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Copyright © by McGraw-Hill Education. All rights reserved. Except as permitted under the United States Copyright Act of , no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. ISBN: MHID: The material in this eBook also appears in the print version of this title: ISBN: , MHID: eBook conversion by codeMantra Version All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill Education eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. To contact a representative please visit the Contact Us page at akperyatna.ac.id Notice Medicine is an ever-changing science. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy are required. The authors and the publisher of this work have checked with sources believed to be reliable in their efforts to provide information that is complete and generally in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical sciences, neither the authors nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in this work. Readers are encouraged to confirm the information contained herein with other sources. For example and in particular, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this work is accurate and that changes have not been made in the recommended dose or in the contraindications for administration. This recommendation is of particular importance in connection with new or infrequently used drugs. TERMS OF USE This is a copyrighted work and McGraw-Hill Education and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill Education’s prior consent. You may

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This atlas is dedicated to: My mother Late Raniba Diwan for teaching me the meaning of life My family Indira, Sneh, Kaushal, and Shira for their love and unconditional support My grandchildren Jonathon and Belen for bringing joy to our lives My friends and my mentors who supported me and guided me to the path of knowledge My co-editor Peter Staats for his unwavering friendship and being a trusted counselor And, Department of Anesthesiology and Pain Medicine Weill Cornell Medical College and New York Presbyterian Hospital of Cornell University For being an integral part of my personal and professional success Sudhir Diwan To Mom and Dad. You taught me how to change the world to make it a better place, one patient at a time, and more globally through theory and research. To my children, Alyssa, Dylan and Rachel. I am so proud of all three of you and the paths that you are forging. I am confident that each of you will make the world a better place in your own way. Most of all, to my wife Nancy, Thank you for your understanding and compassion. Your unwavering support has made this book possible. You make me, and everyone who knows you, a better person. Peter S. Staats

Contents Section Editors Contributors Preface Introduction

SECTION I: Basic Applications Mark J. Lema 1. Fluoroscopy in Interventional Pain Medicine David M. Schultz 2. Computed Tomography Guidance in Pain Management Ronil V. Chandra, Thabele-Leslie Mazwi, Daniel Oh, Albert J. Yoo, and Joshua A. Hirsch 3. Ultrasound Guidance for Interventional Pain Management Hariharan Shankar and Kanishka Rajput 4. Radiation Safety Vikram B. Patel 5. Equipment Used in Pain Management Vikram B. Patel 6. Corticosteroids: Indications, Pharmacology, and Risks in Interventional Pain Management Carolyn Kim and Christopher Gharibo 7. Local Anesthetics Christopher Voscopoulos and Mark J. Lema 8. Botulinum Toxins Charles E. Argoff and Howard Smith 9. Infection: Prevention, Diagnosis, and Management Dawood Sayed and Sudhir Diwan Anticoagulation Guidelines Nirmala R. Abraham, Cathy D. Trame, and Sudhir Diwan Sedation for Interventional Pain Procedures Nancy Staats EMG and Nerve Conduction Studies Bridget T. Carey Documentation, Billing, and Coding Laxmaiah Manchikanti

SECTION II: Head and Neck Injections Sudhir Diwan

Atlanto-Occipital Joint Injections Andrea Trescot Atlanto-Axial Joint Injections Andrea Trescot Cervical Nerve Root Blocks Stanley Golovac Trigeminal Ganglion and Nerve Block Miles Day and Kenneth D. Candido Sphenopalatine Ganglion Block Samer Narouze Occipital Nerve Blocks Andrea Trescot and Lawrence Kamhi Periorbital Nerve Blocks (Supraorbital, Supratrochlear, and Infraorbital Nerves) Sanford Silverman

SECTION III: Spinal Interventions Vikram B. Patel Interlaminar Epidural Steroid Injections: Cervical, Thoracic, Lumbar, and Caudal Raj Doshi, Vikram B. Patel, and Salahadin Abdi Transforaminal Epidural Steroid Injection Vikram B. Patel Facet Joint Interventions: Intra-Articular Injections, Medial Branch Blocks, and Radiofrequency Ablations Vikram B. Patel and Sukdeb Datta Lumbar Facet Joint Cyst Drainage and Injection Gerard P. Varlotta, Christopher Gharibo, and Z.T. Traeger Dorsal Root Ganglion Blocks and Radiofrequency Procedures Seth A. Waldman and Vladimir Kramskiy Sacroiliac Joint Injections Sheetal Kerkar Patil, Honorio T. Benzon, and Sudhir Diwan Sacroiliac Joint Denervation Using Synergy System Leonardo Kapural and Amanda Toye Sacroiliac Joint Denervation by Using Simplicity III Sudhir Diwan and Nimish Davé Percutaneous Sacroplasty Harold Cordner and Michael E. Frey Percutaneous Facet Fusion

Rinoo V. Shah Provocative Discogram Vikram B. Patel and Sudhir Diwan Percutaneous Disc Decompressions Sanjay Bakshi and Gerard W. Abrahamsen Hydrosurgery of Disc Didier Demesmin and Sagar Parikh Percutaneous Radiofrequency Discectomy With Disk IT Samyadev Datta and Vikram B. Patel Intradiscal Electrothermal Therapy Jason E. Pope and Nagy Mekhail Intradiscal Biacuplasty Mark Yelle and Leonardo Kapural Endoscopic Discectomy Sudhir Diwan, Kiran Patel, Kenneth Chapman, and Vikram B. Patel Minimally Invasive Lumbar Decompression (MILD procedure) Lora L. Brown Vertebral Augmentation Ramsin Benyamin, Ricardo Vallejo, Atiq Rehman, and Allen Burton Epidural Lysis of Adhesions Rinoo V. Shah Vascular Complications of Spinal Interventions Scott E. Glaser, Rinoo V. Shah, and Peter S. Staats

SECTION IV: Sympathetic Blocks Andrea Trescot Stellate Ganglion Block Richard S. Epter Thoracic (T) Ganglion Block Michael Stanton-Hicks Splanchnic Nerve Blocks Andrea Trescot Celiac Plexus Block Using CT Guidance Kenneth D. Candido and Nebojsa N. Knezevic Celiac Plexus Block Using Fluoroscopic Guidance Kenneth D. Candido, Peter S. Staats, Corey W. Hunter, and Sudhir Diwan Lumbar Sympathetic Block

Joshua P. Prager Superior and Inferior Hypogastric Plexus Blocks Agnes Stogicza Ganglion Impar Block Corey W. Hunter and Sudhir Diwan

SECTION V: Musculoskeletal Injections Vijay Vad Fluoroscopy and Ultrasound-Guided Joint Injections Jennifer Solomon, Christine Roque-Dang, and James Wyss Viscosupplements and Steroid Injections Jennifer Solomon and Vijay Vad Trigger Point Injections Ricardo A. Nieves and Rinoo V. Shah Neuroma Injections Rinoo V. Shah and Ricardo A. Nieves Myofascial Injections (Trigger Point, Piriformis, Iliopsoas, and Scalene Injections) Clark C. Smith, Farooq Khan, Juan Francisco Asenjo, and Honorio T. Benzon Intra-Articular Joint Injections Michael N. Brown Tendon Injections Robert Balch III

SECTION VI: Peripheral Nerve Blocks Christopher Gharibo Intercostal Nerve Block Amitabh Gulati Supraclavicular and Infraclavicular Nerve Blocks David B. Albert, Robert Altman, and Lisa Doan Ilioinguinal and Iliohypogastric Nerve Blocks Paul J. Hubbell III Genitofemoral Nerve Block Andrea Trescot Lateral Femoral Cutaneous Nerve Block Gerard P. Varlotta and Anya Myers Pudendal Nerve Block Susanti Chowdhaury, Gail Gray, and Andrea Trescot Obturator Nerve Block

Arthur Atchabahian Suprascapular Nerve Block Christopher Gharibo and Steve Aydin

SECTION VII: Intrathecal Drug Delivery Peter S. Staats Commercially Available Reservoir Options for Intrathecal Drug Delivery Corey W. Hunter and David Caraway Choosing Intrathecal Medication Philip S. Kim and Sudhir Diwan Intrathecal Drug Delivery Trialing Procedures Richard Bowman, Timothy R. Deer, and Jason E. Pope Permanent Implant Sean Li and Peter S. Staats

SECTION VIII: Neuroaugmentation Techniques Sudhir Diwan Spinal Cord Stimulation: Hardware Specifications Sudhir Diwan, Karina Gritsenko, and Neel Mehta Spinal Cord Stimulation: Trialing Procedure Richard B. North Spinal Cord Stimulation: Implantation Techniques Elias Veizi and Salim M. Hayek Anterograde Versus Retrograde Lead Placement Marshall D. Bedder Dorsal Root Ganglion Stimulation: Anatomy, Physiology, and Potential for Therapeutic Targeting in Chronic Pain Jeffery Kramer, Christine E. Draper, Timothy R. Deer, Jason E. Pope, Robert Levy, and Eric J. Grigsby Occipital Nerve Stimulation Erich O. Richter, Marina V. Abramova, and Kenneth M. Alo Percutaneous Peripheral Nerve and Field Stimulation Jason E. Pope, Timothy R. Deer, and Eric J. Grigsby Surgical Treatment of Trigeminal Neuralgia Michael G. Kaplitt

SECTION IX: Neurolytic Procedures Rinoo V. Shah Neurolytic Blocks Kenneth D. Candido and Nebojsa Nick Knezevic

Chemical Neurolysis Michael M. Bottros and Michael A. Erdek Cryoneuroablation David Irwin and Andrea Trescot Radiofrequency Neurolysis Anand Thakur and Peter S. Staats

