CONCEPTS IN OTOLOGY
From the Stanford Otology and Neurotology Update 2006
| CHOLESTEATOMAS: DEVELOPMENT AND RECURRENCE —Robert K. Jackler, MD, Sewall Professor and
Chairman of Otolaryngology, Professor of Neurosurgery and Surgery, Stanford University School of Medicine, Palo
Alto, CA
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| Eustachian tube (ET) dysfunction: accepted as central factor underlying formation of primary retraction-pocket cholesteatoma;
with onset of ET dysfunction—gas trapped in middle ear generates vacuum; upper flaccid portion of eardrum
draws inward to form pouch in epitympanum; keratin debris accumulates in pouch and plugs narrow orifice; as
plug expands (with or without infection) bone erodes
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| Problems with ET theory: vacuum drives only initial stage of cholesteatoma formation; in ear containing
cholesteatoma—no gas becomes trapped as epitympanum and mastoid fill with fluid, pus, and granulation tissue; mesotympanum
and ET often aerated and have good mucosa; points—presence of functioning ventilation tube anteriorly
does not stop drum from drawing inward superiorly; retraction cholesteatomas rare with anatomic obstruction of ET
(fluid fills area)
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| Mucosal traction theory of cholesteatoma formation: based on—constant migration of mucosal and squamous layers
of eardrum and middle ear lining; ability of mucosal undersurface of eardrum to contact and couple with lateral surfaces
of ossicles; tendency for mucosal migratory propulsion of conjoined layers to exert upward pull along pliable
surface containing eardrum (osseous side cannot move)
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| How mucosal traction theory explains clinical reality: tendency for cholesteatomas to form posteriorly and
superiorly— determined by superior and posterior location of ossicles; lateral surfaces of ossicles coapt with undersurface
of drum (mucosa on surface of ossicles drives activity)
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 | Retraction of eardrum and cholesteatoma formation: concept—mucus migration and coaptation draws epitympanum
inward and creates retraction pocket cholesteatoma; mucosal migration—all migratory pathways lead to mouth of
ET; if drum adhesed to ossicles, migratory motion will drag tympanic membrane along line of mucus flow; interrelationship
of cilia provides additional propulsion; mucous membrane also migrates; keratin plug forms secondarily to
pouch; bottom line—cholesteatomas drawn in from medial side, not pushed inward from lateral side; sequential
adhesion—series of mucosal bands could adhere and pull into epitympanum also
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| Strong association between hypopneumatization and cholesteatoma formation: pneumatization of temporal bones—
minimal at birth; normal adult air cell system forms as pouches of rapidly dividing mucosal buds invade marrow-
filled bone during infancy; hypopneumatization—can develop when normal pneumatization delayed until child 5
or 6 yr of age; occurs as calcified mastoid (now filled with fatty marrow) rejects entry of migrating mucous membrane;
in presence of blockage, hyperactive mucosal migration could drive cholesteatoma formation; concept supported
by—tendency of cholesteatomas to follow pathway of normal pneumatization; presence of acquired
cholesteatomas in 6- to 10-yr-old children; relative absence of acquired cholesteatomas in younger children
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| Why some patients develop cholesteatomas with retraction and other patients develop atelectasis: migratory
pattern—in some ears, may have more rapid or vigorous migration; in other ears, may not generate net motion; mucin
characteristics—thin mucus lubricates abutting membrane surfaces and allows them to glide by each other; viscous
sticky mucus causes adherence of coapted surfaces and couples migratory motion
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| Mucosal traction theory: cholesteatoma—fundamentally mucosal disease; proximity of ossicles essential to pathogenesis;
mucosal traction explains—how cholesteatoma growth can be driven into nonaerated mucosal spaces, eg,
epitympanum, antrum; why functioning pressure equalization (PE) tubes do not prevent cholesteatoma recurrence;
why PE tube placement in children may not prevent cholesteatoma formation (most teenagers or young adults who
present with cholesteatomas were intubated in childhood; Irish data suggest intubation does not change incidence of
cholesteatoma); why cholesteatomas limited to posterior and superior quadrants (presence of ossicles); why some patients
get atelectasis with collapse of tympanum while others get pockets without atelectasis; why anatomic obstruction
of ET typically does not lead to cholesteatoma
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| ACOUSTIC NEUROMAS: COST-EFFECTIVE DIAGNOSIS —Samuel A. Selesnick, MD, Professor and Vice Chair,
Department of Otolaryngology, Weill Medical College of Cornell University, New York, NY
