumbar discography: 1. The presence or absence of concordant pain in response to the injection of contrast (provocative discography) 2. Information regarding the disc morphology based on the way in which the contrast spreads.


126

Provocative discography is the only means that we have to distinguish painful or symptomatic discs from those that are not sources of pain. There is a risk of false-positive results, and thus, patient selection is very important.10 Disc morphology can be further evaluated with a postdiscography computed tomography (CT), where contrast can be seen within the annular tears. The CT should ideally be performed within a few hours of the discogram to ensure adequate visualization of the contrast. Discography is not for everyone; discography on asymptomatic volunteers and patients with somatization disorder has reported high false-positive rates.10 Patients who report pain during a discogram performed on a nondisrupted disc are more likely to have elevated hypochondriasis, hysteria, and depression scores on the Minnesota Multiphasic Personality Inventory (MMPI).11 Indications: 1. 2. 3. 4.

Failure of all other diagnostic tests to provide the source of back pain Diagnosis of the source of back pain in patients who are surgical candidates or are candidates for intradiscal procedures Evaluation of the level above or below the level of a fusion Determination of symptomatic levels in a patient with multilevel disc disease

Contraindications: 1. 2. 3. 4. 5. 6.

Patient refusal Systemic infection Systemic anticoagulation Pregnancy Severe allergy to nonionic dye Severe spinal stenosis

Complications: 1. 2. 3. 4. 5. 6.

Back pain Discitis Arachnoiditis Damage to the disc Postdural puncture headache Meningitis

Equipment/Materials: 1. 2.

3. 4.

5. 6. 7. 8.

See the equipment and materials section at the beginning of this chapter — those listed below are in addition to those listed at the chapter’s beginning. With the exception of very thin patients, discography requires a longer needle than the 3½ in. spinal needle used for most other spinal injections. A 25-gauge 4 11/16 in. or 5 in. needle may be used in the average-sized patient. A 25-gauge discography needle with an introducer may be used. These are especially helpful in performing L5/S1 discograms. Alternatively, a long (7 in., 22-gauge) spinal needle may also be used for obese patients. Curving the needle at the distal tip in the direction of the needle bevel allows for easy navigation of the needle, particularly when attempting to enter the L5/S1 disc. Strict sterile technique is applied at all times; the needle should be kept within its sheath until the time of use. Avoid handling the needle tip prior to the insertion of the needle. A manometer is helpful when quantifying intradiscal pressures. It is also helpful when creating a chart to document intradiscal pressures. Prophylactic intravenous antibiotics, to be administered within 30 min of the procedure. Water-soluble, nonionic contrast dye. Although there is no literature showing added benefit, we also give patients both intradiscal antibiotics. The intradiscal antibiotics are given in combination with


9.

127

the injected contrast (e.g., 1 to 10 mg/ml cefazolin). Generally, no more than 3 ml of dye is injected into each disc. The patient should be given instructions on post-procedure expectations and possible complications.

Manometry Derby described using pressure-controlled discography to predict outcome. It provides a more quantitative description of the discography results.12 The opening pressure is that pressure at which dye was first observed within the disk space.5 A chemically sensitive disc is one that reproduces concordant pain at low disc pressures (

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