aospine masters series volume 1 metastatic spinal tumors

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  • AOSpine Masters SeriesMetastatic Spinal Tumors

  • AOSpine Masters SeriesMetastatic Spinal Tumors

    Series Editor:Luiz Roberto Vialle, MD, PhDProfessor of Orthopedics, School of MedicineCatholic University of Parana StateSpine UnitCuritiba, Brazil

    Guest Editors:Ziya L. Gokaslan, MD, FACSDonlin M. Long ProfessorProfessor of Neurosurgery, Oncology, and Orthopaedic SurgeryDirector, Neurosurgical Spine ProgramVice Chair, Department of NeurosurgeryJohns Hopkins University School of MedicineBaltimore, Maryland

    Charles G. Fisher, MD, MHSc, FRCSCProfessor and HeadDivision of Spine SurgeryDepartment of Orthopaedic SurgeryUniversity of British ColumbiaVancouver, British Columbia

    Stefano Boriani, MDUnit of Oncologic and Degenerative Spine Surgery Rizzoli Orthopedic Institute Bologna, Italy

    Thiem eNew York Stut tgar t Delhi Rio

    978-1-62623-048-4c0FM.indd 3 7/2/14 1:15 PM

  • Thiem e Medical Publishers, Inc.333 Seventh Ave.New York, NY 10001

    Execut ive Editor: Kay ConerlyManaging Editor: Judith Tom atEditor ial Assistant: Haley PaskalidesSenior Vice President , Editorial and Elect ronic Product Developm ent: Cornelia SchulzeProduct ion Editor: Barbara A. ChernowInternat ional Product ion Director: Andreas Schaber tIn ternat ional Market ing Director: Fiona HendersonDirector of Sales, North Am erica: Mike Rosem anInternat ional Sales Director: Louisa TurrellVice President , Finance and Accounts: Sarah VanderbiltPresident: Brian D. ScanlanCom positor: Carol Pierson, Chernow Editorial Services, Inc.

    Library of Congress data is available from the publisher.

    Copyright 2015 by Thiem e Medical Publishers, Inc.

    Im portant note: Medicine is an ever-changing science undergoing cont inual developm ent . Research and clin ical experience are cont inually expanding our knowledge, in par t icular our knowledge of proper t reatm ent and drug therapy. Insofar as th is book m ent ions any dosage or applicat ion , readers m ay rest assured that the authors, editors, and publishers have m ade every e or t to ensure that such references are in accordance w ith the state of know ledge at the tim e of production of the book. Never theless, th is does not involve, imply, or express any guarantee or responsibilit y on the par t of the publishers in respect to any dosage inst ruct ions and form s of applicat ions stated in the book. Every user is requested to exam ine carefully the m anufacturers lea ets accom panying each drug and to check, if necessary in consultat ion w ith a physician or specialist , w hether the dosage schedules m ent ioned therein or the contraindicat ions stated by the m anufacturers di er from the statem ents m ade in the present book. Such exam inat ion is part icularly im portant w ith drugs that are either rarely used or have been newly released on the m arket . Every dosage schedule or every form of applicat ion used is ent irely at the users ow n r isk and responsibilit y. The authors and publishers request every user to repor t to the publishers any discrepancies or inaccuracies not iced. If errors in th iswork are found after publicat ion , errata w ill be posted at w w w.thiem e.com on the product descript ion page. Som e of the product nam es, patents, and registered designs referred to in th is book are in fact registered t radem arks or proprietary nam es even though speci c reference to th is fact is not always m ade in the text . Therefore, the appearance of a nam e w ithout designat ion as proprietary is not to be const rued as a representat ion by the publisher that it is in the public dom ain .

    Prin ted in China by Everbest Prin t ing Ltd.5 4 3 2 1ISBN 978-1-62623-046-0

    Also available as an e-book:eISBN 978-1-62623-048-4

  • Volum e 1 Metastat ic Spinal Tum ors

    Volum e 2 Prim ary Spinal Tum ors

    Volum e 3 Cervical Degenerat ive Condit ions

    Volum e 4 Adult Spinal Deform it ies

    Volum e 5 Spinal Traum a 1, Cervical

    Volum e 6 Spinal Traum a 2, Pitfalls on Thoracolum bar

    Volum e 7 SCI and Regenerat ion

    Volum e 8 Back Pain

    Volum e 9 Pediat r ic Spinal Deform it ies

    Volum e 10 Spinal Infect ion

    AOSpine Masters SeriesLuiz Roberto Vialle, MDSeries Editor

  • Forew ord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ixJe rey C. Wang

    Series Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiLuiz Roberto Vialle

    Guest Editors Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiiiCharles G. Fisher, Stefano Boriani, and Ziya L. Gokaslan

    1 Evaluat ion and Decision Making for Metastat ic Spinal Tum ors . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Yan Michael Li, Michael S. Dirks, Claudio E. Tatsui, and Laurence D. Rhines

    2 Neoplast ic Spinal Instabilit y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Daryl R. Fourney and Charles G. Fisher

    3 Major Com plicat ions Associated w ith Stereotact ic Ablat ive Radiotherapy for Spinal Metastasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Sim on S. Lo, Arjun Sahgal, and Eric L. Chang

    4 En Bloc Resect ion in the Treatm ent of Spinal Metastases: Technique and Indicat ions . . . . . . 34Ilya Laufer, Jean-Paul Wolinksy, and Mark H. Bilsky

    5 Region-Speci c Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Ioan Adrian Lina, Patricia L. Zadnik , and Daniel M. Sciubba

    6 Spinal Reconst ruct ion and Fixat ion/Fusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Rajiv Saigal and Dean Chou

    7 Minim ally Invasive Surgery for Metastat ic Spine Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Meic H. Schm idt

    8 Vertebral Augm entat ion for Metastat ic Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Ehud Mendel, Eric C. Bourekas, and Paul Porensky

    9 Surgical Com plicat ions and Their Avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Michelle J. Clarke

    Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

    Contents

  • With the large num ber of publicat ions, journals, and textbooks available to the spine pract i-t ioner, it is refresh ing to see a novel publicat ion in a new form at that has a speci c focus on relevant and im portant contem porary topics. With the in t roduct ion of the AOSpine Masters Series and the rst volum e focused on m eta-stat ic spinal tum ors, new ground is broken on an innovat ive collect ion of educat ional m ate-rial from the worlds experts in the spine sur-gery eld.

    I congratulate all the editors and the authors of AOSpine Masters Ser ies and the inaugu ral volum e for their unique vision in creat ing th is series that collects the vast knowledge of the top experts in the eld. The AOSpine Masters Series addresses current topics, target ing not only our large spine surgeon m em bership, but also spine pract it ioners on a global basis. It is not a journal or a convent ional book, but a publicat ion for the worlds experts to share their personal views and recom m endat ions on a given topic. The goal of th is series is to con-t r ibu te to an evolving, dynam ic m odel of an evidence-based m edicine approach to spine care. Not only is the inform at ion contained in th is series and in the rst volum e new, but the pre-sentat ion of the m aterial is t ru ly revolut ionary. The process involves a synthesis of best avail-able evidence and consensus expert opinions to arrive at appropriate recom m endat ions for pat ient care. There is no other source that com -bines th is inform at ion or presents it in such a

    form at for spine surgeons to approach the dis-eases of the spine. The foundat ion for t reat-m ents of the disease process is presented, w ith clinical pearls and complications avoidance, and an update on the current literature and key ar-t icles. I am especially excited for young spine surgeons and for residents and fellows in t rain-ing program s, because this textbook w ill enable them to learn about spine surgery in a unique way that w ill provide them w ith a bet ter under-standing of the current status of our knowledge of the spine.

    The authors are all knowledgeable experts w ho are world-renow ned in their eld . The editors w ho have created th is vision should be congratu lated and very proud of th is very im -pressive collect ion of exper t s and the un ique m ethod of p resen tat ion . The en t iret y of the chapters com e together to form an educational t reatm ent focus on the individual topics. The ent ire collect ion form s an am azing series of t ruly m asters level in form at ion that is unpar-alleled. I am very excited by the AOSpine Mas-ters Series and look forward to future volum es.

    Jef rey C. Wang, MDChairm an, AOSpine In ternat ionalChief, Orthopaedic Spine Service

    Co-Director USC Spine CenterProfessor of Orthopaedic Surgery and

    NeurosurgeryUSC Spine Center

    Los Angeles, Californ ia

    Foreword

    978-1-62623-048-4c0FM.indd 9 7/2/14 1:15 PM

  • Spine care is advancing at a rapid pace. The challenge for todays sp ine care professional is to qu ickly syn thesize the best available evi-dence and expert opinion in the m anagem ent of sp ine pathologies. The AOSpine Masters Series provides just thateach volum e in the series delivers pathology-focused expert opin-ion on procedures, diagnosis, clin ical w isdom , and pitfalls, and highlights todays top research papers.

    To bring the value of its m asters level edu-cat ional courses and academ ic congresses to a w ider audience, AOSpine has assem bled in ter-nat ionally recognized spine pathology leaders to develop volum es in th is Masters Series as a

    vehicle for sharing their experiences and exper-t ise and providing links to the literature. Each volum e focuses on a current com pelling and som et im es controversial topic in spine care.

    The un ique and e cien t form at of the Masters Ser ies volum es quickly focuses the at ten t ion of the reader on the core in form a-t ion crit ical to understanding the topic, w hile encouraging the reader to look fur ther in to the recom m ended literature.

    Through th is approach , AOSpine is advanc-ing spine care worldw ide.

    Luiz Roberto Vialle, MD, PhD

    Series Preface

  • To pract ice evidence-based spine surgery, a spine surgeon m ust com bine a rigorous and cr it ical approach to the evaluat ion of the sci-en t i c literature w ith clin ical exper t ise and a st rong com m itm ent to pat ien t cen teredness and hum anist ic values. Pat ients w ith m eta-stat ic disease of the spine are a very unique pat ient ent it y for spine surgeons or any care providers; these pat ien ts are dying, and their qualit y of life for their rem aining t im e is a very precious and personal process. Shared decision m aking in the care of these pat ients is essen-t ial, and often these decisions are agonizing as the physician st r ives to do the best , w ithout doing too m uch . From palliat ive or hospice care to m ajor surgery, the goal of th is book is to provide guidance for clin icians to m ake the right decisions and direct the best level of care possible for m etastat ic spine pat ients.