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| Acoustic neuroma (AN): rare; best diagnosed when small; progresses to cerebellum, brainstem, mastoid, and vestibular
apparatus; management costs include—staffing and equipment required for diagnosis; management of problems associated
with delayed treatment; point—symptom progression correlates with but does not always parallel physical
findings; stages of symptom progression—intracanalicular (hearing loss, tinnitus, vertigo, and early eighth nerve
symptoms); cisternal (quiescent; growth rate does not translate into increased symptomatology; no brainstem compression);
brainstem compressive (fifth nerve symptoms develop, eg, facial hypesthesia, headache with dural irritation);
hydrocephalic (full-blown symptomatology and long-tract signs; rapid deterioration and death)
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| Diagnosis of AN: goals of diagnosis—cost-effectiveness; efficiency; patient comfort; minimization of risk; key diagnostic
tools—physical examination; patient history
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| Audiometric diagnosis: includes speech reception thresholds (SRT), speech discrimination score (SDS), and high-frequency
hearing loss; problems—many patients atypical, (eg, hearing symmetric or normal) and present with other
symptoms, eg, tinnitus, balance disorders, facial hypesthesia; cost prohibits screening
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| Archaic tests: electronystagmography (ENG; high false-negative rate; not cost-effective or time-effective for evaluating
patient for AN); auditory brainstem response (ABR; false-negative rate [≈33%] unacceptable for managing
young patients who can hear and in whom intervention can achieve favorable outcome); computed tomography
(CT) with intravenous (IV) contrast (poor test; false-negative rate 37%; contraindicated in patients with pacemakers);
pneumoencephalographic CT—good test (but painful)
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| Problems with: magnetic resonance imaging (MRI)—expensive; usually negative; diagnostic algorithms—difficult
to determine where to place patient in algorithm; clinical suspicion high in patient with unilateral sensorineural
hearing loss (SNHL) and facial hypesthesia; system less useful for unilateral tinnitus, aural fullness, dizziness, and
dysequilibrium
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| Cost-effective modalities for identifying AN: MRI with high-resolution fast spin echo T2-weighted sequence in internal
auditory canal (IAC)—advantages (low cost; facilitates visualization of cochlear and inferior vestibular nerves);
gray mass without cerebrospinal fluid (CSF) suggestive of lesion in canal; does not address other causes of SNHL;
stacked ABR—increases diagnostic sensitivity by aligning waveforms
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| Issues in management of AN: macroeconomic—diagnosis (cost of special testing vs cost of follow-up if early diagnosis
not made); treatment (increased expense of managing larger tumors); factors affecting society (long-term health
care services, unproductive citizens, and medicolegal costs); philosophic debate focusing on—whether wealth of society
should determine patient care; whether shrinking health care dollar would be better spent on prevalent preventable
diseases (eg, hypertension)
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| ACOUSTIC NEUROMAS: SELECTIVE MANAGEMENT —Dr. Jackler
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| Observation: sensible option for—patient with small tumor; elderly patient; patient with long symptomatic history;
points—clinical cost of delayed management minimal; many patients treated by surgery and radiotherapy would have
done well with observation alone
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| Surgery: definitive management; disadvantages include—postoperative downtime; facial neuropathy with microsurgery;
headaches; leaks of spinal fluid
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| Microsurgery: choose approach most likely to preserve hearing; selection often requires balancing risks vs benefits;
translabyrinthine approach—workhorse procedure for patient with any sized tumor and poor hearing; used to manage
patients with large tumors and good hearing (hearing cannot be salvaged); retrosigmoid approach—indicated for
nonacoustic tumors of cerebellopontine angle, some meningiomas and epidermoids, and select candidates for hearing
preservation; used to treat tumors with limited involvement of IAC; limited success with larger lesions; middle fossa
approach—best for preserving hearing, ie, favored for managing tumors ≤15 mm in angle; associated with facial
nerve problems when used to manage larger tumors
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| Stereotactic radiation therapy: advantages—easy to perform; patients drive themselves home after surgery; minimal
interruption of life; better hearing results after treatment of large tumors; better facial function if lesion does not recur;
lower morbidity; disadvantages—persistence of tumor; risk for secondary oncogenesis; dysequilibrium;