Section Editors Section I: Basic Applications- Mark J. Lema, MD, PhD Professor and Chair of Anesthesiology of Anesthesiology, Critical Care, and Pain Medicine, Roswell Park Cancer Institute State University of New York at Buffalo School of Medicine Buffalo, New York Section II: Head and Neck Injections- Sudhir Diwan MD, DABIPP, FIPP Executive Director Manhattan Spine and Pain Medicine Associate Professor of Anesthesiology SUNY Downstate Medical Center Attending, Lenox Hill Hospital New York, New York Section III: Spinal Interventions- Vikram B. Patel, MD, FIPP, DABIPP Director, Phoenix Interventional Center for Advanced Learning Algonquin, Illinois Section IV: Sympathetic Blocks- Andrea Trescot, MD, ABIPP, FIPP Medical Director Pain and Headache Center Wasilla, Anchorage, Kenai, Alaska Section V: Musculoskeletal Injections- Vijay Vad, MD Assistant Professor Rehabilitation and Sports Medicine Weill Cornell Medical College Hospital for Special Surgery New York, New York Section VI: Peripheral Nerve Blocks- Christopher Gharibo, MD Associate Professor Department of Anesthesiology and Orthopedics New York University School of Medicine New York, New York Section VII: Intrathecal Drug Delivery- Peter S. Staats, MD, and MBA Adjunct Associate Professor Johns Hopkins University Department of Anesthesiology and Critical Care Medicine Premier Pain Centers, LLC

Shrewsbury, New Jersey Section VIII: Neuroaugmentation Techniques- Sudhir Diwan, MD, DABIPP, FIPP Executive Director Manhattan Spine and Pain Medicine Associate Professor of Clinical Anesthesiology SUNY Downstate Medical Center Pain Attending, Lenox Hill Hospital New York, New York Section IX: Neurolytic Procedures- Rinoo V. Shah, MD Clinical Professor of Anesthesiology Director, Chronic Pain LSU Health Science Center Shreveport, Louisiana

Contributors Salahadin Abdi, MD, PhD (Chapter 21) Professor and Chair Department of Pain Medicine—Unit The University of Texas MD Anderson Cancer Center Houston, Texas Nirmala R. Abraham, MD, FABPM (Chapter 10) Sycamore Pain Management Center Kettering Health Network Miamisburg, Ohio Gerard W. Abrahamsen, PA-C (Chapter 32) Physician Assistant, Manhattan Spine and Pain Medicine Physician Assistant, Lenox Hill Hospital New York, New York Marina V. Abramova, MD (Chapter 74) Department of Neurosurgery LSU Health Sciences Center New Orleans, Louisiana David B. Albert, MD (Chapter 58) Department of Anesthesiology NYU Langone Medical Center New York, New York Kenneth M. Alo, MD (Chapter 74) Pain Management, The Methodist Hospital Research Institute Houston, Texas Robert Altman, MD (Chapter 58) Associate Clinical Professor of Anesthesia NYU Medical School Director of Ambulatory Anesthesia Services NYU-HJD Director Regional Anesthesia Fellowship New York, New York Charles E. Argoff, MD (Chapter 8) Professor of Neurology, Albany Medical College Director, Comprehensive Pain Center, Albany Medical Center, Albany New York, New York Juan Francisco Asenjo, MD, FRCPC (Chapter 54)

Associate Professor Department of Anesthesia and Alan Edwards McGill Pain Treatment Unit McGill Cancer Pain Clinic McGill University Health Center Montréal, Quebec Canada Arthur Atchabahian, MD (Chapter 63) Associate Professor Department of Anesthesiology New York University School of Medicine New York, New York Steve M. Aydin, DO (Chapter 64) Clinical Assistant Professor in PM&R at Hofstra North Shore-LIJ School of Medicine, Manhassett, New York Director of Musculoskeletal Medicine at Manhattan Spine and Pain New York, New York Sanjay Bakshi, MD, D.A.B.P.M (Chapter 32) President, Manhattan Spine and Pain Medicine President, NY Society of Interventional Pain Physicians Attending Physician, Lenox Hill Hospital New York, New York Attending Physician, Beth Israel Medical Center New York, New York Attending Physician, Bayshore Medical Center Holmdel, New Jersey Member, International Spine Intervention Society New York, New York Robert Balch III, DO (Chapter 56) Diplomate of the American Board of PM&R Fellowship Trained and Board Certified in Pain Medicine Fort Worth, Texas Marshall D. Bedder, MD, FRCP (C) (Chapter 72) Director Interventional Pain Pacific Medical Centers (PacMed) Seattle, Washington Ramsin Benyamin, MD, DABIPP (Chapter 39) President, American Society of Interventional Pain Physicians President, Millennium Pain Center, Illinois Clinical Assistant Professor of Surgery, College of Medicine, University of Illinois, Urbana-Champaign

Illinois Honorio T. Benzon, MD (Chapters 26 and 54) Professor of Anesthesiology Northwestern University Feinberg School of Medicine Chicago, Illinois Michael M. Bottros, MD (Chapter 78) Assistant Professor of Anesthesiology and Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Washington University St. Louis School of Medicine St. Louis, Missouri Lora L. Brown, MD (Chapter 38) Medical Director TruWell, a new health Past President, Florida Society of Interventional Pain Physicians St. Petersburg, Florida Michael N. Brown, MD (Chapter 55) Private Practice Seattle, Washington Allen Burton, MD (Chapter 39) Houston Pain Centers Houston, Texas Kenneth D. Candido, MD (Chapters 17, 45, 46 and 77) Chairman, Department of Anesthesiology Professor of Clinical Anesthesiology-University of Illinois, Chicago Advocate Illinois Masonic Medical Center Chicago, Illinois David Caraway, MD, PhD (Chapter 65) Medical Director Center for Pain Relief, TriState, PLLC Huntington, West Virginia Bridget T. Carey, MD (Chapter 12) Assistant Professor of Neurology and Neuroscience, Weill Cornell Medical College New York, New York Ronil V. Chandra, MBBS, FRANZCR (Chapter 2) Neuroradiology and Neurovascular Surgery, Department of Imaging, Monash Health

Deer, MD (Chapters 67, 73 and 75) President and CEO, The Center For Pain Relief, and Clinical Professor of Anesthesiology, West Virginia University School of Medicine

Charleston, West Virginia Didier Demesmin, MD (Chapter 33) University Pain Management Center Somerset, New Jersey Sudhir Diwan, MD, DABIPP, FIPP (Chapters 9, 10, 26, 28, 31, 37, 46, 49, 65 and 69) Executive Director, Manhattan Spine and Pain Medicine Associate Professor of Clinical Anesthesiology SUNY Downstate Medical Center Pain Attending, Lenox Hill Hospital New York, New York Lisa Doan, MD (Chapter 58) Department of Anesthesiology NYU Langone Medical Center New York, New York Raj Doshi, MD (Chapter 21) Beth Israel Deaconess Medical Department of Anesthesia and Critical Care Boston, Massachusetts Christine E. Draper, PhD (Chapter 73) Spinal Modulation Menlo Park, California Richard S. Epter, MD, DABAPM, DABIPP, DABPM, FIPP (Chapter 42) Augusta Pain Center Augusta, Georgia Michael A. Erdek, MD (Chapter 78) Associate Professor of Anesthesiology, Oncology, and Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine Baltimore, Maryland Michael E. Frey, MD (Chapter 29) Advanced Pain Management and Specialist Fort Myers, Florida Adjunct Clinical Professor Virginia Commonwealth University Department of Physical Medicine and Rehabilitation Fort Myers, Florida Christopher Gharibo, MD (Chapters 6, 24 and 64)

Associate Professor Department of Anesthesiology & Orthopedics NYU School of Medicine New York, New York Scott E. Glaser, MD, DABIPP (Chapter 41) President, Pain Specialists of Greater Chicago, Board Member, American Society of Interventional Pain Physicians Chicago, Illinois Stanley Golovac, MD (Chapter 16) Florida Pain Merritt Island, Florida Gail Gray, ARNP (Chapter 62) Advanced Interventional Spine Consultants Largo, Florida Eric J. Grigsby, MD (Chapters 73 and 75) Founding Partner, Napa Pain Institute, Napa, California; Founder and President, Neurovations Napa, California Karina Gritsenko, MD (Chapter 69) Assistant Professor of Anesthesiology Regional Anesthesia, Interventional Pain Medicine Montefiore Medical Center Department of Anesthesiology New York, New York Amitabh Gulati, MD, FIPP (Chapter 57) Director of Ambulatory Pain Co-Director of the Cornell School of Medicine Pain Management Fellowship Assistant Attending Memorial Sloan Kettering Cancer Center New York, New York Salim M. Hayek MD, PhD (Chapter 71) Professor, Department of Anesthesiology Case Western Reserve University Chief, Division of Pain Medicine University Hospital Case Medical Center Cleveland, Ohio Joshua A. Hirsch, MD, FACR, FSIR (Chapter 2) Director: Interventional Neuroradiology and

Endovascular Neurosurgery Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts Paul J. Hubbell, III, MD, DDS (Chapter 59) Southern Pain and Anesthesia Metairie, Louisiana Corey W. Hunter, MD (Chapters 46, 49 and 65) Ainsworth Institute of Pain Management New York, New York David Irwin, DO (Chapter 79) Chief of Pain Medicine UPMC Hamot Medical Center Erie, Pennsylvania Lawrence Kamhi, MD, FIPP (Chapter 19) Spine and Interventional Pain Management Warwick, New York Michael G. Kaplitt, MD, PhD (Chapter 76) Director of Stereotactic and Functional Neurosurgery and Vice-Chairman for Research Department of Neurological Surgery Weill Cornell Medical College New York, New York Leonardo Kapural, MD, PhD (Chapters 27 and 36) Professor of Anesthesiology, Wake Forest University School of Medicine Carolinas Pain Institute and Center for Clinical Research Winston-Salem, North Carolina Farooq Khan (Chapter 54) Private Practice Chicago, Illinois Carolyn Kim, MD (Chapter 6) Department of Anesthesiology NYU Langone Medical Center New York, New York Philip S. Kim, MD (Chapter 66) Medical Director, Center for Interventional Pain Spine LLC Newark, Delaware