    In m etastat ic spine disease, technologic ad-vancem ents and high-quality literature on neu-rologic recovery, cost-e ect iveness, stabilit y, and health-related qualit y of life (HRQOL) have st rengthened surgerys role in its m anage-m ent; however, choosing the correct t reatm ent rem ains a challenge. Sim ilarly on the oncology side, new radiat ion technologies, such as ste-reotact ic radiosurgery have changed the t reat-m ent paradigm ; form ally radioresistant tum ors are now radiosensit ive, negat ing the need for h igh-r isk surgical p rocedures. New, targeted m olecular drugs are allow ing m etastat ic pa-

    t ients to live longer, thus changing t radit ional decision aids for m etastat ic spine pat ients, es-pecially for lung and renal cancer pat ients. Or-gan izing and understanding all of these new concepts and technologies from a decision - m aking perspect ive is one of the m ajor goals of th is book.

    The chapters have been researched and w rit-ten by key opinion leaders in spine oncology and range from evaluat ion and decision-m aking principles to a spect rum of nonoperat ive and operat ive t reatm ent options that hich have been evolving at a rapid pace, especially over the last decade. The th ree guest editors have reviewed each chapter to ensure consistency and the necessary syn thesis of the best -available lit -erature and exper t opin ion . Fur therm ore, a conscious and very necessary e or t to ensure m ult idisciplinary appraisal and input has been taken . In fact , the input of the m edical and radiat ion oncologist s and radiology in terven-t ionalists, along w ith that of the spine surgeon, is em phasized th roughout th is book, just as it should be in the day-to-day care of sp ine m etastases patients. Mult iple authors were en-couraged for each chapter to ensure the m ost balanced, t ransparent , and comprehensive rep-resentat ion possible.

    Current ly, there is a t rue paradigm shift oc-curring in the m anagem ent of m etastat ic spine disease. Successful t reatm ent m ust accom plish pain palliat ion , preservat ion , or recovery of

    Guest Editors Preface

  • xiv Guest Editors Preface

    neurological funct ion and spine stabilit y. Fur-therm ore, w ith increased life expectancy, local control is gaining importance. The ult im ate goal in the t reatm ent of th is fragile pat ient popula-t ion is related to im provem ent in HRQOL, w hile lim it ing adverse even ts. We hope th is gu ide fram ed around best available literature, clin i-

    cal expert ise, and pat ien t preferences, w ill help ensure that th is goal is achieved as m anage-m ent cont inues to evolve at an excit ing pace.

    Charles G. Fisher, MD, MHSc, FRCSCStefano Boriani, MD

    Ziya L. Gokaslan, MD, FACS

  • Mark H. Bilsky, MDDepartm ent of NeurosurgeryMem orial Sloan-Ket tering Cancer Center New York, New York

    Stefano Boriani, MDUnit of Oncologic and Degenerat ive Spine

    Surgery Rizzoli Orthopedic Inst itute Bologna, Italy

    Eric C. Bourekas, MDAssociate Professor, Radiology, Neurology,

    and Neurological Surgery Chief of Neurosurgery, Departm ent of

    Radiology Wexner Medical Center Ohio State Universit y Colum bus, Ohio

    Eric L. Chang, MDProfessor and ChairDepartm ent of Radiat ion OncologyKeck School of Medicine of Universit y of

    Southern CaliforniaUniversit y of Southern California Norris

    Com prehensive CenterLAC+USC Medical CenterKeck HospitalLos Angeles, Californ ia

    Dean Chou, MDAssociate ProfessorDepartm ent of NeurosurgerySpine CenterUniversit y of CaliforniaSan FranciscoSan Francisco, California

    Michelle J. Clarke, MDAssistant Professor Departm ent of NeurosurgeryMayo Clin ic Rochester, Minnesota

    Michael S. Dirks, MDNeurosurgery ResidentWalter Reed Army Medical Center Washington, DC

    Charles G. Fisher, MD, MHSc, FRCSCProfessor and HeadDivision of Spine SurgeryDepartm ent of Orthopaedic SurgeryUniversit y of Brit ish Colum biaVancouver, Brit ish Colum bia

    Daryl R. Fourney, MD, FRCSC, FACSAssistant ProfessorDivision of NeurosurgeryRoyal Universit y HospitalUniversit y of SaskatchewanSaskatoon , Saskatchewan

    Contributors

  • xvi Contributors

    Ziya L. Gokaslan, MD, FACSDonlin M. Long ProfessorProfessor of Neurosurgery, Oncology,

    and Orthopaedic SurgeryDirector, Neurosurgical Spine ProgramVice Chair, Departm ent of NeurosurgeryJohns Hopkins Universit y School

    of MedicineBalt im ore, Maryland

    Ilya Laufer, MDDepartm ent of NeurosurgeryMem orial Sloan-Ket tering Cancer Center Departm ent of Neurological SurgeryWeill Cornell Medical CollegeNew York, New York

    Yan Michael Li, MD, PhDNeurosurgical Fellow and Sta M.D. Anderson Cancer CenterHouston, Texas

    Ioan Adrian Lina, MD Medical StudentUniversit y of Maryland School of

    MedicineDepartm ent of NeurosurgeryJohns Hopkins Universit y School

    of MedicineBalt im ore, Maryland

    Sim on S. Lo, MDAssociate Professor Departm ent of Radiat ion OncologyUniversit y Hospitals Seidm an

    Cancer CenterCase Com prehensive Cancer CenterCleveland, Ohio

    Ehud Mendel, MD, FACSTina Skestos Endowed Chair Professor, Neurosurgery, Oncology,

    Orthopedics, and In tegrated Spine Fellowship Program

    Vice Chair, Neurosurgery Clin ical A airs Wexner Medical CenterJam es Cancer CenterOhio State Universit y Colum bus, Ohio

    Paul Porensky, MDNeurosurgical ResidentWexner Medical Center Ohio State Universit y Departm ent of Neurological Surgery Colum bus, Ohio

    Laurence D. Rhines, MDProfessorDepartm ent of NeurosurgeryDivision of SurgeryUniversit y of Texas M.D. Anderson Cancer CenterHouston, Texas

    Arjun Sahgal, MDAssociate ProfessorUniversit y of TorontoDepartm ent of Radiat ion OncologySunnybrook Health Sciences Centre and the

    Princess Margaret Cancer CentreToronto, Ontario

    Rajiv Saigal, MD, PhDDepartm ent of Neurological SurgeryUniversit y of CaliforniaSan FranciscoSan Francisco, California

    Meic H. Schm idt, MD, MBA, FAANS, FACSProfessor of Neurosurgery and Vice Chair

    for Clin ical A airsRonald I. Apfelbaum Endowed Chair in

    Spine and NeurosurgeryDirector, Spinal Oncology Service,

    Huntsm an Cancer Inst itute Director, Neurosurgery Spine

    Fellowship Clin ical Neurosciences CenterUniversit y of Utah Salt Lake City, Utah

    Daniel M. Sciubba, MDAssociate Professor of Neurosurgery,

    Oncology & Orthopaedic SurgeryJohns Hopkins Universit yBalt im ore, Maryland

  • Contributors xvii

    Claudio E. Tatsui, MDAssistant ProfessorDepartm ent of NeurosurgeryDivision of SurgeryUniversit y of Texas M.D. Anderson Cancer CenterHouston, Texas

    Jef rey C. Wang, MDChairm an, AOSpine In ternat ional Chief, Orthopaedic Spine ServiceCo-Director USC Spine CenterProfessor of Orthopaedic Surgery and

    NeurosurgeryUSC Spine CenterLos Angeles, Californ ia

    Jean-Paul Wolinsky, MDAssociate ProfessorNeurosurgery and OncologyDepartm ent of NeurosurgeryJohns Hopkins Universit yBalt im ore, Maryland

    Patricia L. Zadnik, BA Spinal Oncology Research FellowSciubba LabJohns Hopkins Medicine Balt im ore, Maryland

  • Introduction

    Every year, m ore than 1.6 m illion new cases of cancer are diagnosed in the United States.1 Roughly half of these pat ients eventually die from their d isease, frequen t ly due to com plicat ions from m etastasis. The bone is the th ird m ost com m on site of m etastases follow ing lung and liver,2 and the spine is the m ost com m on site for bone m etastasis. As m any as 30 to 70% of cancer pat ien ts are found to have sp inal m etastases on autopsy studies.3 Sym ptom at ic secondary m etastases are est im ated to occur in approxim ately 10 to 20% of all cancer pat ients.3,4 The highest incidence of spinal m etastases is found in individuals 40 to 65 years of age, corresponding to the period of h ighest cancer r isk; 5 to 10% of pat ients w ith cancer develop spinal cord com pression.3 Up to 50% of spinal m etastases require som e form of t reatm ent , and 5 to 10% require surgical m anagem ent .5 Moreover, as survival rates for m any prim ary cancers continue to im prove, it is likely that the prevalence of spinal m etastases w ill increase.

    The com m on tum ors that spread to the spine in adults are breast , lung, prostate, renal, m elanom a, thyroid, and colorectal cancers, as well as hem atologic m alignancies.69 Mult iple myelom a has the h ighest tendency for spinal m etastases of all tum ors. Spine tum ors in children are represented by various form s of neuroblastom a and sarcom as.7 There are several ways in w hich tum ors dissem inate to the sp ine in

    cluding hem atogenous spread, direct extension or invasion, and seeding of the cerebrospinal uid. The thoracic spine is the m ost com m on site of involvem ent (70%), followed by the lum bar sp ine (20%), cervical sp ine, and sacrum . The vertebral body is involved in 80% of cases, w ith the posterior elem ents being a ected in 20%. Most m etastases are osteolyt ic (95%), w ith breast and prostate carcinom as account ing for m ost of the osteoblast ic m etastases. Occasionally both osteoblast ic and osteolyt ic m etastases occur in the sam e pat ient . Alm ost invariably, m etastat ic tum ors do not involve the dura (i.e., they are ep idural), bu t cer tain sarcom as and recurrent m etastat ic tum ors after radiotherapy can violate the dural barrier.