technology—CyberKnife (frameless; dose can be fractionated; 3 or 4 sessions may improve hearing outcome);
approach—maximizes radiation dose to tumor; minimizes collateral dose to surrounding structures; points—loss of
central contrast and stabilization of tumor considered favorable outcome; tumor does not disappear (central necrosis
and shrinkage may be visible at 1 yr post-therapy); many AN specialists improve comprehensive patient care by becoming
proficient at observation protocols, radiation therapy, and microsurgery
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| Issues in stereotactic radiation therapy: using current dose regimens—recurrence rate 5% to 10%; tumor growth rare
in patients who remain stable 6 to 7 yr post-therapy; impact of approach on—natural history of AN (over 3-yr interval,
radiation can decrease tumor growth rate by ≈40%); facial nerve (delivering <25 Gy to margin virtually eliminates
severe neuropathy); hearing (with contemporary dosing, 50%-60% of patients maintain functional hearing 5 yr post-
therapy; two thirds of patients with neurofibromatosis type 2 [NF2] lose hearing within few years after therapy); large
tumors (irradiation contraindicated for tumors >2 cm); points—tumor bruised by radiation, so swells during first year
post-therapy; over time, lesion shrinks and stabilizes; salvage if—tumor continues to grow after irradiation (shell out
tumor without dissecting facial nerve; irradiated facial nerve lacks recuperative ability of healthy nerve); residual tumor
continues to grow after surgery (radiation salvage of surgical failure works well; surgical salvage of radiation failure
less effective); problems with stereotactic radiation of benign tumor—risk for malignancy (latency period 4-8 yr;
lesions lethal); sequelae include hydrocephalus, ruptured IAC aneurysm, accelerated vertebrobasilar atherosclerosis
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| Combined approach to saving facial nerve in patient with large AN: should enhance functional outcomes;
approach—shell out lesion; leave rind; never engage plane of facial nerve; should rind bulk up, administer supplemental
radiation to focused target of disease growth
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| BENIGN PAROXYSMAL POSITIONAL VERTIGO (BPPV): THE LATEST SPIN —Sumit K. Agrawal, MD, Department
of Otolaryngology–Head and Neck Surgery, Stanford University School of Medicine, Palo Alto, CA
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| Benign paroxysmal positional vertigo: most common vestibular disorder; canal orientation—horizontal canal (tilts
upward 30° from horizontal; ampullated end superior; nonampullated end dependent); posterior canal (tilted 45° to
midline along petrous face; parallel to contralateral superior canal; posterior and superior canals work in conjunction);
impact of endolymph flow—in posterior canal, ampullopetal flow inhibitory, while ampullofugal flow excitatory;
in horizontal canals, flow effects reversed; ocular movement—horizontal canal (horizontal nystagmus with
stimulation of medial and lateral rectus muscles); posterior canal (rotatory nystagmus with stimulation of ipsilateral
superior oblique muscle and contralateral inferior rectus muscle); models for—posterior semicircular canal BPPV
(seen in >90% of cases; majority caused by canalithiasis; free-floating crystals become trapped at ampullated end of
posterior canal and return to utricle by going up and around nonampullated end); horizontal canal BPPV (more
likely caused by cupulolithiasis; gravity alone can return particles to utricles)
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| Free-floating particles and nystagmus: for patient to become symptomatic, particles must form critical mass; latency of
nystagmus occurs as particles—fall in canal and overcome resistance of endolymph and cupula; cause cupular displacement;
torsional nystagmus associated with ampullofugal flow in posterior canal and stimulation of canal—duration
limited; once particles settle, drag from endolymph eliminated and stimulation stops; once patient returns to
seated position, particles return to ampullated end of canal and reverse flow; reverse nystagmus develops;
fatigability—occurs as particles become dispersed along canal and no longer create flow; point—data suggest particle
size determines magnitude of response to Dix-Hallpike maneuver and canalith repositioning maneuvers
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| Facts about BPPV: incidence—may be more common in women (men and women probably have equal incidence of
post-traumatic BPPV); ≤9% of elderly individuals may have BPPV (because symptomatology vague, perform Dix-
Hallpike maneuver on any patient with vestibular complaint); etiology—most patients have idiopathic disease; secondary
BPPV most commonly associated with head trauma, vestibular neuronitis, migraine headaches, Meniere’s disease,
and otologic surgery (test any patient with preexisting syndrome who experiences change in dizziness)
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| Diagnosis: history—short bursts of rotatory vertigo with specific head movement; in some studies, ≤50% of patients
