OBSERVATIONS IN OTOLOGY
| RECENT ADVANCES IN CHRONIC EAR SURGERY —Richard J. Wiet, MD, Professor of Clinical Otolaryngology and
Neurosurgery, Department of Otolaryngology–Head and Neck Surgery, and Director, Neurotology/Skull Base Surgery Fellowship,
Northwestern University Medical School, Hinsdale, IL
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| Classification of ear disease: tubotympanic—only mucoperiosteum affected; atticoantral—associated with more
severe clinical outcomes; includes cholesteatomas of pars flaccida or pars tensa
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| Evaluation: history; otologic and micro-otoscopic examinations; audiologic evaluation; stapedial reflex testing (useful
for diagnosis of superior canal dehiscence); imaging —radiographic examination for some patients (eg, revision surgery,
suspected fistula or progressive rarefying osteitis); magnetic resonance imaging (MRI) or magnetic resonance angiography
(MRA) rarely used, but recommended when severe disease suspected (eg, pulsations after placement of PE tube may
indicate meningoencephalocele)
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| Complicating factors: poor aeration; persistent disease; problems with tympanic membrane or ossicular coupling; eustachian
tube dysfunction most common cause of failure after ossiculoplasty; persistent mucosal disease may require
staged surgical procedures; degree of pneumatization of mastoid may affect surgical approach (wall-up or wall-down);
aeration—placing PE tubes may improve hearing in patient with chronic ear disease without erosive changes; persistent
disease—refractory otitis media (OM) associated with presence of bacterial biofilm may require mastoid surgery; canal-
wall-down mastoidectomy may decrease rate of residual cholesteatoma (compared to wall-up approach) in select patients;
tympanic membrane perforations—size of tear correlates with degree of conductive hearing loss (CHL); volume
of middle ear inversely affects transmission of sound; ossicular chain—canal wall-up and wall-down procedures have
similar effects on hearing as long as ossicular structures comparable; small changes in position of ossicles significantly
affect mechanics; classic high-frequency CHL occurs when stapes partially fixed but stapedial reflex present
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| Ossicular implants: autographs and allographs principally used; categories—passive (biocompatible but inert); active;
partial ossicular reconstruction prosthesis (PORP)—bone substitute (eg, OtoMimix) may be used to fix in place; reconstruction
of ossicle possible if segment remains; total ossicular reconstruction prosthesis (TORP)—associated with
lower closure rates of air-bone gap and worse outcomes; shoes developed to maintain position in oval window and to prevent
slippage; ossicular glue often used to fix proximal end; tension (exerted on surrounding structures) critical; long-
term outcomes—study showed 59% of patients with PORPs and 30% of those with TORPs had hearing loss of <20 dB at
5 yr; poor results attributed to hostile environment of middle ear and persistent recurrent disease
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| Emerging technologies: active implant with intraoperative hearing assessment; hearing may be stimulated by placing
implant on round window (Colletti, 2006); type IV tympanoplasty (aeration critical to success; no implant required)
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| INNER EAR MALFORMATIONS —Robert K. Jackler, MD, Professor and Chair, Department of Otolaryngology–Head
and Neck Surgery, Stanford University Medical Center, Stanford, CA
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| Embryology: cochlea, vestibular system, and endolymphatic aqueduct form during first trimester; exposure to teratogens
may cause malformations; cochlea begins to curl in week 6; sensory epithelium of organ of Corti forms during third trimester;
maternal exposure to streptomycin in third trimester increases risk of damaging hair cells of fetus; exposure to
thalidomide in first trimester may cause profound malformations of inner ear
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| Congenital malformations: computed tomography (CT) and high-resolution MRI only identify malformations that involve
bone; diagnosis of malformations of the membranous labyrinth require postmortem histologic evaluation; 5% to
10% of children with early hearing loss have abnormalities discernible by CT or MRI; remainder assumed to have membranous
deformities; although development of inner ear is entirely separate from that of middle ear, some patients have
abnormalities that affect both; “Mondini’s dysplasia”—originally referred to cochleae with 1.5 turns, but later used to
refer to any dysplasia of inner ear; careful description important, because pattern of dysplasia affects prognosis and risk
for complications
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| Imaging: high-resolution MRI suitable for older children and adults; CT preferred in young children (general anesthesia
not required)
