OtOlOgy, NeurOtOlOgy, aNd Skull BaSe Surgery

CliNiCal refereNCe guide

Theodore R. McRackan, MD Derald E. Brackmann, MD

v

CONteNtS

Foreword by Harold C. Pillsbury, MD xiIntroduction xiiiAcknowledgments xvAbout the Editors xviContributors xvii

Section I History of Neurotology 1

Chapter 1 History of Neurotology and Skull Base Surgery 3Lawrence R. Lustig

Section II Embryology Anatomy Physiology 13

Chapter 2 Embryological Development of the Ear 15Theodore R. McRackan and George B. Wanna

Chapter 3 Anatomy and Physiology of the Auditory System 23Gregory J. Basura and Steven A. Telian

Chapter 4 Anatomy and Physiology of the Vestibular System 33Gregory T. Whitman and Timothy C. Hain

Section III Evaluation 45

Chapter 5 The Neurotologic Examination 47Stanley Pelosi

Chapter 6 Hearing Assessment 55René H. Gifford

Chapter 7 Vestibular Testing 67Yuri Agrawal

Chapter 8 Intraoperative Monitoring 75Christopher K. Giardina and Oliver F. Adunka

Section IV Common Otologic Symptoms 83

Chapter 9 Tinnitus 85Theodore R. McRackan and John C. Goddard

vi Otology, Neurotology, and Skull Base Surgery: Clinical Reference Guide

Chapter 10 Otalgia and Temporomandibular Joint Disorders 93Jason A. Beyea and Aaron C. Moberly

Section V Hearing Loss 99

Chapter 11 Congenital and Genetic Hearing Loss 101Seiji B. Shibata and Richard J. Smith

Chapter 12 Otosclerosis 111Felipe Santos and Michael J. McKenna

Chapter 13 Presbycusis 119Simon I. Angeli

Chapter 14 Noise-Induced Hearing Loss 125Brian S. Chen and William M. Luxford

Chapter 15 Traumatic Injuries to the Ear 131Bradley W. Kesser

Chapter 16 Autoimmune Inner Ear Disease 141M. Jennifer Derebery

Chapter 17 Sudden Sensorineural Hearing Loss 149David S. Haynes and Jacob B. Hunter

Chapter 18 Ototoxicity 157Joseph T. Breen and Jeffrey T. Vrabec

Chapter 19 Rare Causes of Hearing Loss 169Oliver F. Adunka and Craig A. Buchman

Section VI Otologic Infections 177

Chapter 20 Otitis Externa 179Theodore R. McRackan and Marc L. Bennett

Chapter 21 Otitis Media 187Sujana S. Chandrasekhar

Chapter 22 Cholesteatoma 197Brendan P. O’Connell and Ted A. Meyer

Chapter 23 Petrous Apicitis and Intracranial Infection 209Anthony Myint, Joel Lavinsky, John L. Go, and Rick A. Friedman

CONTENTS vii

Section VII Hearing Rehabilitation 221

Chapter 24 Hearing Aids 223Monica M. Andriacchi and John W. House

Chapter 25 Implantable Hearing Devices 233Sohit Kanotra and Moises A. Arriaga

Chapter 26 Cochlear Implants 247Robert F. Labadie

Chapter 27 Auditory Brainstem Implants 259Daniel S. Roberts and Eric P. Wilkinson

Section VIII Skull Base Disorders 267

Chapter 28 Skull Base and Intracranial Anatomy 269C. Eduardo Corrales and Robert K. Jackler

Chapter 29 Vestibular Schwannoma 281Theodore R. McRackan and Derald E. Brackmann

Chapter 30 Meningiomas 291Colin L. W. Driscoll

Chapter 31 Neurofibromatosis Type II 301Brian S. Chen and William H. Slattery III

Chapter 32 Stereotactic Radiosurgery in Neurotology 309P. Ashley Wackym, Andrew Y. Kee, and Norman Jed Schroeder