Nebojsa Nick Knezevic, MD, PhD (Chapters 45 and 77) Director of Anesthesiology Research Clinical Assistant Professor-University of Illinois, Chicago Department of Anesthesiology Advocate Illinois Masonic Medical Center Chicago, Illinois Jeffery Kramer, PhD (Chapter 73) Spinal Modulation, Menlo Park, California Department of Pharmacology and Cancer Biology University of Illinois Peoria, Illinois Vladimir Kramskiy, MD (Chapter 25) Director, Ambulatory Recuperative Pain Medicine Attending, Pain Medicine, Neurology Hospital for Special Surgery New York, New York Mark J. Lema, MD, PhD (Chapter 7) Professor and Chair of Anesthesiology, Critical Care, and Pain Medicine, Roswell Park Cancer Institute, State University of New York at Buffalo School of Medicine Buffalo, New York Robert Levy MD, PhD (Chapter 73) Professor of Neurosurgery, College of Medicine-Jacksonville, University of Florida Jacksonville, Florida Sean Li, MD (Chapter 68) Premier Pain Centers, LLC Shrewsbury, New Jersey Laxmaiah Manchikanti, MD (Chapter 13) Medical Director, Pain Management Centers, Paducah Kentucky Clinical Professor of Anesthesiology and Perioperative Medicine, University of Louisville Louisville, Kentucky Thabele-Leslie Mazwi, MD (Chapter 2) Departments of Interventional Neuroradiology and Endovascular Neurosurgery Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts Neel Mehta, MD (Chapter 69) Medical Director, Division of Pain Medicine Assistant Professor of Anesthesiology Weill Cornell Medical College

New York Presbyterian Hospital New York, New York Nagy Mekhail, MD, PhD (Chapter 35) Cleveland Clinic Pain Management Department Cleveland, Ohio Anya R. Myers, DO (Chapter 61) Department of Rehabilitation Medicine NYU Langone Medical Center Rusk Institute of Rehabilitation Medicine Jersey City, New Jersey Samer Narouze, MD, PhD (Chapter 18) Professor and Chairman Pain Management Department Summa Western Reserve Hospitals Cuyahoga Falls, Ohio Ricardo A. Nieves, MD, FAAPMR (Sub Pain, Sub Sports Med), FIPP, DABIPP (Chapters 52 and 53) Colorado Spine, Pain and Sports Medicine, P.C. Fort Collins, Colorado Richard B. North, MD (Chapter 70) Professor of Neurosurgery, Anesthesiology and Critical Care Medicine (ret.) School of Medicine, John Hopkins University Brooklandville, Maryland Daniel Oh, MD (Chapter 2) Departments of Interventional Neuroradiology and Endovascular Neurosurgery Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts Sagar Parikh, MD (Chapter 33) University Pain Management Center Somerset, New Jersey Kiran Patel, MD (Chapter 37) Attending, Pain Management Staten Island University Hospital Staten Island, New York Vikram B. Patel, MD, FIPP, DABIPP (Chapters 4, 5 21, 22, 23, 31, 34 and 37) Director, Phoenix Interventional Center for Advanced Learning

Algonquin, Illinois Sheetal Kerkar Patil, MD (Chapter 26) Clinical Associate of Anesthesia and Pain Medicine University of Chicago Chicago, Illinois Jason E. Pope, MD (Chapters 35, 67, 73 and 75) Director, Intrathecal Therapeutics, The Center for Pain Relief, Charleston, West Virginia Medical Director, Pain Relief Center Teays Valley, West Virginia Joshua P. Prager, MD, MS (Chapter 47) Director, Center for the Rehabiliation of Pain Syndromes (CRPS) at UCLA Medical Plaza Immediate Past Chair, Complex Regional Pain Syndrome Group of the International Associate for the Study of Pain (IASP) Senior Advisor to the Board of the North American Neuromodulation Society (NANS) Departments of Anesthesiology and Internal Medicine David Geffen School of Medicine at UCLA Los Angeles, California Kanishka Rajput MD (Chapter 3) Senior Resident, Department of Anesthesiology Medical College of Wisconsin Milwaukee, Wisconsin Atiq Rehman, MD (Chapter 39) Houston Pain Centers Houston, Texas Erich O. Richter, MD (Chapter 74) Department of Neurosurgery LSU Health Sciences Center, New Orleans New Orleans, Louisiana Christine Roque-Dang, DO, FAAPMR (Chapter 50) Director of Physiatry and Attending Physiatrist Bergen Medical Associates Emerson, New Jersey Dawood Sayed, MD (Chapter 9) Assistant Professor of Anesthesiology and Pain Medicine The University of Kansas Medical Centre Kansas City, Kansas David M. Schultz, MD (Chapter 1) Founder and Medical Director Medical Advanced Pain Specialists (MAPS)

Edina, Minnesota Rinoo V. Shah, MD (Chapters 30, 40, 41, 52 and 53) Clinical Professor of Anesthesiology Director, Chronic Pain LSU Health Science Center Shreveport, Louisiana Hariharan Shankar, MD (Chapter 3) Associate Professor, Department of Anesthesiology Medical College of Wisconsin Clement Zablocki VA Medical Center Milwaukee, Wisconsin Sanford Silverman, MD (Chapter 20) Comprehensive Pain Medicine Immediate Past President, Florida Society of Interventional Pain Physicians (FSIPP) President-Elect Broward County Medical Association Pompano Beach, Florida Clark C. Smith, MD MPH (Chapter 54) Department of Rehabilitation and Regenerative Medicine Columbia University New York Presbyterian Hospital Columbia University Medical School New York, New York Howard Smith, MD Medical Director, Palliative medicine Academic Director, Pain Management Department of Anesthesiology Albany Medical Center Albany, New York Jennifer Solomon, MD (Chapters 50 and 51) Assistant Professor Rehabilitation and Sports Medicine Weill Cornell Medical College Assistant Attending Hospital for Special Surgery New York, New York Nancy Staats, MD (Chapter 11) Advanced Endoscopy and Surgery Center Eatontown, New Jersey

Peter S. Staats, MD, MBA (Chapters 41, 46, 68 and 80) Adjunct Associate Professor Johns Hopkins University Department of Anesthesiology and Critical Care Medicine Premier Pain Centers, LLC Shrewsbury, New Jersey Michael Stanton-Hicks, MD (Chapter 43) Staff Institute of Anesthesiology Department of Pain Medicine Institute of Neurological Restoration Shaker Pediatric Rehabilitation Program Cleveland Clinic Cleveland, Ohio Agnes Stogicza, MD (Chapter 48) Anesthesiologist and Pain Physician University of Washington Harborview Medical Center Seattle, Washington Anand Thakur, MD (Chapter 80) Clinical Assistant Professor Department of Anesthesiology Wayne State University School of Medicine Detroit, Michigan Z.T. Traeger, DO (Chapter 24) Department of Rehabilitation Medicine NYU School of Medicine Rusk Institute of Rehabilitation Medicine New York, New York Cathy D. Trame, RN, MS, CNS, BC (Chapter 10) Sycamore Pain Management Center Kettering Health Network Miamisburg, Ohio Andrea Trescot, MD, ABIPP, FIPP (Chapters 14, 15, 19, 44, 60, 62 and 79) Medical Director Pain and Headache Center Wasilla, Anchorage, Kenai, Alaska Amanda Toye, MD (Chapter 27) Baylor University Medical Center at Dallas

Center for Pain Management Dallas, Texas Vijay Vad, MD (Chapter 51) Assistant Professor Rehabilitation and Sports Medicine Weill Cornell Medical College Hospital for Special Surgery New York, New York Gerard P. Varlotta, DO, FACSM (Chapters 24 and 61) Associate Professor, Departments of Orthopaedic Surgery & Rehabilitation Medicine NYU School of Medicine, Rusk Institute of Rehabilitation Medicine New York, New York Elias Veizi MD, PhD (Chapter 71) Assistant Professor Division of Pain Medicine Case Western Reserve University Pain Medicine & Spine Care Cleveland Veterans Affairs Medical Center Cleveland, Ohio Ricardo Vellejo, MD, PhD (Chapter 39) Director of Research, Millennium Pain Center Medical Director, UnityPoint Methodist Comprehensive Pain Center, Peoria, Illinois Adjunct Professor, Biology Department, Illinois State University, Normal, Illinois Chief Editor, Techniques in Regional Anesthesia and Pain Management. Christopher Voscopoulos, MD (Chapter 7) Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School Boston, Massachusetts Seth A. Waldman, MD (Chapter 25) Director, Division of Pain Management Hospital for Special Surgery Clinical Assistant Professor, Anesthesiology Weil Medical College of Cornell University New York, New York James Wyss, MD, PT (Chapter 50) Assistant Attending Physiatrist Associate Fellowship Director Physiatry Department

Hospital for Special Surgery Assistant Professor of Clinical Rehabilitation Medicine Weill Cornell Medical College New York, NY Mark Yelle, MD, PhD (Chapter 36) Chronic Pain Medicine Center at Wake Forest University Baptist Health and Carolinas Pain Institute Winston-Salem, North Carolina Albert J. Yoo, MD (Chapter 2) Departments of Interventional Neuroradiology and Endovascular Neurosurgery Department of Diagnostic Neuroradiology Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts