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| Cochlear malformations: cochlear aplasia—complete failure of formation of inner ear; otic capsule absent;
hypoplasia—stunted size and coiling of cochlea; incomplete partition—cochlea smaller than normal; incomplete architecture
of interscalar septum; common cavity—vestibule appears enlarged, confluent with cochlear anlage; relative
incidence—incomplete partition most common, followed by common cavity, hypoplasia, aplasia, and complete labyrinthine
aplasia (least common)
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| Semicircular canal (SCC): embryology—semicircular evagination forms; central portion adheres, leaving peripheral
ring; failure of adherence results in dysplastic lateral canal; malformations—isolated dysplasia of lateral SCC most common
(appears short and broad on radiograph); multiple dysplastic canals and complete aplasia also occur
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| Vestibular aqueduct enlargement: most common radiographically detectable malformation in children with hearing
loss; associated with Pendred’s syndrome, but also occurs sporadically; associated findings—vestibule often enlarged;
modiolus may be dehiscent; cerebrospinal fluid (CSF) pressure present in inner ear; pseudo-CHL may occur; surgical
complications—patients at high risk for CSF “gusher” with stapedectomy; endolymphatic sac surgery associated with
poor outcomes; no role for surgery at this time
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| Cochlear aqueduct enlargement: formerly purported to cause CSF gushers and leaks (questioned by speaker); anatomic
features—narrow channel through otic capsule; wide external aperture; folded meshwork of fibrous tissue runs
through lumen; misinterpretations of radiographic findings have led to misdiagnosis
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| Internal auditory canal (IAC): large IAC does not correlate independently with hearing, but narrow IAC associated
with poor outcome after cochlear implantation
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| CSF leaks: CT recommended for children with meningitis and hearing loss or multiple bouts of meningitis (inner ear
anomalies increase risk); leaks usually associated with deafness; importance of preoperative imaging—multiple malformations
may occur and increase risk for CSF gusher with surgery
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| Cochlear implants: outcomes often good because neural function remains partially intact; device may follow unusual
path in malformed cochlea (eg, may penetrate posterior fossa), so CT recommended to assess position before activating
implant
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| MENIERE’S DISEASE: AN EVIDENCE-BASED APPROACH —Anh Nguyen-Huynh, MD, Assistant Professor, Department
of Otolaryngology, Oregon Health Science Center, Portland
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| Background: characteristics—fluctuating hearing loss; episodic vertigo, tinnitus, and aural fullness; etiology—excess
production of endolymph causes scala media to balloon, eventually rupturing Reissner’s membrane
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| Endolymphatic hydrops and Ménière’s disease: formerly, endolymphatic hydrops considered responsible for
symptoms of Ménière’s disease; study used database from Massachusetts Eye and Ear Infirmary to compare patient histories
(ie, clinical evidence of Ménière’s disease) with findings of histopathology slides (ie, histologic evidence of endolymphatic
hydrops); although all patients with Ménière’s disease had hydrops, not all patients with hydrops had
Ménière’s disease (some had no vestibular symptoms); sensorineural hearing loss (SNHL) always accompanies endolymphatic
hydrops; conclusion—endolymphatic hydrops does not cause all symptoms of Meniere’s disease, but constitutes
histopathologic marker
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| Definition: inconsistently used; “definite” criteria—episodes of vertigo last \>20 min; SNHL may fluctuate; other causes
of hearing loss and vertigo ruled out; “certain” criteria—histopathologic characteristics (post mortem); function—
grading system developed by American Academy of Otolaryngology–Head and Neck Surgery; research implications—
because disease has fluctuating nature and potential for spontaneous resolution, studies evaluating treatment efficacy
must have follow-up ≥2 yr; patients’ pre-treatment symptoms followed for 6 mo and compared with symptoms during 6-
mo period at end of 2 yr
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| Diet: low sodium diet often used as first-line therapy, but not scientifically validated; sodium restricted to 1500 mg/day;
avoidance of caffeine, alcohol, and tobacco recommended
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| Medical therapy: various classes of medication used; review shows improvement of 60% to 80%; high placebo effect
suspected; only diuretics and β-histine (not available in United States) control vertigo effectively over long term; none