    With im provem ents in chem otherapy and horm onal therapy, and w ith the advent of novel targeted agents, m edical oncologists have an increased num ber of therapeut ic opt ions and survival t im es have im proved over the years. Radiotherapeut ic techniques have also evolved. Spinal stereotact ic radiosurgery and in tensit y m odulated radiat ion therapy (IMRT) techniques are enabling the delivery of h ighdose conform al radiat ion to spinal tum ors, erasing som e of the dist inct ion between radiosensit ive and radioresistant tum or h istologies. Last ly, advances in surgical techniques now enable the surgeon to treat spinal m etastases m ore e ect ively than before. Spine surgery can correct m echanical instabilit y, relieve neurologic com pression , and im prove pain .9,10 Increasingly, th is can be

    1Evaluation and Decision Making for Metastatic Spinal TumorsYan Michael Li, Michael S. Dirks, Claudio E. Tatsui, and Laurence D. Rhines

  • 2 Chapter 1

    ach ieved th rough m inim ally invasive techniques that entail less m orbidity and enable faster recovery.11,12

    The increasing num ber, and com plexity of, t reatm ent m odalit ies available for pat ients w ith spinal m etastases can com plicate the decision m aking, so the evaluat ion of these com plex patients m ust be m ult idisciplinary, and the decision to perform surgery m ust be based on four key aspects of the pat ients status: m edical t-ness, clin ical presentat ion , oncological status, and feasibilit y of surgical t reatm ent . This evaluat ion schem e is detailed in the rem ainder of th is chapter. It is not m eant to be an algorithm but rather a considerat ion of these four key aspects w hen developing a t reatm ent plan for the pat ient w ith spinal m etastasis and w hen determ ining the role of surgery.

    Medical Fitness

    The rst fundam ental considerat ion in m an-aging pat ien ts w ith m etastat ic sp inal d isease is their overall m edical condit ion . Many cancer pat ients have received prior chem otherapy or radiat ion , as well as steroids, and they m ay be m alnourished from their t reatm ent or from the disease. This m ay have an im pact on their abilit y to tolerate surgical in tervent ion.

    General patient factors such as overall health, nut r it ional status, and m edical com orbidit ies should all be considered in deciding w hether to recom m end surgery.10 Pat ient factors that have been found to be related to poor surgical outcom e include advanced age, obesit y, m alnutrit ion , diabetes, low bone m ineral density, chronic cor t icosteroid use, and bone m arrow suppression.13 Hem atologic status, such as leukopenia, throm bocytopenia, or coagulopathycondit ions com m on am ong cancer pat ien ts receiving chem otherapy or radiat ion therapym ust also be considered.

    As a general ru le, the m ore extensive the surgical procedure, the health ier the pat ien t needs to be in order to survive the surgery and enjoy durable bene ts. The pat ients m edical tness m ay be considered not only in deciding w hether to recom m end surgery or not , bu t also in the select ion of the appropriate surgical

    procedure and approach. Nonsurgical t reatm ents, such as convent ional radiat ion therapy or radiosurgery, or m in im ally invasive spinal procedures, such as percutaneous vertebral augm entation, m ay be appropriate for patients w ith signi cant m edical risks or lim ited prognosis.

    Clinical Presentation

    The second key considerat ion in the m anagem ent of m etastat ic spinal disease is the patients clin ical presentat ion . Pat ients w ith spinal m etastases typically present w ith neurologic symptom s, pain , or signs of m echanical instabilit y. It is im portant to recognize that the nature of the clin ical presentat ion and the severit y of the clin ical ndings have an im pact on the choice of t reatm ent m odalit y.

    Neurologic FunctionNeurologic dysfunct ion is a com m on nding in pat ients w ith m etastat ic disease of the spine. A careful neurologic assessm ent m ust look for sensory and m otor disturbance, autonom ic dysfunct ion, as well as long t ract signs. The m ain focus of the neurologic assessm ent is on localizing the poten t ial lesion and determ ining the clin ical exten t of the myelopathy or the functional radiculopathy. This clinical inform ation is then com bined w ith the radiological evaluation to assess the degree of epidural spinal cord com pression (ESCC) or nerve root com pression.

    Approxim ately 5 to 10% of pat ien ts w ith m etastat ic sp ine t um ors develop m etastat ic epidural spinal cord compression (MESCC). Historically, t reatm ent of MESCC by decompressive lam inectomy alone did not provide substant ial clin ical bene t beyond that of conven t ional radiat ion , and it frequent ly fur ther com prom ised sp inal stabilit y.14,15 The developm ent of im proved surgical approaches and spinal instrum entat ion to t reat instabilit y has resulted in bet ter surgical techniques for spinal decom pression and stabilizat ion.4 Using techniques of circum ferent ial decom pression and stabilizat ion, Patchell et al10 conducted a random ized prospect ive t r ial of 101 pat ients w ith MESCC. They conclusively showed that early surgical

  • Evaluation and Decision Making for Metastatic Spinal Tumors 3

    decom pression and stabilizat ion followed by postoperat ive radiotherapy is superior to t reatm ent w ith radiotherapy alone for pat ients w ith spinal cord com pression caused by m etastat ic cancer. It should be noted that th is study did not include pat ients w ith highly radiosensit ive/ chem osensit ive tum ors such as myelom a, lym phom a, and sm all cell lung cancer. Signi cant ly m ore pat ients in the surgery group (84%) than in the radiotherapy group (57%) could am bulate after t reatm ent (odds rat io [OR], 6.2; 95% con dence in terval [CI], 2.019.8; p = 0.001). These pat ients were able to m aintain their am bulat ion for a greater durat iona m edian of 122 days in the surgical group com pared w ith 13 days in the radiotherapy group (p = 0.003). The need for cor t icosteroids and opioid analgesics was signi cantly reduced in the surgical group.

    The degree of MESCC at the t im e of clin ical presen tat ion is h igh ly var iable am ongst pat ien ts. The select ion cr iter ia in the Patchell study included only pat ients w ith t rue deform at ion of the spinal cord. The Spine Oncology Study Group (SOSG) has developed and validated a sixpoint grading system to describe the degree of ESCC based on axial T2weighted m agnet ic resonance im aging (MRI) at the site of m ost severe compression (Fig. 1.1).16 This ra-diological assessm ent can be used in com bina

    tion w ith the neurologic exam ination and tum or h istology to help guide t reatm ent .

    For pat ients w ith h ighly radiosensit ive or chem osensit ive tum ors, nonsurgical t reatm ent m ay be adequate even in cases of h ighgrade spinal cord com pression due to the rapid response of these tum ors to radiat ion or chem otherapy. For other solid m etastat ic tum ors, the Patchell study suggests that h ighgrade (grade 2 or 3) MESCC is best t reated w ith surgical decom pression and stabilizat ion followed by radiat ion therapy. For pat ients w ho do not have signi cant myelopathy or funct ional radiculop-athy w ith lowgrade MESCC (grade 1c or less), surgery m ay not be necessary (unless there is signi cant spinal instabilit y; see below ). In th is case chem otherapeut ic or radiotherapeut ic opt ions (including spinal radiosurgery for radioresistant h istologies) can be ut ilized. The nature and severit y of the neurologic and radiological ndings clearly in uence the choice of t reatm ent .17

    PainMetastat ic spine tum ors m ost com m only com e to at tent ion w ith the developm ent of pain . This occurs in 83 to 95% of pat ients and typically precedes the developm ent of other neurologic sym ptom s.18 It is im portant to recognize that

    Fig. 1.1ac Schematic representation of the 6-point epidural spinal cord compression (ESCC) grading scale16. Grade 0, tumor is con ned to bone only. (a) Grade 1, tumor extension into the epidural space without deformation of the spinal cord. This is further divided into 1a, epidural impingement but no deformation of the thecal sac; 1b, deformation of the thecal sac without spinal cord abutment; and 1c, deformation of the thecal sac with spinal cord abutment but no compression. (b) Grade 2, spinal

    cord compression but cerebrospinal uid (CSF) is visible. (c) Grade 3, spinal cord compression without visible CSF. Grades 0, 1a, and 1b are considered for radiation as rst treatment in the lack of mechanical instability. Grades 2 and 3 de ne high-grade ESCC. Note: Used with permission from Bilsky MH, Laufer I, Fourney DR, et al. Reliabilit y analysis of the epidural spinal cord compression scale. J Neurosurg Spine 2010;13(3):324328.

  • 4 Chapter 1

    there are d i eren t t ypes of pain caused by m etastat ic spine tum ors, and the nature of the pain m ay im pact decision m aking. There are three t ypes of pain that a ect pat ients w ith sym ptom at ic spinal m etastases: local or biological, radicular, and m echanical.

    Local pain is thought to result from periosteal st retching, elevat ion of endosteal pressure, or in am m ation caused by tum or grow th.19 The pain can be localized, is often constant , and presen ts in the evenings and m ornings. It is described as a deep gnaw ing or aching pain at the site of disease; it does not worsen w ith m ovem ent and m ay improve w ith act ivity. This t ype of pain is quite responsive to ant i-in am -m atory or cor t icosteroid m edicat ions, and radiat ion therapy can relieve it by shrinking the tum or and decreasing the product ion of in am m atory m ediators.

    Radicular pain is caused by nerve root im pingem ent , w hich occurs w hen a spinal m etastases com presses the exit ing nerve root w ith in the spinal canal, w ith in the neuroforam en, or outside the foram en. The radicular pain follows a derm atom al dist r ibut ion and is described as sharp , shoot ing, or stabbing in nature. It is often constant and m ay or m ay not be relieved w ith changing posit ion . As w ith local pain , radicular pain m ay respond to therapies that can reduce the e ect ive size of the tum or, includ-ing cort icosteroids, chem otherapy, and radiat ion therapy.

    Mechanical pain is severe and m ovem ent related. It t ypically worsens w ith loading of the spine as a pat ient m oves from lying dow n to sit t ing and from sit t ing to standing. Bending often exacerbates the pain , and it is relieved w ith recum bency. It is typically associated w ith ver tebral collapse, as the weakened ver tebra is no longer able to support the m echanical loads p laced on it . It is im por tan t w hen assessing spine t um or pat ien ts to evaluate their pain w hen they are sit t ing or standing, because m echanical pain m ight not be noted in pat ients lying in bed. Mechanical pain m ust be dist inguished from local and radicular pain. It is often refractory to ant i-in am m atory m edicat ions, chem otherapy, and radiat ion . Although these m odalit ies m ay t reat the underlying tum or, they are not e ect ive at restoring the m echan-

    ical in tegrit y of the spine, and therefore are unlikely to provide durable relief of m echanical pain . Pat ients w ith m echanical pain t ypically require a t reatm ent aim ed at st rengthening the a ected spinal region, such as cem ent augm en-tat ion or spinal stabilizat ion .

    Mechanical InstabilityThe nal com ponent of the clin ical evaluat ion is to recognize the pat ient present ing w ith spinal instability. The SOSG has de ned neoplast ic spinal instabilit y as the loss of spinal in tegrit y as a result of a neoplast ic process that is associated w ith m ovem entrelated pain, symptom atic or progressive deform ity, and/or neural com prom ise under physiologic loads.20 Mechani-cal instabilit y due to spinal m etastasis is an indicat ion for surgical stabilizat ion or percutaneous vertebral augm entat ion, regardless of the ESCC grade or the chem o/radiosensit ivity of the tum or. Although e ect ive for local tum or con-t rol, chem otherapy and radiat ion therapy have lit t le or no im pact on spinal stability. As a result , pat ients w ith gross neoplast ic spinal instabilit y generally require a surgical in tervent ion.

