DEVICES, DEHISCENCE, AND TRANSTYMPANIC THERAPIES
Educational Objectives
| The goal of this program is to improve hearing and quality of life among patients with common chronic otologic
complaints. After hearing and assimilating this program, the clinician will be better able to:
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 | 1. Educate patients about options for implantable and semi-implantable hearing devices.
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| 2. Diagnose superior canal dehiscence syndrome.
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| 3. Identify candidates for intratympanic therapy with aminoglycosides or corticosteroids.
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| 4. Risk-stratify children with recurrent or chronic otitis media with effusion (OME).
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| 5. Implement guidelines for the medical and surgical management of children with recurrent or chronic
OME.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning
committee 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 faculty and planning committee reported nothing to disclose.
Acknowledgments
Dr. Slattery was recorded at the 26th Politzer Society Meeting, presented by Cleveland Clinic, and held October 13-16,
2007, in Cleveland, OH; Drs. Minor and Post were recorded at Otolaryngology Update in New York City, presented by
Weill Cornell Medical College of Cornell University, and held October 25-26, 2007, in New York, NY. The Audio-
Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.
| IMPLANTABLE HEARING DEVICES —William H. Slattery III, MD, Clinical Professor, Department of Otolaryngology,
Head and Neck Surgery, The Keck School of Medicine at the University of Southern California, and Head, Department of
Clinical Studies, House Ear Clinic, Los Angeles
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| Conventional hearing aids: amplify and transmit sound and take it to middle ear via vibratory stimulation of ossicles;
disadvantages—dissatisfaction with performance, fit, and comfort; adverse effects; poor aesthetics; social stigma; inability
to sufficiently amplify high-frequency sounds without significant feedback leads to poor sound quality; acoustic feedback
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| Implantable hearing devices: goals—improved sound quality and comfort; ease of maintenance; cosmetic acceptability;
no change in residual hearing; advantages—no feedback, obstruction, or fatigue from device use; amplification of
higher frequencies; disadvantages—surgery required (risk for complications, eg, sensorineural hearing loss [SNHL]); cost;
interference with magnetic resonance imaging (MRI); types of transducers—electromechanic; piezoelectric; electromagnetic
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| Rion: partially implantable device with piezoelectric transducer; indications—mixed hearing loss, typically with mastoid
disease (traditionally, middle ear implants indicated for SNHL; increasingly used in patients with mixed hearing loss)
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| Implex: first fully implantable system; electromagnetic transducer attaches to incus; problems—requires disarticulation
of malleus and incus to eliminate feedback through microphone; benefits—amplifies wide range of frequencies; does not
interfere with MRI; has no external components; design—3-channel signal processing unit; rechargeable battery lasts 3
to 5 yr; adjustments made by remote control; sound quality—described as “distortion-free and transparent”; patients report
better sound quality than with conventional hearing aids (but difficult to assess using available tools)
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| Envoy: fully implantable device, with piezoelectric sensor and transducers; no microphone; battery lasts 2.5 to 5 yr (no recharging);
sound waves vibrate malleus; transducer attached to malleus transmits sound to speech processor (second
transducer), which stimulates stapes; 2 mm of incus removed to prevent feedback; second-generation—new device developed
before completion of clinical trials using original device; improvements include greater gain, longer battery life
(5-8 yr), and broader range of fit
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| SoundTech: minimal surgery required; device removable, if necessary; magnetic implant placed in middle ear space; incudostapedial
joint separated; speech processor induces magnetic field, causing magnet to vibrate; benefits—improved
gain, compared to optimally-fitted hearing aids; less expensive than other implantable hearing devices
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| Vibrant Soundbridge: first implantable system approved in United States; external processor worn behind ear; device
placed through facial recess approach and attached to incus; Floating Mass Transducer placed parallel to movement of
stapes (critical); benefits—improved sound quality and quality of life (QOL), compared to conventional hearing aids, but
functional gain not significantly better; no feedback; better hearing in background noise; no change in residual hearing;
cost—$25,000 to $30,000
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| Otologics Middle Ear Transducer (MET): fully implantable device; in clinical trials; implantable microphone,