shown to influence progression of SNHL; small, double-blind, placebo-controlled cross-over study found thiazide diuretic
associated with improvement of vertigo, but not hearing or tinnitus
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| Device therapy: studies show mixed results; controlled study (which accounted for effect of myringotomy tubes)
showed improvement in function but not in symptoms
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| Vestibular ablation: studies with intratympanic (IT) dexamethasone poorly designed, so conclusions about efficacy not
possible; more evidence for IT gentamicin; meta-analysis found titration approach (amount of gentamicin based on
symptom severity) most effective; 82% of patients achieved complete control and 96% had substantial improvement of
vertigo; low-dose approach least effective; high-dose approach associated with high risk for SNHL; degree of vestibular
ablation not correlated with symptomatic improvement; systemic aminoglycosides—especially effective in patients with
bilateral condition, but associated with high rate of SNHL and disequilibrium
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| Surgical treatment: endolymphatic sac surgery—success rate (70%) same as with sham control (mastoidectomy without
sac surgery); long-term follow-up shows some SNHL; vestibular neurectomy—large series showed complete control
of vertigo in 85% of patients and substantial improvement in 92%; hearing largely preserved; labyrinthectomy—gold
standard; success rate nearly 100%, but hearing sacrificed; risk for bilateral involvement (estimated at 15% to 30%) may
influence decision to sacrifice hearing
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| SUPERIOR SEMICIRUCLAR CANAL DEHISCENCE SYNDROME —Anthony Mikulec, Assistant Professor and Chief,
Otologic and Neurotologic Surgery, St. Louis University School of Medicine, St. Louis, MO
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| Case: male, 40 yr of age, with 18-mo history of sensitivity to pressure and sound on left side, causing tilting of visual field;
symptoms precipitated by straining, loud noise, driving, and running; no significant findings on electronystagmography
(ENG), electroencephalography (EEG), or MRI; history includes 4-min loss of consciousness from slip and fall several
years earlier; physical examination—external auditory canals and tympanic membranes normal; Weber midline; positive
Rinne test (bilateral); positive Hennebert’s sign (left side) with torsional deviation of eyes and sensation of body tilt;
acoustic stimuli at 110 dB and 1000 Hz yield same result on left side; no other significant findings; testing—vestibular
evoked myogenic potential (VEMP) shows decreased threshold; normal auditory brainstem response (ABR); CT of temporal
bone—Poschl view reveals fistula between superior semicircular canal and overlying dura; Stenvers view shows
dehiscence; treatment—left-sided middle fossa craniotomy; dehiscence plugged with bone wax and temporalis fascia
overlay; outcome—complete resolution of symptoms by 1 mo; hearing and facial nerve function preserved
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| Superior semicircular canal dehiscence (SSCD): dehiscence creates “third mobile window” in otic capsule; superior
canal—thickness of overlying bone increases during first year of life; thickness and degree of pneumatization
vary; proposed etiology—genetic factors likely have role in development of thin overlying bone; traumatic inciting
event disrupts bone; elevated intracranial pressure erodes bone over time; clinical presentation—chronic dysequilibrium;
destabilization evoked more commonly by sound than pressure, resulting in vertical and torsional nystagmus; excitation
of superior canal may occur with loud sounds (ie, Tullio), fistula test, positive pneumatoscopy, or nose-blowing;
pathophysiology—increased intracranial pressure causes endolymph to move through dehiscence down both limbs of superior
canal, activating membranaceous ampulla
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| Audiologic evaluation: audiometry; VEMP; ENG; stapedial reflex test; audiometric findings—supranormal bone
threshold (audiologist must check for hearing better than 0 dB); mild-to-moderate CHL (may mimic otosclerosis); discrimination
generally normal; VEMP—true otosclerosis or CHL associated with chronic ear disease elevates threshold;
SSCD depresses threshold (regardless of degree of low-frequency CHL)
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| Imaging: CT including Poschl and Stenvers views critical for diagnosis; false positives may occur because of inability to
distinguish bone thinner than 0.1 mm
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| Diagnosis: chronic dysequilibrium; vestibular or visual symptoms evoked by acute pressure or sound; SSCD visible on
CT; depressed VEMP threshold
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| Treatment: avoiding inciting stimuli often sufficient; PE tubes or ear plugs may help; surgery—middle fossa approach
provides easiest exposure; concurrent mastoidectomy aids identification of SSCD; suction typically sufficient for retraction;