Preface The field of interventional pain management is a forever evolving field. There are new developments occurring daily with new approaches and new equipment that make therapies safer and more effective. This book gives clinical pearls on strategies that we use in interventional pain management. It has been designed as an easy-to-use source for most of the interventional pain specialists needs. It is not intended to replace a comprehensive fellowship in pain management. The pros and cons of medications, the psychological approaches effective in pain, as well as the comprehensive use of rehabilitation and complementary approaches are simply not covered. This book, however, does provide the physician with relevant anatomy and should prompt a thoughtful approach to specific pain syndromes and what causes them. Many years ago, patients with pain referred to as having “chronic pain syndrome” or sometimes were maligned with pejorative terms. Patients were called malingerers, assumed to have major psychiatric disorders or were assumed to be drug seeking. While all of these certainly occur, I believe patients with legitimate medical problems were frequently misdiagnosed. This occurred because there was not an adequate training of physicians to diagnose and treat complex pain disorders. To date, many physicians have inadequate training in recognizing complex medical and neurologic disorders, and many syndromes are missed. In previous decades there were a few procedures that were commonly performed. Epidurals, Trigger points, and major joint injections were common. Complex procedures were rarely performed. Medications were (and still are) a mainstay of a comprehensive pain practice. While we today still use these classes of analgesics, we are now recognizing that the medication approach is not without risks. The use of opiates has increased dramatically over the past twenty years. With this we have seen a dramatic rise in deaths attributed, at least in part to the use of prescription analgesics. It was estimated that in there were over 16 thousand deaths with a prescription opioid as at least a part of the problem. Pain management is not just about giving a patient drugs. It is about making an accurate diagnosis, developing a therapeutic plan, and devising a minimally invasive approach when possible to effectively treat or manage the problem. The Diwan–Staats Atlas puts together what we know about various pain states, along with the most current information in anatomy and pathophysiology. We concentrate on the most minimally invasive techniques available, thereby enhancing safety. This book is really the “how to” of current interventional pain management; however, it does not address the ”when to.” The “when to” involves clinical judgment, careful evaluation, and individual case-specific issues, along with evidencebased medicine and an assessment of the risks, benefits, and alternatives of all interventional procedures. Summarizing all the available clinical trials would have been beyond the scope of a single volume. There are so many leaders and influential figures that have helped the development of this field. Dr. Bonica, Dr. Stanton Hicks, Dr. Gabor Racz, Dr. Prithvi Raj, and Dr. Lax Manchikanti are a few who have devoted so much of their life to advancing the specialty of interventional pain. On behalf of the millions of pain sufferers and the physicians you have taught, we thank you. We would like to express our deep appreciation to so many individuals. First, we must thank the section editors, Drs. Lema, Patel, Trescot, Vad, Gharibo, and Shah who have gone above and beyond, reviewing and re-reviewing the chapters. Thank you to our numerous authors who have created such wonderful original works. The synthesis of all of your works has made this volume special. With all of the talk about evidence-based medicine, and the needs for multiple randomized controlled trials to support reimbursement, and the battles in the halls of Congress, and the battles with insurers, we sincerely hope that this book will help physicians help patients, as safely and effectively as possible.

That’s why we all do what we do.

Introduction EVIDENCE-BASED MEDICINE Peter S. Staats and Sudhir Diwan “Doctors are men who give drugs of which they know little, into bodies of which they know less, for diseases of which they know nothing at all.” Voltaire s For thousands of years, however, physicians blithely administered a variety of concoctions intended to treat pain; a few worked, many eventually fell by the wayside; and others were reluctantly abandoned when they failed to stand up to rigorous therapeutic analysis. Thus, although healers throughout antiquity accurately touted the efficacy of opium, now known to contain the potent analgesic morphine, and of willow bark, which is the source for aspirin, dusty tomes also contain scores of therapeutic recommendations that have little merit in the management of pain. The Skillful Physician, the mainstay of seventeenth-century medicine, unequivocally recommends applying hot goose oil to treat sciatica.

The Concept Evidence-based medicine, the concept that physicians should use the best available data to guide ones practice, has become the mainstay in modern medicine. Comparative effectiveness research, comparing two accepted strategies to determine which therapies are the most effective, is widely being considered the standard.

The Flaws and Frustrations While no one can argue that physicians should use the best “available data to guide the practice,” the concept is now being misinterpreted and distorted largely by insurers and other carriers to deny appropriate care. Years ago, the same week the media reported the CEO of a major health care insurance company’s compensation package of over a billion dollars, one of the authors (PSS) was called to emergently evaluate a patient (with previous back surgery in the ICU) with a lumbosacral radiculopathy with this insurance. The request was specifically for an epidural lysis of adhesions procedure. After a thorough evaluation it was felt to be a reasonable approach, and the procedure was performed successfully. The next day his pain was under control for the first time in weeks, we facilitated discharge, there was great patient and hospital satisfaction and, we succeeded in saving the insurance company money since he was discharged from the hospital. The insurance company never paid for this procedure and claimed that the therapy offered was experimental. This was in spite of four double-blind randomized controlled trials demonstrating the efficacy of this therapy. The denial was appealed which was reviewed by the insurance company’s “appeal committee” that included three physicians: a gynecologist, a neurologist, and a general surgeon. None of whom had heard of an epidural lysis of adhesions procedure. Not surprisingly the committee upheld the denial of the insurance carrier, indicating that there was no “evidenced-based medicine” supporting the claim. Of course, this was patently untrue, but does highlight several problems that can occur with evidence-based medicine if they are not judiciously applied.

Problems With Evidence-Based Medicine • EBM is limited to clinical research only, and does not correlate well to the clinical expertise. • It presents a “cookbook” approach to practice medicine. • The clinical evidence should be a source of information, not a replacement of individual clinical expertise. • Insurance industry uses this concept as a cost-effective (cost-cutting) tool, and ignores patient’s values and preferences. • It promotes a state of mind that is analogous to ivory-tower, whereby the insurers define the care path. • Continued concern of EBM being hijacked by purchasers and insurance managers to cut costs. Many physicians have received similar frustrating denials from insurance companies claiming the procedures or medications being offered are experimental. We receive these denials with discography, epidural steroids, therapeutic occipital nerve blocks, radiofrequency ablations of facet joints, spinal cord stimulation to name a few, claiming that each of the above is “experimental.” It became clear that the insurers are using the rationale of “no evidence-based medicine” to selectively deny high-cost procedures, or procedures insurers have felt have been abused.

Conflicts With Common Sense • Quantitative research from randomized controlled trials (RCTs) may not be relevant to all treatments in all situations. • The EBM is a slow, lengthy, and expensive process that will take years before the evidence is produced and applied to the clinical practice. • RCTs may restrict under-researched racial minorities and patients with comorbid diseases from practice of EBM. • RCTs apply to only the group of people that are included in the studies, and do not address the individualized treatment plans based on physicians’ personal experience and knowledge.

Historical Perspective on Evidence-Based Practice • In the s, there were very few double-blind randomized controlled trials demonstrating efficacy of any number of therapies. • Medical decisions were largely made on the basis of clinical intuition pathophysiology and clinical experience. • There were few large studies, and the results of large clinical trials were rarely used to modify or change clinical practice paradigms. • In the s, physicians began to realize that that a higher standard was required. Evidence-based medicine and evidence-based practice were born.

What Is Evidence-Based Medicine? Evidence-based practice is “the conscientious, explicit and judicious use of current best evidence in

making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research.” (Sackett D, ) • Evidence-based medicine and guidelines that use evidence-based medicine are involved in synthesizing the available published data to come up with the most effective approach to care. • The available data is graded in a hierarchal fashion. • Large double-blind randomized controlled trials receive the highest grade, followed by prospective studies and retrospective reviews and even case reports and opinions of experts are graded. • If an approach has a large number of well-designed randomized controlled trials supporting its use, the approach is given a high grade. • If there are no well-designed trials, and the physician’s experience is touted as the only rationale for proceeding with a therapy, a low grade is given.

Source and Synthesis of Evidence • Basic science studies on and animal research: Very first step to produce evidence. • Case reports and case series: Reports of treatment of individual cases or case series without control groups, with a little statistical validity. • Case-control studies: Studies with a specific condition are compared with people without the condition. These studies are less reliable than randomized controlled trials and cohort studies. • Cohort studies: A group of patients treated with a particular treatment and followed for an extended period, and then compared their outcomes with a similar group that has not been treated with the similar treatment. • Randomized controlled trials: Carefully planned methodologies to randomize and blind the researcher and the patient to reduce a potential bias while comparing the interventional (treated) and control (untreated) groups. These studies provide the best evidence with high statistical validity. • Systemic reviews: An extensive literature search is conducted to identify studies with sound methodology focused on a specific treatment or procedure. The studies are reviewed for quality and results are summarized based on predetermined criteria. • Meta-analysis: It is a large study to mathematically combine results of a number of very valid studies that have used accepted standards of statistical methodology.

Levels of Evidence United States Preventive Services Task Force (USPSTF) has developed systems to stratify evidence by its quality for ranking evidence about the effectiveness of the treatment: • Level I: Evidence obtained from at least one properly designed randomized controlled trials • Level II Evidence obtained form well-designed controlled trials without randomization • Level II Evidence obtained from well-designed multicenter cohort or case-control analysis • Level II Evidence obtained from multiple studies with or without intervention including uncontrolled trials

• Level III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees

Levels of Recommendations The risks versus benefits ratio obtained from the evidence available in literature, USPSTF uses following levels of recommendations for clinical service or treatments. • Level A: Good scientific evidence to suggest substantial benefits outweigh the potential risks • Level B: Fair scientific evidence to suggest the clinical benefits outweigh the potential risks • Level C: Fair evidence to suggest clinical benefits, but the ratio of benefits to risks is too close to make recommendations • Level D: Fair scientific evidence to suggest that risks of clinical service clearly outweigh the potential benefits • Level I: The scientific evidence is either lacking, or poor quality, or conflicting to assess the risks of clinical service to potential benefits

Problems With Evidence-Based Medicine (EBM) There are several problems with using evidence-based medicine to guide all care in pain management or the development of guidelines. Frequently studies are funded by industry, either pharmaceutical or medical device companies. Those are the companies with the money to spend on demonstrating the efficacy of large clinical trials. These studies may have potential conflict of interest, but there is no funding otherwise to conduct studies. • There is a shortage of coherent and consistent scientific studies to produce evidence. • The insurance companies obtain the evidence to their advantage from nonindexed journals with non–peer-reviewed articles, and ignore the good evidence published in indexed journals. • The evidence is often reviewed by the physicians who do not have hands-on experience of particular procedures, eg, a neurologist who never performed an epidural steroid injection, writing the guidelines for epidural steroid injections based on evidence. • The poorly written guidelines produced by the “so-called” experts with vested produce barriers to the practice of high-quality medicine.