    The assessm ent of spinal instability is based on a com binat ion of both clin ical and radiograph ic in form at ion . The SOSG has proposed a set of cr iter ia, the Spine Instabilit y Neoplast ic Score (SINS) (Table 1.1),20 to help clin icians evaluate instabilit y. This grading schem e is based on six param eters: locat ion of the lesion, presence and t ype of pain , radiographic alignm ent , nature of the lesion (lyt ic or blast ic), ver tebral body collapse, and posterior elem ent involvem ent. Each param eter receives a num erical score. Metastat ic spine lesions w ith a low SINS (06) are generally considered stable and do not require surgical in tervent ion , w hereas a h igh SINS (1318) suggests instabilit y that is likely to require surgical stabilizat ion . In term ediate SINS (712) tum ors are considered potent ially unstable and represent the m iddle of the instability spectrum . The SINS does not recom m end any speci c t reatm ent but is a guide to help both surgeons and nonsurgeons recognize those pat ien ts w ho m igh t be at r isk for p rogressive ver tebral collapse and deform it y. The SINS dem onst rated near perfect in ter and

  • Evaluation and Decision Making for Metastatic Spinal Tumors 5

    in t raobserver reliabilit y in determ in ing the th ree clin ically relevant categories of stabilit y: stable (SINS 06), potent ially unstable (SINS 712), and unstable (SINS 1318). The sensit ivit y and speci cit y for detect ing potent ially unstable or unstable lesions were 95.7% and 79.5%.13

    Oncological Status

    The th ird key elem ent of the evaluat ion of the pat ient w ith spinal m etastat ic disease is oncological status. Most im portantly th is includes recognit ion of the speci c tum or h istology. In addit ion, the extent of m etastat ic disease (bone, visceral) and the extent and nature of prior t reatm ent also have an im pact on the m anagem ent of the spine m etastasis.

    HistologyIt is cr it ical to ident ify the tum or h istology because it provides im portant inform at ion about the pat ien ts prognosis. In fact , the h istology of the prim ary tum or is the single st rongest predictor of postoperat ive survival in pat ients undergoing surgery for spinal m etastases.21,22 According to Tom ita et al,21 tum or histologies can be st rat i ed in to th ree groups: slow-grow ing tum ors, including breast , prostate, thyroid, and carcinoid tum ors; m oderately grow ing tum ors, including those arising from the kidney and uterus; and rapidly grow ing tum ors, including tum ors of the lung, liver, stom ach, esophagus, pancreas, bladder, sarcom a, and tum ors of unknow n origin . In general, the m ore aggressive the h istology, the worse the prognosis.

    Knowledge of the tum or h istology also provides crit ical inform ation regarding the respon

    Table 1.1 The Spinal Instability Neoplastic Score (SINS)

    SINS Component Description Score

    Location Junctional (occiput-C2, C7-T2, T11-L1, L5-S1) 3Mobile spine (C3-C6, L2-L4) 2Semi-rigid (T3-T10) 1Rigid (S2-S5) 0

    Paina Yes 3Occasional pain but not mechanical 1Pain-free lesion 0

    Bone lesion Lytic 2Mixed (lytic/blastic) 1Blastic 0

    Radiographic spinal alignment Subluxation/translation present 4De novo deformity (kyphosis/scoliosis) 2Normal alignment 0

    Vertebral body collapse > 50% collapse 3< 50% collapse 2No collapse with > 50% body involved 1None of the above 0

    Posterolateral involvement of spinal elementsb Bilateral 3Unilateral 1None of the above 0

    a Pain improvement with recumbency and/or pain with movement/loading of the spine.b Facet, pedicle or costovertebral joint fracture or replacement with tumor.Source: From Fisher CG, DiPaola CP, Ryken TC, et al. A novel classi cation system for spinal instability in neoplastic disease: an evidence-based approach and expert consensus from the Spine Oncology Study Group. Spine 2010;35:E1221E1229. Reproduced with permission.

  • 6 Chapter 1

    siveness of the spinal m etastasis to nonsurgical therapies such as chem otherapy and radiat ion therapy. The im pact of chem otherapy and radiotherapy var ies considerably w ith t um or t ype.23,24 Chem otherapy is generally reserved for asymptom at ic or m inim ally sym ptom at ic lesions because it s e ects t ypically take t im e to m anifest and th is m ay be problem at ic for sym ptom at ic pat ients. The obvious except ions to th is are the hem atologic m alignancies or Ew ings sarcom a, w hich m ay respond rapidly to chem otherapy. In pat ients w ithout neurologic de cit or spinal instabilit y, it m ay be perfectly reasonable to u t ilize system ic therapy for sensit ive h istologies. Breast and prostate cancers, for exam ple, can be quite sensit ive to horm onal therapies.25,26

    With regard to radiat ion , tum ors have t radit ionally been considered radiosensit ive or radioresistant depending on their response to conventional radiat ion therapy (CRT).23,24 With-out precise conform al technique, the dosing of CRT is lim ited by spinal cord tolerance, as the cord is w ith in the radiat ion eld that is used to t reat the tum or. Hence, a tum or that responds favorably to doses lim ited by cord tolerance is considered radiosensit ive, w hereas those that do not respond favorably to these doses are considered radioresistan t . In cases w here the t um or is in close proxim it y to the sp inal cord , it m ay be impossible to radiate the tum or w ithout radiat ing the cord, and the radiosensit ivit y of the tum or, therefore, w ill determ ine w hether th is m odalit y can be used e ect ively. Most au-thors consider lym phom a, myelom a, and sem inom a to be h ighly radiosensit ive and t reatable w ith CRT even in cases of sp inal cord com pression . Of the solid t um ors, breast , p rostate, ovarian , and neuroendocrine carcinom as are considered to be radiosensit ive, w hereas renal, thyroid, hepatocellu lar, nonsm allcell lung, colon, m elanom a, and sarcom a are considered radioresistant.17 Spinal stereotactic radiosurgery (SRS), w hich can be used to deliver h ighly conform al doses of radiat ion to spinal tum ors while avoiding the spinal cord , has been show n to provide excellent tum or control in a h istology independent m anner.13,24,27 However, this technique is lim ited w hen the t um or and spinal cord are in close proxim ity.

    Finally, it is im portant to ident ify the tum or t ype, as cer tain h istologies are par t icu larly hypervascular. Metastases from renal cell, thyroid, hepatocellular, m elanom a, and giant cell tum ors can all bleed substantially during tum or resect ion . Preoperat ive em bolizat ion can be very e ect ive in reducing in t raoperat ive blood loss.28 One m ust iden t ify hypervascular t um ors preoperat ively in order to take advantage of th is procedure.

    To con rm the h istology in a pat ient w ith a spinal tum or, percutaneous biopsy m ay be required. Th is is not generally necessary w hen a pat ient w ith a know n prim ary and act ive m etastat ic disease presents w ith a new spinal lesion. However, w hen there is no know n prim ary or w hen a pat ient w ith a know n prim ary has been w ithout act ive disease for a prolonged in terval, biopsy should be st rongly considered in order to con rm the diagnosis, to exclude a second prim ary, or to rule out a prim ary bone tum or. This m ay be part icularly true in patients w ho have a h istory of prior chem otherapy or radiat ion , w hich m ay increase the chance of a second m alignancy.

    Extent of Metastatic Disease/Systemic StagingIn addit ion to the t ype of tum or, the presence and exten t of ext raspinal m etastat ic disease have an im pact on decision m aking. The presence of addit ional visceral and bone m etastases adversely a ect s survival, w hich in tu rn m ay have an im pact on the choice of t reatm ent .21,22 This is the basis for the wellknow n Tom ita scoring system , w hich assigns point values to these three factors to generate a score, which in turn determ ines the aggressiveness of t reatm ent . Grade of m alignancy (slow grow th, 1 point; m oderate grow th, 2 points; rapid grow th , 4 poin ts), visceral m etastases (no m etastasis, 0 poin t s; t reatable, 2 poin ts: un t reatable, 4 poin ts), and bone m etastases (solitary or isolated, 1 point; m ult iple, 2 points) are used to generate a score from 2 to 10. A prognost ic score of 2 to 3 points indicates a w ide or m arginal excision for longterm local control; 4 to 5 points indicates m arginal or intralesional excision for m iddleterm local con

  • Evaluation and Decision Making for Metastatic Spinal Tumors 7

    t rol; 6 to 7 points indicates palliat ive surgery for shortterm palliat ion; and 8 to 10 points indicates nonoperat ive support ive care for end of life. Cancer therapies have evolved considerably since the publicat ion of th is paper. As a result the t reatm ents recom m ended based on the prognost ic score m ay no longer be opt im al. Nonetheless, the im pact of these prognost ic factors on survival is clear. Pat ients w ith extensive system ic disease have a poorer survival and are less likely to bene t from m ajor sur-gical procedures. Moreover, the increased disease burden m ay cause com orbidit ies (e.g., decreased pulm onary funct ion from lung m etastasis, coagulopathy from liver m etastasis), that render the pat ient less able to tolerate larger procedures. Therefore, staging is m andatory and should be perform ed in all pat ients prior to surgery, if possible.

    It is worth not ing the aforem ent ioned prognost ic factors characterized by Tom ita; tum or h istology, visceral m etastasis, and bone m etastasis, are also com ponents of the wellknow n Tokuhashi scoring system . In their system , Tokuhashi et al22 consider six key prognost ic factors: general condit ion , num ber of ext raspinal bone m etastases, num ber of m etastases in the ver tebral body, presence or absence of m etastases to m ajor internal organs, site of the prim ary lesion, and severit y of palsy. In addit ion to the prim ary site of the cancer (tum or h istology), they evaluate presence of m etastases to the m ajor in ternal organs and score these as irrem ovable, rem ovable, and none. They separate bone m etastases in to ext raspinal and vertebral classifying the form er as 3, 1 to 2, or 0, and the lat ter as 3, 2, or 1. Finally, they st ratify the general condit ion of the pat ient (Karnovsky Perform ance Status) as poor (1040), m oderate (5070), or good (80100), and the presence of spinal cord palsy as com plete, incom plete, or none. Each param eter is then assigned a range of scores to provide a m axim um total of 15. The score is then used to determ ine how aggressive a t reatm ent to select . Pat ients w ith lower scores are recom m ended for m ore conservat ive approaches, w ith h igher scoring pat ients receiving excisional surgeries. The consistency rate between the criteria for predicted prognosis and the actual survival period was

    h igh in pat ients w ith in each score range (08, 911, or 1215), 86.4% in th e 118 pat ien t s evaluated prospect ively after 1998, and 82.5% in all 246 pat ients evaluated ret rospect ively. The prognost ic cr iter ia scoring system were useful for predict ing the prognosis irrespect ive of t reatm ent m odalit y or local extension of the lesion.