speech processor, and electromechanic transducer; remote control device used to turn unit on and off and regulate volume;
remotely rechargeable batteries; indications—SNHL; researchers looking at use in conductive hearing loss (CHL);
placement—device attached to incus in patients with SNHL, but placed on top of stapes in patients with CHL; positioning
microphone against bone results in highest benefit
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| RetroX hearing system: titanium post inserted under conchal cartilage; device placed behind ear; benefits over conventional
hearing aids—comfort (fewer problems with fit and occlusion); improved high-frequency amplification; more acceptable
cosmetically; details—4-channel speech processor; multimemory device
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| Status of devices: Rion—available only in Japan; Implex—bankrupt; Envoy—in phase 2 trials in United States;
SoundTech—available; Soundbridge—purchased by Med-El; Otologics—developing fully implantable device
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| DIAGNOSING SUPERIOR CANAL DEHISCENCE SYNDROME —Lloyd B. Minor, MD, Andelot Professor and Director,
Department of Otolaryngology—Head and Neck Surgery, Professor, Department of Biomedical Engineering, and Professor,
Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD
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| Superior canal dehiscence syndrome (SCDS): clinical manifestations—vertigo; oscillopsia; vestibular symptoms
evoked by loud noises and/or changes in intracranial or middle ear pressure (caused by, eg, coughing or sneezing); cardinal
signs—eye movements in plane of superior canal, evoked by sound or pressure; etiology—erosion of thin layer of
bone covering superior canal creates dehiscence; auditory symptoms—common (≈10% of patients have only auditory
symptoms); hypersensitivity for bone-conducted sound (hyperacusis, eg, some patients hear movement of trochlear tendon
during eye movements); autophony; audiographic and audiometric findings—presence of air-bone gap but absence of
middle ear pathology; bone-conduction thresholds may be <0 dB
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| Case series: 165 patients with confirmed diagnosis of SCDS; bilateral in 28% of cases; wide range in age at diagnosis (rare
in children); symptoms (prevalence)—sound-induced symptoms (\>50%); pressure-induced symptoms (50%); hyperacusis
(31%); chronic dysequilibrium (39%); autophony (38%); pulsatile tinnitus and positional vertigo (rare); note—patients with
patulous eustachian tube also may experience autophony (of voice and breath sounds); patients with SCDS do not have autophony
of breath sounds; signs (prevalence)—sound-evoked eye movements (45%); some patients tilt head in plane of superior
canal, in response to sound; Valsalva-evoked eye movements (36%); Hennebert’s sign (pressure-evoked eye movement;
25%)
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| Evoked eye movements: semicircular canals and eye muscles connected by neural pathways; activation of canal causes
activation of eye muscles; to elicit sound-induced response—occlude fixation (eg, by using Frenzel glasses; otherwise,
nystagmus may be suppressed); sound tone in ear; Hennebert’s sign—alternate negative and positive pressures in affected
ear; recording eye movements—technique allows recording of vestibular nystagmus and axis of rotation (but not
necessary for diagnosis)
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| Diagnosis: based on clinical judgment and diagnostic testing; computed tomography (CT)—conventional CT of temporal
bone takes images in 1-mm slices; bones <1-mm thick may appear absent; false-positive findings occur in 19% of patients;
using high-resolution CT and reformatting plane of image improves positive predictive value (but still not 100%
specific); vestibular evoked myogenic potential (VEMP)—patients with SCDS generally have abnormally low threshold
(≈75 dB vs ≈100 dB) for evoking short-latency relaxation potential in ipsilateral sternocleidomastoid muscle (vestibular
response, not auditory); audiography—low-frequency air-bone gap; no otosclerosis; acoustic reflexes present
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| Repair: use middle cranial fossa approach; selectively inactivate canal by plugging with fascia and bone; assess function
of canal using 3-dimensional eye movement testing
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| Differential diagnosis: vestibular migraine—patients may experience dysequilibrium and sound sensitivity and have
chronic problems with balance, but do not have signs and symptoms specific to SCDS; other canal dehiscences—any canal
dehiscence may cause evoked eye movements (in plane of affected canal); cholesteatoma may result in horizontal canal
fistula and associated Hennebert’s sign; Meniere’s disease (endolymphatic hydrops)—fluctuating hearing loss;
discrete episodes of vertigo
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| Etiology: developmental component—bone overlying superior canal, abnormally thin (occurs in ≈1.5% of temporal
bones, often bilaterally); traumatic or erosive component—ultimately causes dehiscence
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| IN-OFFICE TRANSTYMPANIC THERAPIES —Dr. Minor
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| History: intratympanic streptomycin first used for unilateral ablation of vestibular function in Meniere’s disease in 1952;