Expensive Proposition Double-blind randomized controlled trials are widely considered the gold standard for study design. The paucity of evidence is largely due to paucity of good studies, and the cost is a big factor. • New drug applications for the FDA require multiple studies. • It has been estimated cost close to a billion dollars to get a new drug approved through the FDA. • Each study costs millions to perform. • For this reason, many well-designed studies do not come from physicians as sponsors, looking at old drugs or new approaches to pain. Companies with significant financial resources, that stand to make financial gain if their drug or

product is successful, are motivated to fund large-scale clinical trials to demonstrate efficacy of their product. Older inexpensive drugs, that may be off patent, may be just as effective as a new drug but will not be studied in large-scale clinical trials and will be given a low score in an EBM approach.

Different Standards Limitations for Studies Regarding Interventional Procedures • Physicians do not have the financial wherewithal to pay for the studies requested by the insurers. • Few physicians have the time and expertise to apply for federal funding to perform these studies. • Infrequently performed procedures may be cost effective (ie, thoracic epidurals) but have no medical device company funding the studies. There will be a paucity of data supporting their use. • For these reasons, many insurers are denying interventional procedures under the guise of “evidence-based medicine.” • Different standards: They site lack of randomized double-blind controlled trials as a rationale for noncoverage, but allow surgical procedures that have not been subjected to the same rigor as many of the interventional therapies discussed in this book.

Our perspective is that there has been an explosive growth in our field, associated with abuse. We as a society and the payers, need to establish reasonable reimbursement criteria and follow those with poor outcome, not to blanketly deny care.

Many Intricacies in Doing the Procedures If one does not do the procedure exactly the same as another, there will be inconsistencies and results will vary. For example, the difficulty in determining the efficacy of epidural steroids will be influenced by the following factors. • Blind procedures versus fluoroscopically guided procedures. • Transforaminal versus Interlaminar. • Cervical epidurals versus thoracic epidurals. • The quality of pain may vary. • The severity of the pain may be poorly controlled for. • Coexisting diseases such as obesity or diabetes may influence the outcome. • The doses and types of steroids may vary between practitioners. • The technique may vary on precisely where the needle is placed. • The use or amount of local anesthetics used may vary greatly.

Level of Skills and Experience Inexperienced physicians may perform a procedure under fluoro guidance but may not have the same expertise in guiding the needle to the exact position as well-experienced physician who has spent years perfecting this approach. Thus taking one very simple examples one can see that physicians outcomes would be expected to vary greatly. Some physicians routinely do one procedure while others do a series of injections.

Varieties in Indications for Procedures The indications may vary for a variety of techniques being performed for patients with: • Herniated disc versus stenosis. • Radiculopathy versus axial back pain. • Epidural steroids may be used for CRPS, radiculopathy, or postherpetic neuralgia. • Difference in rates of traditional insurance versus workman’s compensation. Accordingly many small studies may not represent the exact patient population being studied. While it is important for the physician to remain conversant with the literature, it is important to continually individualize the therapy for that specific case.

Comparative Effectiveness Research Comparative effectiveness research (CER) is the direct comparison of existing health care interventions

to determine: • Which treatment works best for which patients • Which treatment poses the greatest benefits and harms • The core question of CER in which treatment works best, for whom, and under what circumstances It is more of a pragmatic approach that attempts to compare a variety of reasonable interventions in determining the most appropriate strategy.

Cost-Effectiveness Analysis Cost-effectiveness analysis (CEA) is a form of economic analysis that compares the relative costs and outcomes (effects) of two or more courses of action. CEA is distinct from cost-benefit analysis, which assigns a monetary value to the measure of effect. CEA is often used in the field of health services, where it may be inappropriate to monetize health effect.

Guideline Development Guidelines on the appropriate steps in the management of various diseases have become a useful tool for physicians. • The guidelines synthesize the evidence-based medicine, the well-designed studies that have been done. • More studies on a particular therapy or drug it is more likely to receive a favorable position in the guideline development. • Guidelines which attempt to synthesize evidence-based medicine in to clinical paradigms, count the number of evidence-based studies, and make recommendations based on the total number of patients and number of studies in the literature. • Those with better financial resources may increase the total number of studies that will lead to a pharmaceutical or medical device approach. This type of weighted research will favor more expensive therapies that are frequently funded by pharmaceuticals and medical device companies. • The guideline development itself may be insidiously influenced by medical device and pharmaceutical companies as they tend to fund those guidelines that support their development. • Some insurers have begun funding the development of guidelines, and they tend to weigh more heavily noninterventional therapies, in spite of a demonstrated lack of efficacy.

Conclusions This text is an atlas of interventional pain medicine. We espouse Sackets original tenets, of using the best available evidence, as well as those of Hippocrates to do no harm. We recognize that the practice of medicine takes an individual approach to the management of pain. We do believe that a rationale physician, when faced with limited data, may try therapies that make sense. The text that follows is more of a “how to” approach. The denial of appropriate care by insurers when there is a paucity of date on a specific approach, indicating that there is no evidence-based medicine flies in the face of what evidencebased medicine is about. Evidenced-based medicine allows the physician to understand the literature, its pitfalls, and extrapolate based on their clinical experience in determining the most appropriate course of

action.

Suggested Reading Agency for health care policy and research. akperyatna.ac.id Evidence-based medicine—Wikipedia, the free encyclopedia. Sackett D. Evidence-based medicine: what it is and what it isn’t. BMJ. ; akperyatna.ac.id Staats PS. Introduction. In: Aronoff G, ed. The Pharmacologic Management of Pain Task Force Ratings. akperyatna.ac.id

SECTION I

BASIC APPLICATIONS

CHAPTER 1

Fluoroscopy in Interventional Pain Medicine David M. Schultz Since their discovery in , x-rays have revolutionized the practice of medicine. By allowing doctors to view the inside of the living body, x-rays have greatly increased our ability to diagnose and treat disease and to precisely deliver targeted therapies. The fluoroscope was the first x-ray machine and has evolved from its humble beginnings into a powerful and sophisticated device that has become the basis for the new field of interventional pain management. Modern fluoroscopes enable the interventional pain practitioner to use continuous, real-time x-ray imaging to guide interventional procedures that target the physical generators of pain with a high degree of precision and safety. Since fluoroscopy is essential for most invasive pain procedures, it is imperative that interventional pain physicians have a firm understanding of the fluoroscope in order to use it safely and effectively in daily practice.

HIGHLIGHTS IN THE HISTORY OF FLUOROSCOPY • German physicist Wilhelm Roentgen discovers x-rays and takes the first fluoroscopic image, purportedly of his wife’s hand, winning the Nobel Prize in Physics for his efforts. • Thomas Edison invents the first fluoroscope, which is quickly adopted for medical uses. • Madame Curie discovers radium, which is then used to illuminate games of chance in New York City. • The inappropriate, nonmedical use of fluoroscopy becomes increasingly common. • Compensation is awarded in the first medical malpractice suit involving x-ray injury. • Radiation injuries become increasingly common, and practitioners become increasingly aware of the dangers of x-ray exposure. • After several years of practice, radiology pioneer Dr. Mihran Kassabian suffers severe radiation burns to his hands and ultimately dies of radiation-induced cancer at age • The National Council on Radiation Protection and Measurement (NCRP) is created to protect patients, healthcare workers, and the public from the harmful effects of radiation. • Patient injuries resulting from excessive use of fluoroscopy during medical procedures prompt the FDA to issue a Public Health Advisory.1

THE PHYSICS OF X-RAYS X-rays are a form of ionizing radiation that can be created in the fluoroscope and harnessed for medical imaging. X-rays are produced in the x-ray tube of the fluoroscope, which contains a cathode and metal anode. • When high-velocity electrons leave the cathode and collide with the metal anode, the kinetic energy contained within the electrons is converted to electromagnetic energy and released in the form of xrays. • X-rays are close to light photons on the electromagnetic spectrum but have shorter wavelength and higher energy (Figure ).

Figure X-rays are close to light photons on the electromagnetic spectrum but have shorter wavelength and higher energy. The x-rays produced by the x-ray tube are directed through body tissues. When these x-rays contact

matter, they interact in one of three ways: 1. They are absorbed. 2. They are deflected and scattered. 3. They pass through matter unheeded. Since x-rays are a form of ionizing radiation, they interact with certain media in ways that allow the human eye to view their presence. In fluoroscopy, the x-rays cause the phosphorous in a fluorescent screen to emit visible light. Modern fluoroscopic systems use zinc-cadmium sulfide as an effective phosphor. The fluoroscopic image is essentially composed of shadows created as body tissues of various densities preferentially absorb x-rays. As the density of matter increases, x-rays are absorbed or scattered to a greater extent, giving rise to the 5 radiologic densities commonly used to describe radiographs: 1. Air 2. Fat 3. Water (soft tissue) 4. Bone 5. Metal Air allows most emitted x-rays to penetrate through to the underlying imaging medium. Bone and metal are denser and absorb or deflect x-rays, allowing fewer x-rays to penetrate through to the imaging medium. Consequently, higher-density tissues cast shadows that appear darker on the displayed image because the x-rays contacting the phosphor create light (Figure ). This is in contrast with traditional xray imaging, which uses a photographic plate to capture the effects of photons (Figure ). The plate starts out as a white background that is exposed by the x-rays reaching it. The fluoroscopic image is analogous to the photographic negative whereas the developed x-ray film is analogous to the photograph.