    Extent of Previous TreatmentThe nal com ponent of the pat ients oncologi-cal status is the nature and extent of the prior therapy. This is not easy to st rat ify or quant ify, and it needs to be evaluated on a pat ientby pat ient basis; however, the concept is relat ively selfevident . Sim ply pu t , w hen consider ing t reatm ent opt ions for a pat ien t w ith sp inal m etastat ic d isease, the choice w ill be in u-enced by w hat therapies have already been ut ilized and the relat ive e cacy of the rem ain-ing t reatm ent st rategies. As an illust rat ive exam ple, a pat ient has m etastat ic breast cancer and a m idthoracic lesion that is abut t ing the cord , causing som e m ild radicu lopathy but no neurologic dysfunct ion . If th is pat ien t is therapy nave, t reatm ent opt ions m ay include convent ional radiotherapy, horm onal/chem otherapy (depending on receptor status), or surgery. But if th is lesion has been previously ir radiated and the pat ien t is receiving th irdline chem otherapy, nonsurgical opt ions m ay be lim ited, and surgery m ay be necessary if the prognosis is reasonable. The presence and proxim it y of p r ior radiat ion elds is often a determ ining factor regarding the e cacy or feasibilit y of subsequent radiat ion due to issues of spinal cord tolerance. Spinal SRS m ay help to m inim ize cord toxicit y but requires that there be som e degree of spat ial separat ion between the tum or and the neurologic st ructures.24,29 Clearly, pat ients w ho have received m ult iple prior therapies m ay be fur ther along in their overall disease t rajectory. This m ay re ect a decreased overall prognosis that m ust be considered prior to surgery.17,18 Collaborat ion am ong the m edical oncology, radiat ion oncology, and surgical team s is necessary to develop opt im al t reatm ent plans for these com plicated pat ients.

  • 8 Chapter 1

    Feasibility of the Surgical Plan

    The nal factor that m ust be considered before in tervening surgically for a sp inal m etastasis is the feasibilit y of the surgical plan . The goal of t reatm ent for spinal m etastat ic disease is palliat ion . Surgery m ust be able to reduce pain , restore and protect neurologic funct ion , and restore spinal stabilit y in a m anner that is durable over the rem aining life expectancy of the pat ien t and w ith acceptable m orbidit y. Qualit y of life should be enhanced. There is am ple evidence to suggest that surgery can help to ach ieve these goals, and in cer tain circum stances, par t icularly in the case of MESCC, m ay be the superior t reatm ent opt ion. In the case of h ighgrade MESCC, w hen com bined w ith postoperat ive radiat ion , surgery provides far superior outcom es than does radiat ion alone.9,10,30 Moreover, surgery m ay be the only m eans of correct ing sym ptom at ic spinal instabilit y. Last ly, surgery m ay be the best opt ion in cases w here chem otherapeut ic and radiotherapeut ic st rategies have failed or are otherw ise lim ited . However, surgery also tends to be am ong the m ost invasive t reatm ents for spinal m etastases and carries sign i cant potent ial for com plica-t ions. This is par t icularly relevant in a pat ien t populat ion that m ay have substan t ial com orbidit ies related to advanced age; underlying disease; prior t reatm ent w ith chem otherapy, radiat ion therapy, or steroids; and poor nut rit ional status.7,31,32

    In short , it is the responsibilit y of the spinal surgeon to carefully consider the surgical plan prior to taking a pat ient to the operat ing room . First , the surgeon m ust consider the st rategy for resect ion of the m etastasis. Will the resection be in t ralesional or en bloc? Given the palliat ive nature of surgery for m etastat ic disease, m ost resect ions are perform ed in a piecem eal fashion. However, there are som e circum stances (indolent h istology, solitary spinal m etastasis, long predicted survival) w here a m ore aggressive en bloc resect ion m ay be considered.33 In addit ion , for hypervascular h istologies, a preoperat ive em bolizat ion should be considered to reduce in t raoperat ive blood loss.28

    Second, the surgeon m ust consider the surgical approach. Often th is is a m at ter of individual preference; however, there are cer tain ly regional anatom ic const rain ts that m ay in u-ence th is decision, and these are discussed in a subsequen t chapter.13,34 There m ay also be factors related to the individual pat ien t that in uence the choice of surgical approach. For exam ple, the surgeon m ay w ish to avoid operating in a previously radiated or operated site in order to reduce wound healing com plicat ions and m ake the dissect ion easier.31 Alternat ively, it m ay not be feasible to consider a t ransthoracic approach in a pat ien t w ith com prom ised pulm onary function. It is imperative for the surgeon to consider w hether an access surgeon w ith addit ional expert ise m ight provide a safer and m ore sat isfactory surgical approach.

    Third, the surgeon m ust consider the st rategy for spinal reconst ruct ion and stabilizat ion . There are num erous devices, m ater ials, and techniques that are available for rebuilding the spine follow ing resect ion of a spinal m etastasis. It is beyond the scope of th is chapter to review th is topic or the biom echanical principles of spinal reconst ruct ion . However, there is one im portant point that the spine surgeon m ust contem plate in the spinal m etastasis pat ientthe qualit y of the pat ients bone. The stabilit y of a spinal reconst ruct ion and stabilizat ion relies on the im plan ts con tact ing and xat ing in to bone of sat isfactory qualit y. When th is is not the case, im plants can loosen and xat ion can be com prom ised, leading to spinal instability. The presence of tum or in adjacent or nearby ver tebra is one factor that can impact xat ion . Im aging studies should be scrut inized to m ake sure that there is lim ited tum or burden in ver tebra that is being relied on to provide adequate st ructural support . In addit ion , osteopenia and osteoporosis are com m on am ong cancer pat ients.35 This m ay be a byproduct of advanced age, fem ale sex, or t reatm ents for the underlying cancer including steroids, chem otherapy, horm onal therapy, and radiotherapy. Poor nut rit ional status m ay also lead to bone loss. The sp ine surgeon m ust recogn ize th is potent ial problem and avoid surgery, alter the reconst ruct ion p lan techn ique, or consider

  • Evaluation and Decision Making for Metastatic Spinal Tumors 9

    the adjunct ive use of ver tebral augm entat ion to im prove the st rength of the ver tebra and xat ion.

    Last ly, the sp ine surgeon m ust consider wound healing. A palliat ive spine surgery that decompresses the neurologic elem ents and stabilizes the spine is not successful if the pat ient is left w ith a nonhealing wound. This can lead to a prolonged hospital stay and, m ore im portantly, can delay the adm inist rat ion of m uchneeded system ic therapy. It is incum bent upon the surgeon to recogn ize factors that w ill im pede healing. These include pr ior radiat ion or surgery, chem otherapy, steroids, and m alnutr it ion . Obviously, if previous radiat ion and surgical elds can be avoided, th is is advanta-geous.31 However, th is is often not the case. If the surgery is elect ive, there m ay be t im e to discont inue chem otherapy or steroids and im prove the nut r it ional status of the pat ient . Unfortunately, m ost surgeries for spinal m etastat ic disease are done under m ore urgent circum stances. Therefore, the surgeon is frequen t ly left w ith a situat ion that requires surgery, but presen ts wound healing challenges. In these situat ions, we st rongly recom m end collaboration w ith a plast ic surgeon for im m ediate ap reconst ruct ion at the t im e of the surgical resect ion and stabilizat ion .36,37 The ut ilizat ion of local m uscle advancem ent aps, rotational aps, and even free t issue t ransfer at the t im e of the in it ial spine surgery can dram at ically reduce com plicat ions related to wound healing.

    Considerat ion of these aforem ent ioned factors w hen p lann ing surgery for sp inal m etastat ic disease w ill help avoid poorly conceived operat ions, reduce com plicat ions, and lead to im proved pat ient outcom es.

    Treatment Algorithms

    Utilizing the principles of evaluat ion and decision m aking outlined in th is chapter, several authors and inst itut ions have developed algorithm s for the m anagem ent of pat ients w ith spinal m etastases. Obviously, t reatm ent decisions m ust be m ade on an individual basis and

    not all pat ients w ill t neatly w ith in any pro-cedural fram ework. Moreover, each inst itu t ion w ill base its algorithm on the t reatm ent m odalit ies available w ith in that center. Nonetheless, it is inst ruct ive to see how the key factors described above are in tegrated in to two of the m ost com m only ut ilized t reatm ent algorithm s for pat ients w ith m etastat ic disease to the spine. These are the Algorithm for Spinal Metastases (Fig. 1.2) developed and prospect ively applied by Borian is group in Bologna since January 2002,3840 and the neurologic, oncological, m echanical, and system ic (NOMS) decision fram ework (Fig. 1.3) u t ilized during the past 15 years at Mem orial SloanKet tering Cancer Center.17

    In both t reatm ent paradigm s, a crit ical in it ial assessm ent is the overall m edical status of the pat ien t . In the Borian i algor ithm , th is is referred to as operabilit y, and in the NOMS it is the system ic assessm ent . Those pat ients unable to tolerate surgery are referred for radiation or m edical therapy. The next crit ical factor is the clinical presentat ion. In both fram eworks the degree of neurologic com prom ise (m easured either neurologically or by the degree of spinal cord com pression) directs a pat ient toward surgery unless the h istology is h ighly sensit ive to chem otherapy or convent ional radiat ion . Sim ilarly, the presence of spinal instabilit y (r isk of pathological fracture in Boriani) leads the pat ient toward a surgical rem edy. The oncological status of the patient is t ightly intertw ined w ith the clin ical presentat ion . In particular, the im pact of the tum or h istology on response to radiat ion and chem otherapy is a crit ical factor. Chem o and radiosensit ive h istologies are m ore likely to be m anaged w ith nonsurgical m odalit ies as long as there is no worsening neurologic comprom ise or spinal instabilit y. Resistant h istologies are directed toward surgery by Borianis algorithm . In NOMS, these tum ors m ay be t reated by spinal SRS (not available in Bologna) if the degree of cord com pression is low grade. For h ighgrade com pression w ith radioresistant h istology, separat ion surgery to rem ove the com pressive port ion of the tum or and stabilize the spine, followed by radiosurgery to the rem aining disease, is rec

  • 10 Chapter 1

    Fig. 1.2 Borianis Treatment algorithm for spinal metastasis. ASA, American Society of Anesthesiolo-gists; CHT, chemotherapy; CT, computed tomogra-phy; E.B., en bloc; Frankel, Frankel grading system; METS, metastases; NMR, nuclear magnetic reso-nance; PT., patient; RXT, radiation therapy; VP,

    vertbroplasty. (From Cappuccio M, Gasbarrini A, Van Urk P, Bandiera S, Boriani S. Spinal metastasis: a retrospective study validating the treatment algorithm. Eur Rev Med Pharmacol Sci 2008;12: 155160. Reproduced with permission.)