profound hearing loss occurred in 75% of patients; process later refined, but profound hearing loss still occurred in 10%
to 15% of patients; intratympanic aminoglycosides first used in North America in 1990s
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| Use of intratympanic gentamicin: patients with intractable vertigo caused by unilateral Meniere’s disease given single
intratympanic injection; additional injections given if vertigo remains uncontrolled or recurs; first injection initially
successful in ≈85% of cases, but recurrence common
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| Mechanism of action: intratympanic gentamicin markedly decreases (but does not abolish) function of semicircular canals;
animal studies—gentamicin abolishes afferent nerve fiber response to motion; resting discharge rate remains intact;
response—greater suppression of vertigo with decreasing vestibular function; target cells—type I (primary
target) and type II vestibular hair cells; vestibulotoxic effect seen at lower dose than cochleotoxic effect
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| Treatment of Meniere’s disease: fluctuating nature of disease hinders evaluation of treatment efficacy; options—
vestibular nerve section; endolymphatic sac surgery; intratympanic gentamicin; corticosteroids
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| Corticosteroids: decrease inflammation in ear; may increase labyrinthine circulation; indications for intratympanic
corticosteroids—idiopathic sudden SNHL; rapidly progressive SNHL; Meniere’s disease; benefits of intratympanic
delivery—avoids or reduces adverse effects associated with systemic administration; results in higher concentration in endolymph
and perilymph; achieves same improvement in hearing as systemic corticosteroids (eg, among diabetic patients
with sudden SNHL), without causing hyperglycemia; may improve pure-tone average and speech discrimination scores
among patients with sudden SNHL already treated with systemic steroids; timing—early delivery associated with greatest
gains
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| Intratympanic dexamethasone in Meniere’s disease: associated with complete relief of vertigo in 52% of patients
at 3 mo and in 43% at 6 mo; randomized, controlled trial showed no effect over placebo, but follow-up short, and
patients had advanced disease and hearing loss; complications—perforation of tympanic membrane rare, but risk increases
after irradiation of ear; burning sensation (stronger with methylprednisolone)
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| Corticosteroids for sudden SNHL: trial (in progress) comparing oral prednisone with intratympanic methylprednisolone
for treatment of sudden SNHL (patients enrolled within 14 days of onset)
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| Protocols: Meniere’s disease—for patients who have not responded to diet and diuretics, begin with single intratympanic
injection of dexamethasone (12 mg/mL); follow up in 2 to 3 wk; repeat injection at 6 to 8 wk if vertigo recurs (some patients
benefit from treatment every 3-4 mo); sudden SNHL—offer participation in trial; treat with oral corticosteroids, unless
contraindicated; consider intratympanic injection of dexamethasone (12 mg/mL), twice weekly for 2 to 3 wk (trial
protocol); retest hearing at 1 to 2 wk; initiation of treatment—many patients with SNHL complain of tinnitus; intratympanic
dexamethasone may improve tinnitus, even when initiated several months after onset
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| Injections: pharmacy must prepare fresh dexamethasone (preservatives cause intense pain; mixture lasts ≈1 wk);
procedure—make 2 small incisions (one for injection, one for ventilation); allow dexamethasone to warm to room temperature
(or, severe caloric response will result); inject dexamethasone through posterior incision
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| TYMPANOSTOMY INTUBATION AND ADENOIDECTOMY —J. Christopher Post, MD, PhD, Medical Director and
President, Center for Genomic Sciences, Allegheny-Singer Research Institute, and Director, Division of Pediatric Otolaryngology,
Allegheny General Hospital, Pittsburgh, PA
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| Otitis media (OM): most common reason for administration of antibiotics or general anesthetics in children; primary
cause of CHL in children, possibly leading to delays in language acquisition and to cognitive and behavioral problems;
risk factors—day care; passive smoking; excessive bottle feeding (breast-feeding protective); pacifier use (controversial);
positive family history
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| Myringotomy without tubes: helps relieve severe otalgia and hyperpyrexia; useful for patients with OM complicated by
facial paralysis, mastoiditis, or labyrinthitis; facilitates collection of effusion for culture (for directing therapy); especially
recommended for immunologically compromised children and as part of septic work-up in infants; reduces use of antibiotics
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| Myringotomy with tubes: most common surgical procedure performed under general anesthesia among children in
United States
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| Treatment guidelines for OM with effusion (OME): initial surgery—avoid adenoidectomy unless specifically