Chapter 33 Temporal Bone Malignancy 321Paul W. Gidley

Chapter 34 Jugular Foramen Lesions 331Theodore R. McRackan and James L. Netterville

Chapter 35 Lesions of the Cerebellopontine Angle and 341 Petrous ApexDavid R. Friedmann, J. Thomas Roland, Jr., and Sean O. McMenomey

Chapter 36 Cerebrospinal Fluid Leaks and Encephaloceles 351Jeffrey D. Sharon and Howard W. Francis

viii Otology, Neurotology, and Skull Base Surgery: Clinical Reference Guide

Chapter 37 Complications from Neurotologic Surgery 361Marc S. Schwartz

Section IX Vestibular Disorders 371

Chapter 38 Bedside Vestibular Evaluation 373Evan Graboyes and Joel Goebel

Chapter 39 Ménière’s Disease 389Cameron C. Wick, Maroun T. Semaan, and Cliff A. Megerian

Chapter 40 Benign Paroxysmal Positional Vertigo 401Judith A. White

Chapter 41 Superior Semicircular Canal Dehiscence Syndrome 409Heather M. Weinreich and John P. Carey

Chapter 42 Labyrinthitis and Vestibular Neuronitis 419Edward I. Cho

Chapter 43 Vestibular Migraine 427Michael Thomas Teixido

Chapter 44 Nonotologic Causes of Dizziness 439Timothy C. Hain and Marcello Cherchi

Chapter 45 Vestibular Therapy 449Elizabeth Grace Georgelos

Section X Facial Nerve 459

Chapter 46 Embryology and Anatomy of the Facial Nerve 461Matthew L. Carlson and Alex D. Sweeney

Chapter 47 Electrodiagnostic Testing of the Facial Nerve 473Joseph P. Roche and Marlan R. Hansen

Chapter 48 Acute Facial Nerve Palsy 481Joseph P. Roche and Bruce J. Gantz

Chapter 49 Primary Facial Nerve Tumors 493Alejandro Rivas and Theodore R. McRackan

Chapter 50 Facial Nerve Rehabilitation 501Caroline A. Banks and Tessa A. Hadlock

CONTENTS ix

Section XI Pediatric Otology 511

Chapter 51 Hearing Loss Syndromes 513Lourdes Quintanilla-Dieck and Steven Goudy

Chapter 52 Congenital Aural Atresia 525Paul R. Lambert

Section XII Other Otologic Considerations 531

Chapter 53 Otologic Manifestations of Systemic Disorders 533J. Eric Lupo

Chapter 54 External Auditory Canal Lesions 545Elliott D. Kozin and Daniel J. Lee

Chapter 55 On the Horizon 553Justin S. Golub and Ravi N. Samy

Index 563

xi

fOrewOrd

This remarkable text, edited by Drs. McRackan and Brackmann, is a sig-nificant addition to our armamentarium of references in the field of otol-ogy, neurotology, and skull base surgery. The chapters are well-written and encompass the scope of the subspecialty. Each author is a well-recognized expert in their field and the format of the chapters by outline is extremely easy to follow. It is an outstanding reference for residents, fellows, and practicing otolaryngologists as well as neurotologists. The text is simplis-tic and easily addresses any question that may arise in the mind of the reader. This is clearly a reference guide. No attempts have been made to increase the prose to describe the topics, but that is not to say that the key issues are hard to assess using the format. The editors are to be com-mended in formulating a text that is extremely user-friendly to the reader. In these days where the majority of information we seek is available on the Internet, this particular book will be a completely different offering that will be a welcome addition to anyone’s library. I look forward to receiving my copy!!!