  • Evaluation and Decision Making for Metastatic Spinal Tumors 11

    om m ended.29 Im plicit in both of these fram eworks is that the surgeons carefully consider the feasibilit y of any t reatm ent plan in advance of its execut ion.

    Chapter Summary

    The appropriate m anagem ent of pat ients w ith m etastat ic spinal d isease requires an appreciat ion for the com plexit y of th is challenging clin ical condit ion . Spine surgeons w ho t reat pat ien t s w ith t um ors not on ly need to be exper t s in the techn ical aspects of perform ing spinal surgery, bu t also m ust have an understanding of oncological principles and nonsurgical t reatm ents available for these pat ients. This chapter reviewed the literature that serves as the basis for evaluat ion and decision m aking in the m anagem ent of pat ien ts w ith m etastat ic spinal disease. The factors relevant to a pat ients m edical tness to undergo surgery were dis-cussed, as was evaluat ion of com m on clin ical

    presen t ing sym ptom s, including pain , neurologic dysfunct ion, and m echanical instabilit y. This chapter also discussed evaluat ion of a patients oncologic status and the feasibilit y of surgery as par t of the t reatm ent plan . Com m only used m anagem ent algorithm s were reviewed. After reading th is chapter, the reader should have a basic understanding of the m any factors that need to be taken in to considerat ion w hen developing a plan to m anage a pat ien t w ith m etastat ic spinal disease.

    Pearls

    Manage spine tumor patients as part of a multi-disciplinary team.

    Understand what you are treating. Whenever possible, obtain a tissue diagnosis before operat-ing on a spine tumor.

    Have a well-thought-out operative plan. Consider factors such as the need to stage procedures, the need for approach surgeons, and the need for plastic surgeons. Have a plan for spinal recon-struction and stabilization.

    Fig. 1.3 Schematic description of the neurologic, oncological, mechanical, and systemic (NOMS) decision framework.17,29 cEBRT, conventional external beam radiation; ESCC, epidural spinal cord compression; SRS, stereotactic radiosurgery.

    (Adapted from Laufer I, Rubin DG, Lis E, et al. The NOMS framework: approach to the treatment of spinal metastatic tumors. Oncologist 2013;18: 744751.)

  • 12 Chapter 1

    Pitfalls

    Unnecessary or excessive surgery: Understand the patients prognosis and other treatment options available. Avoid major operations on patients with limited life expectancy or potential for recovery.

    Problems with wound healing: Consider using a plastic surgeon for local ap reconstruction. Use drains when necessary. Pay at tention to nutrition in the postoperative period. Implement a mobili-zation strategy to avoid pressure ulcers.

    Operating without a tissue diagnosis: Tumor his-tology provides crit ical information regarding prognosis, availability of adjuvant therapies, type of surgery required, and need for embolization. Most patients who present with metastatic spine tumors do not need emergent surgery. Most will achieve signi cant relief of symptoms with ste-roids. In the vast majorit y of cases there is t ime to establish the t issue diagnosis, obtain appro-priate multidisciplinary evaluation, and carefully plan surgery.

    ReferencesFive Must-Read References 1. Cancer Facts and Figures 2013. Am erican Cancer

    Societ y, 2013. h t tp ://w w w.cancer.org/acs/groups/con t e n t /@e p id e m io logysu r ve ilan ce /d ocu m e n t s /docum ent/acspc036845.pdf.

    2. Aaron AD. The m anagem ent of cancer m etastat ic to bone. JAMA 1994;272:12061209 PubMed

    3. Jacobs WB, Perrin RG. Evaluat ion and t reatm ent of spinal m etastases: an overview. Neurosurg Focus 2001;11:e10 PubMed

    4. Sundaresan N, Digiacin to GV, Hughes JE, Ca er ty M, Vallejo A. Treatm ent of neoplast ic spinal cord com pression: results of a prospect ive study. Neurosurgery 1991;29:645650 PubMed

    5. Bilsky MH, Lis E, Raizer J, Lee H, Boland P. The diagnosis and t reatm ent of m etastat ic spinal tum or. Oncologist 1999;4:459469 PubMed

    6. Constans JP, de Divit iis E, Donzelli R, Spaziante R, Meder JF, Haye C. Spinal m etastases w ith neurological m anifestat ions. Review of 600 cases. J Neurosurg 1983;59:111118 PubMed

    7. Choi D, Crockard A, Bunger C, et al; Global Spine Tum or Study Group. Review of m etastat ic spine tum our classi cat ion and indicat ions for surgery: the consensus statem ent of the Global Spine Tum our Study Group. Eur Spine J 2010;19:215222 PubMed

    8. Hatrick NC, Lucas JD, Tim othy AR, Sm ith MA. The surgical t reatm ent of m etastat ic disease of the spine. Radiother Oncol 2000;56:335339 PubMed

    9. Ibrahim A, Crockard A, Antoniet t i P, et al. Does spinal surgery im prove the qualit y of life for those w ith extradural (spinal) osseous m etastases? An international m ult icenter prospect ive observat ional study of 223 pat ients. Invited subm ission from the Join t Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2007. J Neurosurg Spine 2008;8: 271278 PubMed

    10. Patchell RA, Tibbs PA, Regine WF, et al. Direct decom pressive surgical resect ion in the t reatm ent of spinal cord compression caused by m etastat ic cancer: a random ised t r ial. Lancet 2005;366:643648 PubMed

    11. Kan P, Schm idt MH. Minim ally invasive thoracoscopic approach for anterior decom pression and stabilizat ion of m etastat ic spine disease. Neurosurg Focus 2008;25:E8 PubMed

    12. Got tfr ied ON, Dailey AT, Schm idt MH. Adjunct and m inim ally invasive techniques for the diagnosis and t reatm ent of ver tebral tum ors. Neurosurg Clin N Am 2008;19:125138 PubMed

    13. Paton GR, Frangou E, Fourney DR. Contem porary treatm ent strategy for spinal m etastasis: the LMNOP system . Can J Neurol Sci 2011;38:396403 PubMed

    14. Otsuka NY, Hey L, Hall JE. Post lam inectomy and postirradiat ion kyphosis in children and adolescents. Clin Orthop Relat Res 1998;354:189194 PubMed

    15. Fourney DR, AbiSaid D, Rhines LD, et al. Sim ultaneous anteriorposterior approach to the thoracic and lum bar spine for the radical resect ion of tum ors followed by reconst ruct ion and stabilizat ion . J Neurosurg 2001;94(2, Suppl):232244 PubMed

    16. Bilsky MH, Laufer I, Fourney DR, et al. Reliabilit y analysis of the epidural spinal cord com pression scale. J Neurosurg Spine 2010;13:324328 PubMed

    17. Laufer I, Rubin DG, Lis E, et al. The NOMS fram ework: approach to the t reatm ent of spinal m etastat ic tum ors. Oncologist 2013;18:744751 PubMed

    18. Sciubba DM, Pet teys RJ, Dekutoski MB, et al. Diagnosis and m anagem ent of m etastat ic spine disease. A review. J Neurosurg Spine 2010;13:94108 PubMed

    19. Gokaslan ZL. Spine surgery for cancer. Curr Opin Oncol 1996;8:178181 PubMed

    20. Fisher CG, DiPaola CP, Ryken TC, et al. A novel classi cat ion system for spinal instabilit y in neoplast ic disease: an evidencebased approach and expert consensus from the Spine Oncology Study Group. Spine 2010;35:E1221E1229 PubMed

    21. Tom ita K, Kawahara N, Kobayashi T, Yoshida A, Murakam i H, Akam aru T. Surgical st rategy for spinal m etastases. Spine 2001;26:298306 PubMed

    22. Tokuhashi Y, Matsuzaki H, Oda H, Oshim a M, Ryu J. A revised scoring system for preoperat ive evaluat ion

  • Evaluation and Decision Making for Metastatic Spinal Tumors 13

    of m etastat ic spine tum or prognosis. Spine 2005; 30:21862191 PubMed

    23. Maranzano E, Lat in i P. E ect iveness of radiat ion therapy w ithout surgery in m etastat ic spinal cord com pression: nal results from a prospect ive t r ial. Int J Radiat Oncol Biol Phys 1995;32:959967 PubMed

    24. Gerszten PC, Mendel E, Yam ada Y. Radiotherapy and radiosurgery for m etastat ic spine disease: w hat are the opt ions, indicat ions, and outcom es? Spine 2009; 34(22, Suppl):S78S92 PubMed

    25. Janni W, Hepp P. Adjuvant arom atase inhibitor therapy: outcom es and safety. Cancer Treat Rev 2010;36: 249261 PubMed

    26. Payne H, Khan A, Chow dhury S, Davda R. Horm one therapy for radiorecurrent prostate cancer. World J Urol 2013;31:13331338 PubMed

    27. Dam ast S, Wright J, Bilsky M, et al. Im pact of dose on local failure rates after im ageguided reirradiat ion of recurrent paraspinal m etastases. In t J Radiat Oncol Biol Phys 2011;81:819826 PubMed

    28. Roscoe MW, McBroom RJ, St Louis E, Grossm an H, Perrin R. Preoperat ive em bolizat ion in the t reatm ent of osseous m etastases from renal cell carcinom a. Clin Orthop Relat Res 1989;238:302307 PubMed

    29. Laufer I, Iorgulescu JB, Chapm an T, et al. Local disease cont rol for spinal m etastases follow ing separat ion surgery and adjuvant hypofract ionated or highdose singlefract ion stereotact ic radiosurgery: outcom e analysis in 186 pat ients. J Neurosurg Spine 2013;18: 207214 PubMed

    30. Villavicencio AT, Oskouian RJ, Roberson C, et al. Thoracolum bar vertebral reconstruct ion after surgery for m etastat ic spinal tum ors: longterm outcom es. Neurosurg Focus 2005;19:E8 PubMed