Figure Fluoroscopic image with higher density structures appearing darker; note the bubbles of air contained within the injected x-ray contrast medium.

Figure Plain chest radiograph with denser tissues appearing lighter. (Reprinted with permission from Fuster V, Walsh RA, Harrington RA: Hurst’s The Heart, 13th Edition: akperyatna.ac.id © The McGraw-Hill Companies, Inc. All rights reserved.)

THE C-ARM FLUOROSCOPE The primary function of the fluoroscope is to generate a controllable beam of x-rays that can be directed through tissue and then captured on a viewing medium to form a visible image. Interventional pain physicians commonly use the C-arm fluoroscope because of its maneuverability and compact design (Figure ).

Figure Modern fluoroscope with a shielded x-ray tube contained within a movable C-arm. The main components of a typical mobile C-arm fluoroscope include the x-ray generator, x-ray tube, collimator, image intensifier, optical coupling chain and viewing monitor (Figure ).

Figure Modern fluoroscope with components labeled. The x-ray generator converts alternating current to high voltage direct current, which is delivered to the x-ray tube. • The current determines the number of x-rays produced by the x-ray tube and therefore controls the density and intensity of the x-ray beam. • The voltage determines the energy of the x-rays produced and the penetrating ability of the x-ray beam. • The current and voltage can be automatically or manually adjusted from the base unit of the fluoroscope (Figure ).

Figure The amount of current supplied to the x-ray tube is measured in milliamps (mA) and determines the density and intensity of the x-ray beam. The x-ray tube is housed in one end of the C-arm and is balanced by the image intensifier at the other end. • The beam that is released from the x-ray tube diverges as it moves toward the image intensifier. • The x-ray beam is most concentrated as it exits the x-ray tube at the center point aperture. • Severe patient injuries occur when body tissue remains in close proximity to the origin of the x-ray beam for prolonged periods.2 Fluoroscopic images are dim and difficult to view without some mechanism to brighten the viewable image. The image intensifier was introduced in and functions to convert x-rays into light photons,

which amplify brightness by to 20,fold. Collimation allows the fluoroscope operator to reduce the size and shape of the x-ray beam to better conform to the field of view (Figures and ). As the fluoroscope moves across areas of varying body tissue density, the collimator automatically adjusts the x-ray beam to conform to the viewing field. The operator can also adjust the collimation window manually to conform to a region of clinical interest (Figure ). • By reducing the x-ray beam to include only the tissue targeted for viewing, less tissue is irradiated, and patient exposure to radiation is reduced. In addition, there is less scattered radiation exposure to personnel in the room. • Unattenuated x-rays also cause glare on the image screen resulting in poor image quality. Collimation reduces glare and improves the clarity of the image.

Figure Without collimation, the x-ray beam is not optimized to fit the field of view, and there is a large amount of scattered radiation from the patient and table as well as a monitor image that is relatively degraded.

Figure By using collimation, the x-ray beam is shaped to better fit the field of view resulting in fewer x-rays leaving the x-ray tube, less scatter radiation, and a clearer image on the monitor.

Figure Controls for both radial (iris) and rectangular collimation on a typical C-arm fluoroscope. To process the images that have been brightened by the image intensifier for optimal viewing, modern fluoroscopic systems incorporate optical coupling chains that route the image signal to a video camera. Optical coupling enables the x-ray image to be viewed via closed-circuit television, displaying realtime video imaging of continuous fluoroscopy. A typical mobile C-arm fluoroscope can also display simultaneous static images on a second television monitor for viewing of the last image in a video sequence. This “last image hold” capability allows the interventionalist to minimize radiation exposure by performing procedures that utilize a series of static images to follow needle placement. Using digital image conversion technology, analogue video signals are digitized and stored in computer memory. Using less radiation, subsequent digital enhancement of the fluoroscopic image can achieve image clarity approaching that of x-ray film. Digital images can also be quickly and conveniently distributed via computer networks and stored on computer workstations or archived into various digital storage media for later retrieval. Since materials of differing density cause x-rays to be absorbed or deflected to varying degrees, fluoroscopy table and pad materials with high or inconsistent density can result in poor image quality. • Denser materials in table and pad attenuate x-rays, which will result in increased patient radiation exposure and loss of image contrast.

• Materials that are inconsistent in density tend to cast artifactual shadows on the imaging screen. It is therefore imperative to use only x-ray tables and pads designed to optimize fluoroscopic imaging. Newer composite materials such as carbon fiber in fluoroscopy tables provide adequate strength to support large patients while minimizing x-ray attenuation and distortion. Likewise, thin foam pads overlying the table have minimal effect on x-rays, but large gel supports or irregularly folded pillows may create significant x-ray attenuation, distortion, and artifact. A diving-board table configuration allows for easier imaging of upper body structures during interventional pain procedures.

RADIATION SAFETY Exposure to ionizing radiation—including x-rays—can result in the formation of free radicals that cause damage to cell structures. • Chemical chain reactions may trigger changes in cell membrane permeability, resulting in cellular dysfunction. • Damage to DNA may cause somatic mutations, causing harm to subsequent generations. • Radiation protection standards are designed to prevent unintended radiation and to maintain exposure for therapeutic purposes “As Low As is Reasonably Achievable” (ALARA). Dosimetry badges are solid-state radiation detection devices used to measure cumulative radiation dose. For optimal monitoring, two badges are worn, one inside and one outside of a protective lead apron, to determine both overall exposure and the efficacy of the lead apron protection. • Badges are analyzed on a monthly basis and allow for monitoring of cumulative radiation exposure. • Current occupational exposure recommendations set the upper effective dose equivalent of 50 mSv/y (5 rem/y) and a cumulative dose not to exceed 10 mSv (1 rem) times the age of the worker. Thus, lifetime exposure for a year-old radiation worker would be mSv (50 rem). Modern x-rays are completed within milliseconds, and typical radiation exposure is a small fraction of what it was years ago; however, prolonged patient exposures to x-rays may occur as increasingly complex procedures are performed using continuous fluoroscopy. More than 50 reports of patient injury from prolonged exposure to x-rays during fluoroscopic procedures occurred in alone, resulting in the health advisory issued by the Food and Drug Administration.1 • Several reports of serious patient injuries from radiation during fluoroscopy have been recently published.3,4 • Recognition of patient injury from fluoroscopy is often delayed, since the effects of excessive radiation exposure are usually not immediately apparent. • Fluoroscopy injuries documented in the past 20 years have included skin burns serious enough to require skin grafting. • Since reporting of fluoroscopy injury is not mandatory, the actual extent of this problem is unknown. Occupational radiation exposure can be reduced to as low as is reasonably achievable through adherence to 3 basic principles: • Reduce exposure time. • Increase the distance from the radiation source.

• Shield yourself and your patient from direct and scattered radiation. The longer one is exposed to a radiation field, the greater the total radiation dose. Thus, limiting time of exposure is a simple, common-sense method for reducing risk. • With modern fluoroscopic systems, a short burst of radiation used with “last image hold” capability allows the operator to identify needle position with minimal x-ray exposure time. • This technique allows the interventionalist to take a fluoroscopic “snapshot” of the field, hold the static image on the monitor, move the needle a small distance toward the target, and then obtain another brief fluoroscopic image to determine the next needle position. • A recent study found the average time required for needle placement during various interventional pain procedures was seconds, which is quite low compared to other dosimetry-measured radiation exposure times in other medical specialties using fluoroscopy.5 Based on the inverse square law, the amount of radiation exposure is proportional to the inverse square of the distance from the source. • Therefore, the amount of radiation exposure declines exponentially as the operator moves away from the source. • With fluoroscopy, distances of 6 ft or more from the x-ray tube, and from scatter radiation coming off the patient and table, result in minimal radiation exposure. Lead aprons are mandatory, and thyroid shields are recommended, as standard garb within the procedure room during fluoroscopy (Figure ). • Lead shielding can be tailored to body contours and made reasonably comfortable while providing an effective barrier to radiation exposure especially to the thyroid and pelvis. • A wide variety of lead glass screens can be placed between the operator and the x-ray source and/or patient in order to reduce direct and scatter radiation exposure, respectively. • The interventional procedure room can be configured with leaded glass screens that are attached to ceiling mounts or used with rolling frames on the floor to fit a particular space. • Leaded glass lenses offer an effective barrier to eye exposure and can be configured with optical correction; however, they may be heavy and uncomfortable. Regular glass lenses also afford some protection and other alternative materials for eye protection are becoming available (Figure ).

Figure Radiation protection with lead apron, glasses, and screen. Some experts have advocated the use of leaded gloves in order to reduce hand exposure to x-rays during fluoroscopic procedures. • With lead gloves, there is less chance of hand exposure to scattered x-rays. • However, the increased density of lead gloves placed within the x-ray field will cause the fluoroscope to increase output as it tries to penetrate the high-density lead. • Therefore, leaded gloves within the field of view of the monitor will cause an automatic increase in direct and scattered radiation. • Lead gloves are also expensive and may decrease the tactile sensation, hindering safe and accurate needle placement. • Keeping hands completely out of the beam is advisable with or without lead gloves.

SUMMARY The fluoroscope has revolutionized the treatment of chronic pain. For optimal safe and effective use, the

pain specialist physician should have an in-depth understanding of fluoroscopy and the fluoroscope to accurately diagnose and treat the physical generators of pain. Skill with the fluoroscope combined with needle placement skills and an understanding of the anatomy and pathophysiology of chronic pain will allow the interventional pain specialist to help patients with chronic pain more effectively than ever before possible.