describe floating sensation without typical history; can include sensations patient feels when rolling in bed (symptoms
on side with affected ear); posterior canal BPPV—Dix-Hallpike maneuver (key diagnostic tool; turn head 45°
to bring posterior canal into vertical plane; extend head 30°); nystagmus (preceded by latent period; occurs with superior
pole beating toward downward ear; lasts 20-30 sec; associated with vertigo; monitored by observing conjunctiva
and blood vessels of eye; reverses direction once patient gets up)
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| Lateral canal BPPV: diagnosis—made using lateral head turns; complicated because patient can have cupulolithiasis
or canalithiasis; depends on whether patient has geotropic or ageotropic nystagmus and on which side has stronger
nystagmus (ie, head turned to left or to right; eg, patient with cupulolithiasis on left side has stronger ageotropic nystagmus
on right side); canalithiasis in horizontal canal—particles usually settle in most dependent portion of canal
(opposite cupula near nonampullated end of canal); geotropic nystagmus occurs as head is turned, eg, for left
canalithiasis, patient has stronger geotropic nystagmus on left side
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| Management maneuver: based on Epley canalith repositioning maneuver; approach—use Dix-Hallpike maneuver to
elicit nystagmus (if positive, convert directly to particle repositioning maneuver); once nystagmus settles, perform repositioning
maneuver on opposite side; keep patient’s head extended 30°; rotate patient 180°; maneuver should elicit
another burst of nystagmus in same direction as initial nystagmus (if nystagmus reverses, procedure must be repeated);
if patient has—ipsilateral nystagmus, success rate >90%; reversal of nystagmus, success rate <10%)
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| Maneuver options for managing lateral canal BPPV: prolonged position (patient lies for 12 hr with affected ear upward);
barrel roll (patient rolls 360° at 90° increments away from affected ear); log roll (patient’s head turned 270°; indicated
for individuals who cannot lie on side or stomach
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| Surgery: indicated when repositioning maneuvers ineffective and BPPV incapacitating; singular neurectomy—7% risk
of SNHL; technically challenging; posterior semicircular canal occlusion—performed on severely incapacitated patients;
results good; postoperative hearing loss and imbalance tend to resolve
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Suggested Reading
Agrawal SK et al: Diagnosis and management of benign paroxysmal positional vertigo (BPPV). CMAJ 169:681, 2003;
Arts HA et al: Hearing preservation and facial nerve outcomes in vestibular schwannoma surgery: results using the
middle cranial fossa approach. Otol Neurotol 27:234, 2006; Ciric I et al: Suboccipital retrosigmoid approach for removing
vestibular schwannomas: facial nerve function and hearing preservation. Neurosurgery 56:560, 2005; Don M et al:
The stacked ABR: a sensitive and specific screening tool for detecting small acoustic tumors. Audiol Neurootol 10:274,
2005; Dornelles C et al: Histologic description of acquired cholesteatomas: comparison between children and adults.
Rev Bras Otorrinolaringol 72:641, 2006; Jackler RK: The surgical anatomy of cholesteatoma. Otolaryngol Clin North
Am 22:883, 1989; Roberts RA et al: Treatment of benign paroxysmal positional vertigo: necessity of postmaneuver patient
restrictions. J Am Acad Audiol 16:357, 2005.
Educational Objectives
| The goal of this program is to clarify current concepts in the management of common otologic diseases. After hearing
and assimilating this program, the clinician will be better able to:
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| 1. Describe new concepts in the development and recurrence of cholesteatoma.
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| 2. Develop a more cost-effective approach to the diagnosis of acoustic neuromas.
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| 3. Assess available options for treating acoustic neuromas.
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| 4. Avoid potential complications associated with radiation therapy for acoustic neuromas
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| 5. Implement appropriate techniques for managing benign paroxysmal positional vertigo (BPPV).
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant
financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified
conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business
or commercial interest. For this program, the following has been disclosed: Dr. Selesnick is affiliated with
Medtronic Xomed, Inc.
Acknowledgements
Drs. Agrawal, Jackson, and Selesnick gave their scientific lectures at Stanford Otology and Neurotology Update 2006,
presented November 2-4, 2006, in San Francisco, CA, by Stanford University School of Medicine. The Audio-Digest
Foundation thanks the speakers and the sponsor for their cooperation in the production of this program.
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