    31. Ghogawala Z, Mans eld FL, Borges LF. Spinal radia-t ion before surgical decom pression adversely a ects outcom es of surgery for sym ptom atic m etastat ic spinal cord compression. Spine 2001;26:818824 PubMed

    32. Mazel C, Balabaud L, Bennis S, Hansen S. Cervical and thoracic spine tum or m anagem ent: surgical indications, techniques, and outcom es. Orthop Clin North Am 2009;40:7592, vivii vivii. PubMed

    33. Murakam i H, Kawahara N, Dem ura S, Kato S, Yoshioka K, Tom ita K. Total en bloc spondylectomy for lung cancer m etastasis to the spine. J Neurosurg Spine 2010;13:414417 PubMed

    34. Fourney DR, Gokaslan ZL. Use of MAPs for determ ining the opt im al surgical approach to m etastat ic disease of the thoracolum bar spine: anterior, posterior, or com bined. Invited subm ission from the Join t Sect ion Meet ing on Disorders of the Spine and Peripheral Nerves, March 2004. J Neurosurg Spine 2005; 2:4049 PubMed

    35. Colem an RE, Lipton A, Roodm an GD, et al. Metastasis and bone loss: advancing t reatm ent and prevent ion. Cancer Treat Rev 2010;36:615620 PubMed

    36. Vitaz TW, Oishi M, Welch WC, Gerszten PC, Disa JJ, Bilsky MH. Rotat ional and t ransposit ional aps for the t reatm ent of spinal wound dehiscence and infections in pat ient populat ions w ith degenerat ive and oncological disease. J Neurosurg 2004;100(1, Suppl Spine):4651 PubMed

    37. Garvey PB, Rh ines LD, Dong W, Chang DW. Im m ediate softt issue reconst ruct ion for com plex defects of the spine follow ing surgery for spinal neoplasm s. Plast Reconst r Surg 2010;125:14601466 PubMed

    38. Gasbarrin i A, Cappuccio M, Mirabile L, et al. Spinal m etastases: t reatm ent evaluat ion algorithm . Eur Rev Med Pharm acol Sci 2004;8:265274 PubMed

    39. Cappuccio M, Gasbarr in i A, Van Urk P, Bandiera S, Bor ian i S. Spinal m etastasis: a ret rospect ive study validat ing the t reatm ent algorithm . Eur Rev Med Pharm acol Sci 2008;12:155160 PubMed

    40. Gasbarrin i A, Li H, Cappuccio M, et al. E cacy eva-luat ion of a new t reatm ent algorithm for spinal m etastases. Spine 2010;35:14661470 PubMed

  • Introduction

    Restorat ion or m aintenance of spinal stabilit y is an im portant object ive in the surgical t reat-m ent of spinal m etastasis, bu t is often ne-glected in set t ings of neurologic com prom ise. Indeed, a prospect ive random ized t r ial has dem onstrated the superiorit y of surgery and radiat ion therapy com pared to radiat ion ther-apy alone in the m anagem ent of h igh-grade spinal cord com pression for solid tum ors.1 Spi-nal instabilit y is a com m on and dist inct indica-t ion for surgery or vertebral augm entation w ith vertebroplasty or kyphoplasty.2 However, it has not been studied as r igorously as spinal cord com pression. This re ects the controversy that exists regarding tum or-related instabilit y. The biom echan ical and clin ical literature in th is area is rem arkably lim ited.3 Prior to the Spinal Instabilit y Neoplast ic Score, there were few clin ical criteria published, and none had been tested for reliabilit y or valid it y. The lack of standardized cr iter ia led to sign i can t var ia-t ion w ith regard to d iagnosis and t reatm ent indicat ions. In essence if the problem was not clearly de ned, it was very di cult to study. The concept of spinal instabilit y, however, re-m ains a crit ical and essent ial com ponent in the surgical decision-m aking process.

    Most often , spine surgeons rely on clin ical exper ience to determ ine if in stabilit y is p res-en t . Although challenging for the sp ine sur-geon, the diagnosis of instabilit y is even m ore

    di cult for the nonsurgeon (radiologist , oncol-ogist), potent ially leading to inappropriate re-ferrals or pat ients w ith instabilit y being under t reated, r isking pain , deform ity, or neurologic deteriorat ion .

    This chapter reviews som e of the principles of biom echanics as they relate to pat terns of in-stability and deform ity that occur in neoplast ic disease, describes and applies the SINS in illus-trat ive cases, and discusses the unique anatom ic and biom echanical features of the di erent re-gions of the spine and options for m anagem ent.

    Principles

    De nition of Tumor-Related Spine InstabilityUnlike the appendicular skeleton, the spine presen ts a very com plex environm ent in w hich to judge tum or-related instabilit y. Metastat ic cancer alters both the m aterial and geom etric propert ies of the bonethe two ent it ies that form the st ructural property r igidit y. Although these proper t ies determ ine the resist ance to axial bending and t w ist ing loads in bone, the bone or ver tebras resistance to load in the spine is unique and signi cant ly in uenced by the region and adjacent anatomy. Indeed, there can be fracture or collapse in the spine, but no clin ical sym ptom s, deform ity, or fracture pro-gression. The in n ite com plexity has led to a

    2Neoplastic Spinal InstabilityDaryl R. Fourney and Charles G. Fisher

  • Neoplastic Spinal Instability 15

    sim pler approach in t rying to de ne and pre-dict spinal in stabilit y in the set t ing of m eta-stat ic disease. The Spine Oncology Study Group (SOSG) de nes spine instabilit y as loss of spi-nal in tegrit y as a result of a neoplast ic process that is associated w ith m ovem ent-related pain , sym ptom at ic or progressive deform ity, or neu-ral com prom ise under physiological loads.4

    Basic Biomechanical Principles in Spine Tumors Versus TraumaTum or-related instabilit y is very dist inct from high-energy t raum atic injuries in the pat tern of bony and ligam entous involvem ent , neurologic m anifestat ions, and bone qualit y. In addit ion , the abilit y of the spine to heal is com prom ised by the t um or, system ic therap ies, ir radiat ion , and the general biological com prom ise of these pat ients.5

    Principle 1: Load Sharing

    Disease that involves the cancellous core of the ver tebral body w ith preservat ion of the cor t i-cal bony support m ay not result in instabilit y. Taneichi et al6 analyzed radiological and clin i-cal data from patients w ith thoracic and lum bar m etastases and created a m ult ivariate logist ic regression m odel to ident ify the probabilit y of collapse under various states of tum or involve-m ent . They found that in the thoracic spine, dest ruct ion of the costovertebral join t was a m ore im portant r isk factor for collapse than the size of the m etastat ic lesion w ith in the ver-tebral body, presum ably related to loss of st i -ness and st rength norm ally provided by the r ib cage. In the thoracolum bar and lum bar spine, the m ost im portant factor for collapse was the size of the vertebral body defect . Involvem ent of the pedicle had a m uch greater in uence on ver tebral collapse com pared w ith the thoracic spine. Other studies have suggested that bone m ineral density is m ore im portant than defect size in predict ing fracture threshold.

    Principle 2: Tension Band

    Anter ior com pressive forces are balanced by a poster ior system com posed of m uscles and

    ligam ents working under tension . The well- vascular ized ver tebral bodies are the m ost com m on sites of t um or involvem ent , w ith poster ior ver tebral elem ents being m uch less frequently a ected. In general, the dorsal liga-m entous com plex is less com m only disrupted by neoplasm as com pared w ith h igh-velocity t raum a.5 Iat rogen ic dest ruct ion of poster ior elem ents by lam inectomy is probably m ore com m on than disrupt ion by the tum or itself. Dest ruct ion of the facet join ts by tum or is also rarer than in t raum a, but w hen it is present , it m ay result in signi cant t ranslat ional or rota-t ional deform ity.

    Impending CollapseThe biom echanical e ects of spinal m etastases are poorly de ned. As a result , there are no standards for predict ing the r isk of pathologi-cal fracture, even w hen lesions have been iden-t i ed and characterized w ith m odern im aging studies. Theoret ically, ver tebral body collapse m ay be prevented by radiat ion therapy or sys-tem ic therapies if the tum or is sensit ive to one of those t reatm ents and it s grow th (and there-fore lyt ic dest ruct ion of the ver tebra) can be arrested. Once the tum or reaches a crit ical size, w hich m ay be de ned as im pending collapse, only surgical prophylact ic stabilizat ion (e.g., percutaneous cem ent , pedicle screws) can pre-vent fracture. Unfortunately, a reliable m ethod to predict im pending collapse does not exist due to the regional biom echan ical and ana-tom ic issues. Therefore, t reatm ent of instabil-it y should generally be on the basis of actual clinical instability rather than asymptom atic or relat ively asym ptom at ic radiological ndings that im ply the potent ial for instabilit y in the future.

    Spinal Instability Neoplastic ScoreIn the SINS classi cat ion system , tum or-related instabilit y is assessed by adding together six individual com ponen t scores: sp ine locat ion , pain , lesion bone qualit y, radiograph ic align-m ent , ver tebral body collapse, and postero-lateral involvem ent of the spinal elem ents

  • 16 Chapter 2

    (see Table 1.1). Each com ponen t of SINS has dem onst rated clin ically acceptable reliabilit y.7

    The m inim um score is 0 and the m axim um is 18. Total SINS scores have near-perfect inter- and intraobserver reliability when collapsed into three clin ically relevant assessm ents of tum or- related instabilit y, w hich can be described as stability (06), indeterm inate instability (poten-t ially unstable) (712), and instabilit y (1318). Surgical consultat ion is recom m ended for pa-t ients w ith SINS scores 7. Exam ples of scoring are presented in Figs. 2.1, 2.2, and 2.3 .