References FDA Public Health Advisory. Avoidance of serious x-ray induced skin injuries to patients during fluoroscopically guided procedures. Rockville, MD: Food and Drug Administration, September 9, Wong L, Rehm J. Radiation injury from a fluoroscopic procedure. N Engl J Med. ;e Sovik E, Klow NE, Hellesnes J, Lykke J. Radiation-induced skin injury after percutaneous transluminal coronary angioplasty: case report. Acta Radiol. ; Knautz MA, Abele DC, Reynolds TL. Radiodermatitis after transjugular intrahepatic portosystemic shunt. South Med J. ; Manchikanti L, Cash KA, Moss TL, Pampati V. Radiation exposure to the physician in interventional pain management. Pain Physician. ;

CHAPTER 2

Computed Tomography Guidance in Pain Management Ronil V. Chandra, Thabele-Leslie Mazwi, Daniel Oh, Albert J. Yoo, and Joshua A. Hirsch

INTRODUCTION • Computed tomography (CT) creates an image of the body by reconstructing image slices from a series of x-ray projections acquired as the patient is moved through the center of the CT scanner. The CT scanner is able to measure the attenuation of the x-ray beam by the various tissues along each projection. The spatial localization of these tissues is then determined using mathematical algorithms. • The CT image is then displayed as a matrix of x-ray attenuation values using a reference scale (Hounsfield units [HU]) relative to water; water is assigned a value of 0 HU on all scanners. On this scale, air measures approximately − HU and dense cortical bone approximately + HU. • A CT image can be displayed as different shades of grey by appropriately choosing the display parameters. • All current CT scanners offer multi-detector technology (multiple CT slices can be obtained in one rotation of the gantry) and enable isotropic acquisition (ie, spatial resolution is equal in x, y, and z planes) with volumetric multi-planar image reconstruction.

ADVANTAGES OF CT GUIDANCE FOR INTERVENTIONAL PROCEDURES Anatomical Detail • Soft tissue structures such as nerve roots and bony constraints including severe scoliosis or large osteophytes are accurately defined (Figure ). Particularly useful for nerve root or epidural injections in patients with advanced degenerative disease or previous surgery. • Important neurovascular structures are visualized in real time (eg, avoidance of the vertebral artery in cervical nerve root blocks). • Allows precise needle localization for very small targets.

• Avoids inadvertent transgression of nontarget tissue compartments (Figure ).

Figure CT-guided facet joint injection. (A) Axial prone CT clearly identifies large facet joint osteophytes (arrow) that would make intra-articular needle position difficult to achieve under fluoroscopic guidance. (B) CT guidance facilitates accurate targeting of the narrowed articular space, and intra-articular position (arrow) is achieved.

Figure CT-guided acetabuloplasty for metastasis. (A) Axial CT clearly identifies soft tissue mass (black arrow) in anterior column of acetabulum, with narrow needle window (dotted line) between common femoral vessels (red arrow) and intra-abdominal compartment (star). (B) CT guidance allows accurate needle placement without injury to neurovascular bundle nor transgression of nontarget compartments. (C) In spite of the focal areas of cortical breach in the acetabular cortex (black arrow), careful injection of Polymethylmethacrylate (PMMA; red arrow) under CT guidance allows delivery without intra-articular extravasation.

Needle Placement • Unlike fluoroscopy, which is hindered by tissue overlap, multi-planar reformats allow three dimensional trajectory planning. • Direct visualization allows accurate needle placement with respect to the target nervous structure without use of contrast media. • If required, the expected spread of injectate can be determined by injection of a small amount of contrast media (Figure ). This is useful for epidural injections where inadvertent intrathecal needle tip position is clearly recognized by injection of contrast media.1

Figure CT-guided celiac plexus blockade. Axial prone CT clearly identifies needle position adjacent to the aorta during bilateral transcrural approach. Injection of a small amount of contrast reveals expected spread of final injectate.

DISADVANTAGES OF CT GUIDANCE • Generally more time consuming than fluoroscopic approach. • May have greater radiation dose to patient and practitioner compared to fluoroscopy depending on techniques used. • Requires further expertise—an understanding of CT imaging, normal CT anatomy, and pathology. • Less accessible modality, typically located in radiology departments. • Requires further trained personnel—CT technologists.

PREOPERATIVE CONSIDERATIONS • Patient positioning For ideal needle trajectory The simplest needle trajectory to achieve accurately is perpendicular to the floor—take advantage of oblique prone positioning if possible (Figure ). Ideally, the entire needle trajectory should lie in one axial CT image—this can be facilitated by angling the CT machine gantry (Figures and ). Note that positioning in the lateral decubitus or oblique prone position alters the position of the diaphragm, which can facilitate retroperitoneal needle access without transgressing the pleural space.

Figure Oblique prone positioning to facilitate easier needle placement during acetabuloplasty. (A) Axial prone CT during planning reveals lucent mass in the posterior column of the acetabulum. With prone positioning, an oblique needle trajectory (dotted line) is required. (B) With oblique prone imaging a needle trajectory perpendicular to the floor (dotted line) is obtained, which is easier and less time consuming to achieve. (C) Imaging with gauge needle in place, prior to cortical entry. (D) Postprocedure CT after PMMA injection (red arrow) and removal of needle, with no leakage into the hip joint (black arrow).

Figure The angled gantry approach. (A) The traditional CT gantry position is perpendicular to the CT table. (B) Angling the CT gantry along the line of an angled needle trajectory allows the entire needle trajectory to remain along a single CT slice.

Figure CT-guided pelvic collection drainage using angled gantry approach. (A) Axial CT clearly identifies pelvic collection (dotted lines) but without clear needle access. (B) Tilting the CT gantry and repeat imaging identify a safe angled direct needle trajectory. (C) Pigtail drain tube successfully placed into pelvic collection. To maximize patient comfort Maximizing patient comfort prior to commencing the procedure minimizes patient motion during needle placement. The prone position is well tolerated with pillows under the chest, hips, and ankles. Further pillows, wedges, or towels may be necessary to achieve a comfortable oblique prone position. • Needle entry planning Once the patient is positioned, a skin grid marker is placed over the target entry site. An initial radiographic CT scout image is acquired to delineate the superior and inferior extent of the planning CT scan. An initial planning CT scan is performed to define the needle entry site, using the skin grid markers (Figure ). The trajectory is planned, taking into account anatomical limitations. The needle entry site is marked on the patient’s skin, the skin grid is removed, the site is prepped with antiseptic solution, and the patient is draped appropriately. If available, a monitor in the CT room should have the needle trajectory available as a reference image to facilitate needle placement.

Figure Use of skin grid to mark skin entry position. (A) Photograph of patient positioned prone oblique on CT table, with skin grid placed (arrow), and laser light used to mark entry position. (B) Corresponding CT image with skin grid markers (arrow) to guide needle trajectory into acetabular mass (star).

INTRAOPERATIVE TECHNICAL STEPS • Local anesthetic is injected at the skin entry marker site. • It may be helpful to leave the local anesthetic needle in place along the planned needle trajectory for subsequent confirmation by CT scanning. • Infiltrate local anesthetic along the planned needle trajectory. A 22G spinal needle can be used to infiltrate deeply and into the periosteum if entering a bony target. • As the definitive needle is placed, the needle position and trajectory should be verified with intermittent CT imaging. Intermittent CT imaging needs to define the entire needle course and needle tip. The needle tip can be verified by the identification of the bevel on the needle tip or the presence of a black shadowing artifact. Ensure adjacent CT images above and below are reviewed (Figures 28 and ).

If using an angled approach in the superior-inferior direction, more frequent CT imaging is recommended.

Figure Demonstration of needle tip. (A) Axial CT during localization of local anesthetic needle reveals shadowing artifact arising from the tip, confirming identification of the needle tip. (B) With placement of the larger gauge needle, a larger shadowing should be expected. The identification of the bevel of the needle tip is the most accurate method to localize the needle tip.

Figure Demonstration of needle tip during sacroplasty. (A) Axial CT during localization reveals minor shadowing artifact arising from near the tip, however less than expected for a gauge needle. (B) Imaging mm cranial identifies further shadowing artifact as well as the diamond tip bevel confirming exact needle tip position. • Once the target location is reached, diluted contrast media can be injected to assess intended spread of planned injectate. • Final postprocedure CT should be performed after needle is removed. • Use of CT fluoroscopy. CT fluoroscopy is a technique in which the operator remains in the CT room while imaging is acquired, displayed on a monitor, and then used to guide needle placement. Requires additional hardware and software—a display monitor in the CT room, a foot pedal to initiate scanning and control console to initiate table movement (Figure ). Best used when the entire needle trajectory lies in one axial slice and minimal needle manipulations are expected. Deviation from the needle trajectory often requires multiple images to be acquired to achieve correction. Due to radiation exposure, the operator must wear a lead apron and thyroid shield. Lead eye protection is recommended. The typical radiation dose rate in CT fluoroscopy is approximately 7 times lower than the dose rate with conventional diagnostic CT parameters, but it can be up to 60 times higher than conventional fluoroscopy depending on dose settings.2

Figure Photograph of patient draped and positioned in preparation for CT fluoroscopy, with inroom monitor, controlling joystick (black arrow) and foot pedal (white arrow). This can lead to large radiation doses to patient and operator if not used appropriately. Furthermore, radiation dose is concentrated on a focal area of skin and can result in a large skin radiation dose for the patient. However, when used appropriately (low tube current and minimal exposure time), it can result in reduced patient radiation dose and reduced procedural time compared to conventional CT guidance.3 For selected procedures such as epidural injections and lumbar nerve root blocks, this method can result in radiation dose levels and procedural times similar to conventional fluoroscopic

guidance.1,4 There are two modes of CT fluoroscopic imaging: Quick check imaging • The operator presses a pedal to acquire CT images. • Typically 3 images are displayed on a screen, with a central image at the expected needle location, and an image above and below. • Lower patient and operator radiation dose than continuous imaging.2 Continuous imaging • CT scanner can acquire continuous imaging (~10 frames per second) during needle manipulation to reproduce live nature of imaging with conventional fluoroscopy. • Requires nonmetallic needle holders to ensure that operator’s hands are not in gantry. This is less tactile method for needle placement. • Results in a high patient skin and operator radiation dose. • If using this mode, there should be an inbuilt preset time limit for CT exposure to avoid excessive radiation dose. • May be of benefit in targets within particularly mobile organs such as the lung or liver.