— Harold C. Pillsbury, MD Professor and Chief

Otolaryngology-Head and Neck Surgery The University of North Carolina at Chapel Hill

281

Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282Pathophysiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282Presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Diagnosis and Evaluation . . . . . . . . . . . . . . . . . . . . . 284Natural History . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286Microsurgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286Radiosurgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

chapter

29Vestibular Schwannomatheodore r. mcrackan and derald e. Brackmann

282 Otology, Neurotology, and Skull Base Surgery: Clinical Reference Guide

NOMENCLATuRE

• Virchownamedlesionneuromaduetoparallelfibersonhistologyappear to be axons

• Initiallythoughttobecochlearoriginduetoassociatedhearingloss• MurreyandStoutdiscoveredorigincelltobeSchwanncell• Preferrednameiscurrentlyvestibularschwannoma(VS)although

acoustic neuroma is still widely used

EPIDEMIOLOGY

• Representapproximately6%ofallintracranialtumors• ProspectiveDenmarkdatabaseestimateapproximately20VSper1

million population• Incidenceincreasingduetoawarenessandimprovedimagingaccess

and quality 1. 7.8 VS/million 1976 to peak 23 VS/million year 2004

• Tumorsizeattimeofdiagnosishasdecreasedfrom30mminmid-1970s to current 10 mm

• Meanageatdiagnosishasalsodecreasedfrom58yearsto49years

PATHOPHYSIOLOGY

• Arisefromvestibulardivisionofeighthcranialnerve 1. More commonly the inferior vestibular nerve

• VSdonotlikelyarisefromObersteiner-Redlichtransitionzone(glial-schwannian junction) as initially thought 1. Most tumors form lateral to the Obersteiner-Redlich transition

zone; oligodendrocytes produce myelin medial to junction and Schwann cells lateral

2. Greatest density of Schwann cells lies at Scarpa’s ganglion; VS likely arise from Schwann cell population associated with the Scarpa’s (vestibular) ganglion; like VS, Scarpa’s ganglion can lie near junction but also at various locations

• UnderstandingofgeneticoriginsofsporadicVSisstilluncertain; tumor biology is mostly understood through studying Neurofibromatosis type II (see Chapter 31)

• Therearetwohistologicalpatterns;AntoniAaredenselypackedcells with an organized whirled appearance (Verocay body); Antoni B are more loosely packed collection of vacuolated pleomorphic cells; Antoni B may occur more frequently in large tumors 1. Stain positive for S-100

CHAPTER 29 Vestibular Schwannoma 283

PRESENTATION

• Hearinglossismostcommonpresentingsymptomandpresentin95% of patients 1. Typically gradual onset unilateral sensorineural hearing loss 2. During clinical course up to 26% of patients report sudden onset

SNHL 3. Normal hearing patients are more likely to have tumors <1 cm

• AAO-HNShasstandardizedhearingreportinginVS(Table 29–1)• Vertigo/dysequilibriumismostcommonpresentationinpatientswith

normal hearing 1. Occurs in 20–50% of patients 2. Vertigo typically occurs relatively early in symptomology due to

peripheral nerve disturbance but can spontaneously resolve 3. Dysequilibrium typically occurs late in course due to cerebellar

involvement 4. Due to slow rate of tumor growth, majority of patients

compensate• Tinnitusreportedin53–70%ofpatients

1. Variable in nature 2. Asymmetric tinnitus without hearing loss should warrant

investigation for retrocochlear pathology• Trigeminalnervesymptomsoccurinapproximately20%ofpatients

1. Most commonly malar hypesthesia or parasthesiaa. Can result in absent or decreased corneal reflexesb. Very rare in tumors <1 cm, but occurs in 20% of patients with

1–3 cm tumors and 50% in tumors larger than 3 cm 2. Given high prevalence of headache in general popular, hard

to establish association with acoustic neuromas; vestibular schwannoma-related headaches are likely dull with mild to moderate intensity

TABLE 29–1. American Academy of Otolaryngology-Head and Neck Surgery Hearing Classification after VS Surgery

Hearing Class PTA SDS

A ≤30 ≥70%

B 31–50 50–71%

C >50 >50%

D Any <50%

Note. PTA = pure-tone average; SDS = speech discrimination score.

