otology, neurotology, and skull base surgery · otology, neurotology, and skull base surgery...
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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