CLINICAL PEARLS • Prior to any case, review the mechanics of the CT gantry, and ensure that all necessary equipment is available. • For obese patients, ensure the patient is within the maximal CT table weight restrictions and can fit in to the CT gantry. • If possible, once needle trajectory is planned and local anesthetic is infiltrated, manipulate the needle during the remainder of the procedure while the patient remains in the CT gantry—this reduces the chance of patient motion with table movement, and reduces procedure time. • Use the laser guiding light in the CT gantry as frequently as possible. If the laser light bisects the needle hub, the needle trajectory will be in the plane of the CT image. If the needle hub lies above the plane of the laser guiding light, the needle tip is pointing in the opposite direction and can be adjusted without repeat imaging. • If the patient needs to be moved into and out of the CT gantry, use of a pedal or sterile cover over the CT controls can allow the operator to move the CT table immediately and independently of the CT technician. • If there is no safe direct access to the target in the axial plane, consider tilting the CT gantry to obtain oblique axial imaging—this may facilitate a safe angled pathway in which the entire needle trajectory can be visualized. • Injection of normal saline or 5% dextrose can allow creation of a needle trajectory pathway in between compartments, eg, facilitating access to the celiac plexus by enlarging the retroperitoneal space or displacing adjacent tissues. • If there is a CT contrast allergy, depending on the target location, a small amount of air can be effectively used as a contrast medium, eg, in confirming epidural needle tip position.1

• Radiation reduction. Any reduction in radiation to the patient also reduces radiation dose to the operator and to assisting staff members. Acquire images only when necessary to assess needle position and trajectory. Step as far away from the CT gantry during image acquisition as possible. Exit the room if not using CT fluoroscopy. If using CT fluoroscopy. Use the quick check method. A lower tube current during imaging can reduce radiation dose while providing adequate trajectory information without loss of anatomical resolution.2 Place the foot pedal further away from the gantry to reduce dose (radiation intensity is inversely proportional to the square of the distance from the source).4 A lead drape over the patient adjacent to the scan plane can reduce scattered dose to the operator’s hands.5

Suggested Reading Carlson SK, Bender CE, Classic KL, et al. Benefits and safety of CT fluoroscopy in interventional radiologic procedures. Radiology. ; Joemai RM, Zweers D, Obermann WR, Geleijns J. Assessment of patient and occupational dose in established and new applications of MDCT fluoroscopy. AJR Am J Roentgenol. ; Paulson EK, Sheafor DH, Enterline DS, McAdams HP, Yoshizumi TT. CT fluoroscopy-guided interventional procedures: techniques and radiation dose to radiologists. Radiology. ; Wagner AL. Selective lumbar nerve root blocks with CT fluoroscopic guidance: technique, results, procedure time, and radiation dose. AJNR Am J Neuroradiol. ;

References 1. Wagner AL. CT fluoroscopy-guided epidural injections: technique and results. AJNR Am J Neuroradiol. ; 2. Paulson EK, Sheafor DH, Enterline DS, et al. CT fluoroscopy-guided interventional procedures: techniques and radiation dose to radiologists. Radiology. ; 3. Carlson SK, Bender CE, Classic KL, et al. Benefits and safety of CT fluoroscopy in interventional radiologic procedures. Radiology. ; 4. Wagner AL. Selective lumbar nerve root blocks with CT fluoroscopic guidance: technique, results, procedure time, and radiation dose. AJNR Am J Neuroradiol. ; 5. Nawfel RD, Judy PF, Silverman SG, Hooton S, Tuncali K, Adams DF. Patient and personnel exposure during CT fluoroscopy-guided interventional procedures. Radiology. ;

CHAPTER 3

Ultrasound Guidance for Interventional Pain Management Hariharan Shankar and Kanishka Rajput

INTRODUCTION Lazzaro Spallanzani is credited with the initial discovery of ultrasound (US) navigation by bats in But it was Pierre Curie’s invention of the US-generating piezoelectric crystal that heralded further development of US technology. Following its utilization in medical imaging and guidance, US imaging has seen tremendous progress in its applications and technology in the last 5 decades. Recent years have seen a surge in the use of US for diagnosis and therapeutic interventions in regional anesthesia. US is now making progress in the field of pain medicine because of its utility both in the diagnosis of several nerve, muscle, and joint pathologies and for the ability to see the target and the needle for injection of therapeutic substances (Table ). TABLE Advantages of Ultrasound Guidance • Watch real time injectate spread • Avoid structures, eg, pleura • Decrease injectate volume • Lack of radiation • May avoid multiple passes • Detect pathology in the target area • Avoid painful muscle contractions 2° to stimulation • Good educational tool on clinical anatomy Following its initial use in regional anesthesia, US was quickly adopted for a variety of pain medicine interventions (Table ). Many feasibility studies have been published that attest to its safety and convenience. Studies have also documented elimination of radiation exposure secondary to the use of US imaging for pain medicine interventions.

TABLE List of Common Procedures Performed in Pain Medicine Where US Guidance is Utilized • Musculoskeletal Joint injections Bursa injections Trigger point injections Piriformis injections Tendon injections Plantar fasciitis injections • Neuraxial Preprocedural scanning Caudal epidural Facet and medial branch injections Spinal root injections • Sympathetic blocks Stellate ganglion block Celiac plexus block Hypogastric plexus block Ganglion impar • Peripheral nerve injections

BASIC PHYSICS OF ULTRASOUND • Sound waves at frequencies greater than 20 kHz are called US. • Medical US uses frequencies in the range of 2 to 20 MHz. • When an electrical current is passed through piezoelectric crystals, they vibrate and produce ultrasound waves. • The US waves travel through tissues at a velocity that depends on the tissue with an average velocity of m/s assumed for all biologic tissues. • This velocity is utilized to calculate the depth (the time from pulse generation to detection times half the velocity). • The distance from one crest of the waveform to the next is the wavelength.

Attenuation • As the waves travel through tissues, there is a loss in intensity or attenuation. This is due to the waveinduced motion of the tissues, absorption, reflection, and scattering. Attenuation is directly proportional to the frequency and the length of the path. This is described in decibels per centimeter of tissue traversed per megahertz, and they range from to dB/cm/MHz for most tissues. Attenuation results in conversion of the mechanical energy of the waveform into thermal and nonthermal energy.

Acoustic Impedance • Acoustic impedance between tissues, which is density times the average velocity, determines the amount of reflection. Increasing impedance difference increases the intensity of reflection with no echoes occurring with identical impedances. Impedance matching between the transducers and skin is improved by applying a liberal amount of a water-soluble gel. In addition, the face of the transducer is coated with a quarter-wave matching layer to decrease the impedance difference.

PRINCIPLES OF ULTRASOUND • Modern US transducers have arrays of piezoelectric crystals, which are electrically excited in small successive groups to create a sweeping effect of the beam. • The transducers serve the dual function of generating and receiving signals reflected back from the tissues. • US used in medical imaging is delivered in pulses and uses a brightness mode for display. • The image is then displayed on the screen in shades from black to white. • When the waves are completely reflected by a tissue structure they appear white or hyperechoic, and when none is reflected, they appear black or anechoic on the display. Bone and fascia are hyperechoic, while blood vessels are anechoic. • Nerves and muscles have hyperechoic structures in a bed of hypoechogenicity to anechogenicity creating a stippled or starry sky appearance. • Only a small percentage of the waves are returned back to the transducer, with the majority either travelling further into the tissues or scattered because of refraction. • The US waves move through tissues and create rarefaction and compression. Two distinct patterns of reflection give rise to the echoes that make up an US image—specular reflection and scattering. 1. Specular reflection. It is responsible for the bright appearance of fibrous structures such as tendons. 2. Scattering. It gives rise to the characteristic texture (echo texture) of the image seen within soft tissue in a manner that loosely resembles the waves created by a pebble dropped into a pond. The ultrasonic beam in modern machines scans the tissues by electronic control such that each element is excited with a time delay, creating a sweeping motion for the image. Beam focusing is achieved by the design of the transducer: lenses placed in the front of the transducer or with the use of phased array.

THE PORTABLE ULTRASOUND MACHINE The modern portable US machine has made it easy to perform bedside evaluations and interventions. The transducers, the most critical components of the US machine, contain the piezoelectric crystals and are responsible for the transmission and receiving of the US waves. The electronic circuitry of the central processing unit and the image display screen form the other major components. The image system has user interfaces including a computer keyboard to enter information and buttons, knobs, and sliders to control the various operations (Figure ). Some newer machines have touch screen capabilities for adjusting the various parameters.

Figure (A) and (B) Key pads and other control knobs of two portable ultrasound machines.

Transducers • Transducers are manufactured in many different shapes and sizes. • The commonly used transducers in pain medicine are the linear array and curved array transducers (Figure ). • The frequencies used for medical imaging are generally in the range of 1 to 18 MHz. • Transducers have different frequency ranges to provide versatility in imaging at different depths and are centered around their resonant frequency. • Based on the location of the target, a suitable frequency range transducer is selected. • The lower-frequency transducers are optimal for viewing deeper structures, and the higher frequencies are used for more superficial structures. • The choice of frequency is a trade-off between spatial resolution of the image and imaging depth: the deeper the penetration, the less the resolution. • The frequency of the selected transducer may be further adjusted using a dial.

Figure Transducers used in pain medicine interventions. (A) Curved array transducer producing lower ultrasound frequencies for use in imaging deeper structures. (B) Linear array transducer for use with superficial structures. (C) Phased array transducer for use with deeper structures and abdomen. (D) “Hockey stick” transducer for use with superficial structures and the small foot print facilitates use in narrow areas.

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Approach to Pain Medicine Care - Brigham and Women’s Hospital

Atlas of interventional pain management 4th edition free download