indicated (eg, nasal obstruction; chronic adenoiditis); repeat surgery—adenoidectomy plus myringotomy, with or without
tubes; tonsillectomy or myringotomy alone insufficient
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| Diagnosis: pneumatic otoscopy recommended as primary diagnostic tool (distinguishes OME from acute OM);
assessment—laterality; duration of effusion; presence and severity of associated symptoms; hearing, speech, and language
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| Management of OME: children at low risk for hearing and speech problems—watchful waiting for 3 mo after onset of
effusion or diagnosis; hearing assessment recommended when OME persists ≥3 mo or when language delay, learning
problems, or hearing loss suspected; repeat assessments every 3 to 6 mo until effusion resolves or surgery indicated; indications
for tympanostomy tubes—effusion \>3 mo if bilateral, \>6 mo if unilateral; recurrent acute OM (eg, 3 episodes in 6
mo; 6 episodes in 12 mo); hearing loss; anatomic changes (eg, retraction pocket; suspected cholesteatoma); eustachian
tube dysfunction; when required for drainage
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| Surgery: reasons to delay—child doing well in school; late spring or summer (fewer episodes of OM; swimming); previous
placement of myringotomy tubes did not resolve OME; family opposed to or undecided about surgery; reasons to
expedite—hearing, speech, or balance problems related to OME; poor performance in school; mental or visual problems
(ie, child more dependent on hearing); late fall or winter (unlikely child will improve); tubes resolved OME in siblings;
strong family history; benefits—improves hearing; reduces acute infections by ≈80%; facilitates diagnosis and management
of AOM; resolves associated CHL and problems with balance; reduces frequency, severity, and duration of OM episodes;
reduces incidence of long-term sequelae of chronic ear disease; risks—risk associated with general anesthesia
(low); chronic changes in tympanic membrane (eg, persistent perforations) but also caused by chronic ear disease; postoperative
extrusion of tube; persistent otorrhea; dislodged tubes may become foreign body in middle ear; growth of keratinizing
squamous epithelium into middle ear
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| Adenoidectomy: increases success rate of myringotomy with tubes (when indicated); indications—failure of first myringotomy
with tubes; nasal obstruction from adenoidal hypertrophy; sleep-disordered breathing; chronic OM; craniofacial
growth disorders; effect—may improve function of eustachian tubes; removes reservoir of bacteria; improves QOL
of child and family; reduces number of clinic visits and frequency of antibiotic use
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| Laser-assisted myringotomy (LAM): benefits—performed with local anesthesia in office setting; problems—
painful; may not achieve sufficient ventilation in young children; expensive; risk for noise damage to cochlea; no evidence
of clinical benefit over standard therapy
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Suggested Reading
Ahn JH et al: Can intratympanic dexamethasone added to systemic steroids improve hearing outcome in patients with sudden
deafness? Laryngoscope 118:279, 2008; Bird PA et al: Intratympanic versus intravenous delivery of methylprednisolone
to cochlear perilymph. Otol Neurotol 28:1124, 2007; Bodmer D et al: Long-term vertigo control in patients after
intratympanic gentamicin instillation for Ménière’s disease. Otol Neurotol 28:1140, 2007; Boleas-Aguirre MS et al:
Longitudinal results with intratympanic dexamethasone in the treatment of Ménière’s disease. Otol Neurotol 29:33, 2008;
Chow Y et al: Quality of life outcomes after ventilating tube insertion for otitis media in an Australian population. Int J
Peditr Otorhinolaryngol 71:1543, 2007; Cloutier JF et al: Superior semicircular canal dehiscence: positive predictive
value of high-resolution CT scanning. Eur Arch Otorhinolaryngol Apr 16, 2008 [Epub ahead of print]; Coates H et al: The
role of chronic infection in children with otitis media with effusion: evidence for intracellular persistence of bacteria. Otolaryngol
Head Neck Surg 138:778, 2008; Diacova S, McDonald TJ: A comparison of outcomes following tympanostomy
tube placement or conservative measures for management of otitis media with effusion. Ear Nose Throat J 86:552, 2007; Jenkins
HA et al: U.S. phase I preliminary results of the use of Otologics MET fully implantable ossicular stimulator. Otolaryngol
Head Neck Surg 137:206, 2007; Lenarz M et al: A comparative study of the audiological outcomes with Retro-X
(semi-implantable hearing aid system) and conventional open fitting hearing aids. Eur Arch Otorhinolaryngol Mar 26, 2008
[Epub ahead of print]; Roehm P et al: Gentamicin uptake in the chinchilla inner ear. Hear Res 230:43, 2007; Rosowski
JJ et al: Testing a method for quantifying the output of implantable middle ear hearing devices. Audiol Neurootol 12:265,
2007; Wilkinson EP et al: Correction of progressive hearing loss in superior canal dehiscence syndrome. Laryngoscope
118:10, 2008; Zhou G et al: Clinical and diagnostic characterization of canal dehiscence syndrome: a great otologic mimicker.
Otol Neurotol 28:920, 2007.
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