    Content and face validit y of the SINS was fa-cilitated by in tegrat ing the best evidence pro-vided by two system at ic reviews w ith expert consensus from m em bers of the SOSG.4 At the t im e of th is w rit ing, there are no prospect ive studies that have assessed SINS. However, a ret rospect ive valid it y analysis found that the false-negat ive rate was low (4.3%), and all of these t ype II errors were due to dist inguishing stable from poten t ially unstable cases (not stable vs unstable).7

    When Is Vertebroplasty or Kyphoplasty Su cient for Stabilization?Assigning a num erical grade to instability (SINS 018) is at t ract ive because it recognizes that , unlike in t raum a, spinal stabilit y due to tum or is not lost suddenly in an all-or-none fashion. Instead, it is gradual process that at a cer tain point results in pathological fracture. By being able to reliably de ne the severit y of instabilit y we m ay com e closer to understanding the indi-cat ions for less invasive form s of stabilizat ion such as ver tebroplasty or kyphoplast y. We pro-pose that pat ien t s w ith in term ediate grades of instabilit y (SINS 712) are m ore likely to be appropriate candidates for percutaneous cem ent , w hereas those w ith h igher scores m ay be bet ter t reated w ith spinal inst rum entat ion .8 Vertebral augm entat ion is part icularly useful in pat ients w ith lim ited life expectancy, pat ients w ho are too m edically frail to have open sur-gery, and pat ients w ith very poor bone qualit y (e.g., myelom a bone disease).9

    Treatment of Instability by Spinal RegionCraniovertebral Junction

    Metastasis in th is region rarely cause m yelop -athy because the upper cervical canal is large, and because tum ors in th is region typically presen t w ith severe m echanical neck pain be-fore they becom e large enough to signi cantly com press the sp inal cord . Therefore, ven t ral tum or resect ion (via a t ransoral or ext raoral approach) is rarely indicated, and our surgical m anagem ent st rategy has focused on posterior spinal stabilizat ion .10 We favor occipitocervical xat ion over shor t -segm ent approaches be-cause it protects the pat ient against the poten-t ial loss of st abilit y due to progression of the dest ruct ive process. Our goal is to obtain a durable const ruct so that the use of any cum -bersom e and poorly tolerated external orthoses (e.g., r igid collar or halo vest) can be avoided.

    Subaxial Cervical Spine

    From C3 through C6, corpectomy reconstructed w ith a cage and plate is the m ost com m on approach . A com bined an ter ior/poster ior sta-bilizat ion is often necessary for m ult ilevel d is-ease, circum ferent ial tum or involvem ent, severe instabilit y/deform it y, and poor bone qualit y. Supplem ental poster ior stabilizat ion is often required at the C7/T1 junct ion.11

    Thoracic and Lumbar Spine

    Anterior approaches are not feasible in m ost pat ients from T2 to T5, due to the great vessels and the hear t . Posterolateral approaches (cos-tot ransversectomy or lateral ext racavitary ap -proach) are recom m ended for th is region, and are also increasingly popular from T6 through L5 (as com pared w ith anterior approaches), because they allow rem oval of the tum or and the applicat ion of sp inal inst rum entat ion as a single-stage operat ion .12 Regardless of the approach used, the ver tebral body m ay be re-constructed w ith various m aterials, including al-lograft bone, polym ethylm ethacrylate (PMMA), or m etal cages. The lat ter include dist ract ible

  • Neoplastic Spinal Instability 17

    Fig. 2.1ae Computed tomography (CT) images of (a) select left parasagit tal view, (b) select midline sagit tal view, (c) select right parasagit tal view, (d) representative coronal view, and (e) axial view at L2 of a 42-year-old woman with known meta-static breast cancer who had an asymptomatic L2 lesion identi ed as an incidental nding on CT imaging. She denies any back pain. The Spine

    Instability Neoplastic Score (SINS) is calculated as follows: mobile spine location (L2), 2 points; pain-free lesion, 0 points; mixed lytic/blastic lesion, 1 point; normal spinal alignment, 0 points; no vertebral body collapse but > 50% body involve-ment, 1 point; no posterolateral spinal element involvement, 0 points. Total SINS = 2 + 0 + 1 + 0 + 1 + 0 = 4 (stable lesion).

    ed

    cba

  • 18 Chapter 2

    Fig. 2.2ae Computed tomography (CT) images of (a) select left parasagit tal view, (b) select midline sagit tal view, (c) select right parasagit tal view, (d) representative coronal view, and (e) axial view of a L5 lesion in a 49-year-old man with multiple myeloma who presents with mild low back pain that is not aggravated by activities or movement. The SINS is calculated as follows: junctional location, 3 points; pain but not mechanical, 1 point; lytic, 2 points; spinal alignment preserved, 0 points; < 50% vertebral body collapse, 2 points; unilateral replacement of right pedicle with tumor, 1 point. Total SINS = 3 + 1 + 2 + 0 + 2 + 1 = 9 (potential instabilit y, surgical referral recommended).

    a b

    c d

    e

  • Neoplastic Spinal Instability 19

    or telescoping variet ies. Polym ethylm ethacry-late is biologically com pat ible and very stable in com pression, but usually requires anchoring w ith Steinm ann pins or a chest tube. If ver te-brectomy has been perform ed via an anterior

    approach, anterior colum n reconst ruct ion and stabilizat ion w ith a plate w ithout supplem en-tary posterior stabilizat ion m ay be su cient , except in certain circum stances: signi cant ky-phosis or deform ity, such as translat ion; thora-

    Fig. 2.3ae Computed tomography (CT) images of (a) select left parasagit tal view, (b) select midline sagit tal view, (c) select right parasagit tal view, (d) representative coronal view, and (e) axial view of a C4 lesion in a 54-year-old woman with known metastatic sarcoma who presents with neck pain exacerbated by any movement and improved with

    application of a cervical collar. The SINS is calculated as follows: mobile spine location, 2 points; mechani-cal pain, 3 points; lytic lesion, 2 points; kyphotic deformity, 2 points; > 50% collapse, 3 points; bilateral posterolateral involvement, 3 points. Total SINS = 2 + 3 + 2 + 2 + 3 + 3 = 15 (instability, surgical referral recommended).

    ed

    cba

  • 20 Chapter 2

    colum bar junct ion zone; sign i can t adjacen t chest wall resect ion (e.g., Pancoast tum or or locally invasive sarcom a); ver tebrectomy span-ning two or m ore levels; ver tebrectomy caudal to L4 (anterior xat ion devices are di cult to apply in th is region); and poor bone qualit y.13

    Lumbosacral Junction and Sacrum

    Tum ors in th is region, in our experience, sel-dom cause spondylolisthesis or other obvious deform ity because the st rong ligam entous sup-port st ructures and the L5-S1 facet com plex, w hich confer m ost of the stabilit y in th is re-gion, are seldom completely disrupted by tum or. Although signi cant deform ity is unusual, clin-ical instabilit y w ith m echanical pain is not un-com m on, as th is region experiences the largest loads encountered in the ent ire spine. As w ith the cervicothoracic and thoracolum bar regions, the lum bosacral junct ion is a high-st ress re-gion. Relat ively abrupt changes in anatomy and regional m echanics between the m obile lum -bar and xed sacral segm ents increase the r isk of fracture and instabilit y and present chal-lenging problem s in term s of spinal stabiliza-t ion . Although sacral instabilit y is uncom m on,14 w hen it is p resen t the const ruct dem and is h igh and we generally recom m end providing m ore stability than less. We recom m end large- diam eter pedicle screws at S1 (7 to 8 m m ), sup -plem ented w ith addit ional sacral alar screws or iliac screws, favoring the later. With signi cant involvem ent of the sacrum and sacroiliac (SI) join t s, percu taneous iliosacral or t ranssacral screws should be used. These can often be sup -plem ented w ith cem ent th rough a sm all open incision .

    Correction of Spinal DeformityIn general, spinal deform it ies that ar ise as a re-sult of m etastasis are secondary to collapse of the ver tebral body. Therefore, w ith the excep-t ion of the upper cervical sp ine, w here t rans-lat ional and rotat ional deform it ies m ay occur, neoplast ic deform ity is usually a kyphot ic de-form ity. With sign i cant chest wall disrupt ion , or the loss of posterolateral elem ents (costo-

    ver tebral join t , facet , pedicle), kyphoscoliosis m ay be seen. Occasionally, shearing forces m ay lead to spondylolisthesis.

    A second feature of neoplast ic deform it ies is that they are usually exible. The m ajorit y m ay be corrected by careful posit ioning of the pa-t ient on the operat ing room table. After ver te-brectomy, a dist ract ible cage is a sim ple tool to correct m ost kyphotic deform it ies. Another op-t ion under the r ight condit ions is to shorten the spine by com pressing on norm al bone once the tum or is rem ovedanalogous to a pedicle subtract ion osteotomy. Except ions are cer tain upper cervical deform it ies (e.g., pathological dens fracture w ith t ranslat ion , rotatory at lan-toaxial sublu xat ion), w hich m ay require the applicat ion of cervical t ract ion .

    Is Bone Fusion Necessary?Bony fusion per se is un likely to be ach ieved in m any cancer pat ients, due to (1) lim ited life expectancy, (2) adjuvant chem otherapy or ra-diat ion therapy that fur ther com prom ises the chance of successful fusion, or (3) poor general tness (bone qualit y, nu t r it ion , or general frailt y). Our goal is to provide an im m ediately stable const ruct that m inim izes or elim inates axial pain and helps to prevent neurologic de-teriorat ion during the rem aining life span. In line w ith these principles, bracing is generally avoided as well. Allograft is often applied after stabilizat ion in order to prom ote fusion for the occasional long-term survivor. However, we do not favor the use of au tograft because of the potent ial for graft-site m orbidity and the occurrence of unrecognized m etastat ic disease w ith in the iliac crest bone of som e pat ients.

    Potential Problems

    Mechanical PainEven in the absence of obvious ver tebral body collapse or deform ity, som e clin ical instabilit y is assum ed to be present w hen the syndrom e of m echanical pain is present . This t ype of pain is characterist ically aggravated by m ovem ents

  • Neoplastic Spinal Instability 21

    and im proved or relieved at rest . It is im portant to dist inguish th is from local (biological) pain , w hich does not characterist ically change w ith m ovem ent . Often biological pain and m echan-ical pain occur together in m etastat ic disease.

    Vertebral Compression Fractures After RadiosurgeryRadiation therapy has developed new treatm ent paradigm s over the last decade. In pat ien ts w ith m in im al epidural d isease, stereotact ic body radiat ion therapy (SBRT) can be used to deliver radiat ion m ore precisely to the tum or, sign i can t ly reducing the dose to the spinal cord , and allow ing greater dose-delivery per fract ion . Th is advance allow s durable t um or control rates independent of tum or h istology- speci c radiosensit ivit y to convent ional exter-nal beam radiat ion therapy (cEBRT). In other words, historically radioresistant tum ors such as renal cell carcinom a m ay be t reated w ith SBRT. As well, SBRT m ay be used in pat ients in w hom cEBRT has failed.

    Higher doses produce superior local con-t rol bu t m ay be associated w ith late toxicit ies not associated w ith cEBRT, including ver tebral com pression fracture (VCF). Radiat ion myelop-athy is st ill a rare toxicit y unlike the reported data for VCF after SBRT. A series from the Me-m orial Sloan-Ket tering Cancer Center rst re-por ted a fracture progression rate of 39% of 71 sites t reated.15 The M.D. Anderson Cancer Center later reported a rate of 20% of 123