284 Otology, Neurotology, and Skull Base Surgery: Clinical Reference Guide

• Facialnerve(FN)dysfunctionisrelativelyuncommon(<10%ofpatients) 1. Can present as facial twitching or paralysis/paresis 2. Either symptom should raise concern for primary facial nerve

tumor• Latesymptomsaremuchlesscommontodayduetoearlydetection

1. Increased intracranial pressure from hydrocephalus can result in nausea/emesis, diplopia, papilledema, and lethargy to obtundation

2. Lower cranial nerve symptoms of hoarseness, dysphagia, and dysarthria are rare in modern era

DIAGNOSIS AND EVALuATION

• Audiologicevaluation 1. Pure-tone audiogram (PTA) and speech discrimination scores

(SDS) show wide variability from normal to no response 2. Rollover (worsened SDS with increasingly loud presentation)

and acoustic reflex decay (acoustic reflex fades during prolonged presentation of signal) were once thought to be good markers for retrocochlear pathology; over time these have been found to be poorly reliable

• Auditorybrainstemresponse(ABR)testing 1. Attractive as screening tool because it is noninvasive, inexpensive,

and rapid 2. The interaural wave I to V latency difference (IT5) is most

reliable screening measure for VS; latency of 0.2 ms or more is considered abnormal

3. Sensitivity ranges from 63–95%a. Highest sensitivity with tumors larger than 2 cm (100%)b. Decreased to 60% with tumors less than 1 cm

4. Stacked ABR increases sensitivity to 95% for all tumors• Electronsytagmography

1. Abnormal results in 98% of superior vestibular tumors and 60% inferior vestibular nerve tumors

2. Reduced ipsilateral caloric response and spontaneous nystagmus to contralateral side are common findings

3. Wide variety of findings in larger tumors including: abnormal saccadic pursuit, bilateral horizontal gaze nystagmus, and failed fixation suppression

4. Can be used to help identify vestibular nerve of origin in planning for hearing preservation surgery for middle cranial fossa surgery (discussed later)

CHAPTER 29 Vestibular Schwannoma 285

• MagneticResonanceImaging 1. Isotense or hypotense on T1 and T2, but enhance with

gadolinium 2. VS are centered on IAC, have spherical shape without dural

attachment or hyperostotic adjacent bone 3. Up to 100% sensitivity and specificity in modern era with

gadolinium 4. Able to accurately display size, location, depth of penetrance into

IAC (discussed later for hearing preservation surgery) 5. Heavily T2 weighted fast spin-echo series can help identify

location of facial nerve (FN) nerve with regard to the VSa. This series can also identify VS with 98–100% sensitivity and

99.5–100% specificity without gadolinium

NATuRAL HISTORY

• Determinationoftumorgrowthvariesbasedonstudy;somedefineintracanalicular tumor growth as growth to extrameatal tumor whereas others simply define tumor growth as growth in any dimension by 2 mm; most precise gauge is volumetric analysis

• DifficulttodeterminetrueVSgrowthratesaslargertumorsareintervened upon and not included in natural history studies; therefore, there is an inherent bias toward decreased growth rates

• Collecteddatainmeta-analysesshowapproximately50%ofVSgrow(data ranges from 6–73% in literature)

• MeangrowthratesinallVS1–2mm/year;thisrateincreasesto2–4 mm/year in those tumors with proven growth

• Majorityofstudiesshownorelationshipbetweengender,age,duration of symptoms, initial hearing level, and laterality and likelihood of VS growth 1. Multiple studies have shown that VS larger than 2 cm have

increased propensity to grow 2. Some evidence exists for increased growth rates of extrameatal

compared to intrameatal tumors

TREATMENT

• Overallgoalistomaintainpatientqualityoflifeandintervenewhenthe decrease in quality of life from treatment outweighs the effects of further tumor growth