plugging material (eg, bone wax, bone dust with fibrin glue) must fill both limbs of canal; outcomes—small case
series showed resolution of Tullio, Hennebert, and autophony; chronic imbalance and CHL resolved or improved in most
patients; complications included high-frequency SNHL and vestibular dysfunction
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| Bilateral disease: preoperative bilateral assessment of vestibular function recommended; up to 33% of patients have radiologic
evidence of bilateral disease; ear with more severe symptoms treated first
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| SSCD and hearing: SSCD may present as unexplained CHL without vestibular symptoms; pressure leakage through
dehiscence and decreased air conduction results in low-frequency CHL; bone conduction—presence of third mobile
window lowers impedance of system (less energy required to create pressure difference between scala vestibuli and
scala tympani); reduced resistance to vibration results in supernormal bone conduction at low frequencies; note—size
of dehiscence not correlated with severity of symptoms
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 | Case: woman, 27 yr of age, with 3-yr history of right-sided CHL without vertigo or imbalance; no audiometric changes
after stapedectomy; VEMP threshold reduced on right side, normal on left; CT revealed dehiscence
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| Evidence: surgical repair generally eliminates CHL; no middle ear abnormalities identified during surgery; diagnostic
tests support causal relationship between SSCD and CHL
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| Unanswered questions: details of etiology; role of genetics; symptom distribution; incidence (probably ≈1%); relationship
between SSCD and posterior semicircular canal dehiscence
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Suggested Reading
Carey JP et al: Semicircular canal function before and after surgery for superior canal dehiscence. Otol Neurotol
28:356, 2007; Chia SH et al: Intratympanic gentamicin therapy for Ménière’s disease: a meta-analysis. Otol Neurotol
25:544, 2004; Colletti V et al: Treatment of mixed hearing losses via implantation of a vibratory transducer on the round
window. Int J Audiol 45:600, 2006; Helling K et al: Treatment of Ménière’s disease by low-dosage intratympanic gentamicin
application: effect on otolith function. Laryngoscope Sep 2007 [Epub ahead of print]; Mehta RP et al: Determinants
of hearing loss in perforations of the tympanic membrane. Otol Neurotol 27:136, 2006; Parner ET et al: Hearing
loss diagnosis followed by meningitis in Danish children, 1995-2004. Otolaryngol Head Neck Surg 136:428, 2007; Post
JC et al: The role of biofilms in otolaryngologic infections: update 2007. Curr Opin Otolaryngol Head Neck Surg 15:347,
2007; Van Wermeskerken GK et al: Audiological performance after cochlear implantation: a 2-year follow-up in
children with inner ear malformations. Acta Otolaryngol 127:252, 2007; Whittemore KR et al: Acoustic mechanisms:
canal wall-up versus canal wall-down mastoidectomy. Otolaryngol Head Neck Surg 118:751, 1998; Yung M: Long-term
results of ossiculoplasty: reasons for surgical failure. Otol Neurotol 27:20, 2006; Zhou G et al: Clinical and diagnostic
characterization of canal dehiscence syndrome: a great otologic mimicker. Otol Neurotol 28:920, Aug 2007.
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Educational Objectives
| The goal of this program is to improve outcomes of corrective surgery of the middle and inner ear. After hearing and
assimilating this program, the clinician will be better able to:
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| 1. Identify factors associated with poor outcomes after ossiculoplasty.
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| 2. Describe congenital malformations of the inner ear.
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| 3. Reduce risk for cerebrospinal fluid “gushers” during inner ear surgery.
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| 4. Use an evidence-based approach to management of Ménière’s disease.
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| 5. Diagnose and treat patients with superior semicircular canal dehiscence syndrome.
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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. Wiet receives an honorarium from
Medtronic for the design and development of surgical instruments.
Acknowledgments
Dr. Wiet was recorded at the 2006-2007 lecture series, sponsored by the Chicago Laryngological and Otological Society,
and held March 5, 2007, in Chicago, IL; Drs. Jackler, Nguyen-Huynh, and Mikulec were recorded at Stanford
Otology and Neurotology Update 2006, sponsored by the Department of Otolaryngology–Head and Neck Surgery,
Stanford University School of Medicine, and held November 2-4, 2006, in San Francisco, CA. The Audio-Digest
Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.
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