1. Describe the spectrum of autoimmune ear disease.

2. Provide prompt diagnosis and treatment of patients with sudden sensorineural hearing loss (SSNHL).

3. Compare the effectiveness of oral and intratympanic steroids for the treatment of SSNHL.

4. Cite the advantages and disadvantages of the BAHA and describe a technique for its implantation.

5. Review the diagnosis of acoustic neuromas and offer some suggestions for reducing the costs associated with making this diagnosis.

Autoimmune Ear Disease (AIED)
Benjamin T. Crane, MD, PhD, Fellow in Neurotology, Johns Hopkins University School of Medicine, Baltimore, MD

Main points: sudden sensorineural hearing loss (SSNHL; within few hours to 3 days), usually in one ear and limited to ear; cause not understood, but immediate steroid therapy indicated; once weeks have elapsed, chance of recovering hearing lost; tests do not affect treatment; obtain audiogram to monitor progress and magnetic resonance imaging (MRI) to rule out acoustic neuroma

Disease spectrum: hearing loss (HL)—acute onset (<72 hr); if HL progresses over more days or months, consider noise exposure or toxicity; other symptoms—HL often associated with tinnitus and vestibular symptoms, eg, dysequilibrium, vertigo; other organs—ocular symptoms; vasculitis; upper respiratory infection (URI) immediately preceding; studies—unknown how blood tests affect prognosis or treatment; other factors—genetics; noise

Classification of AIED: rapidly progressive SNHL—no other symptoms; Cogan’s syndrome—interstitial keratitis; rule out syphilis; Susac’s syndrome—psychiatric symptoms; branch retinal artery occlusion; characteristic MRI findings; systemic autoimmune diseases—Wegner’s granulomatosis; rheumatoid arthritis; Behcet’s syndrome; systemic lupus erythematosus (SLE)

Time course of HL: often leads to diagnosis; if HL develops over years—presbycusis, history of noise exposure, family history of HL late in life; fluctuating HL—Meniere’s disease; recent hospitalization—consider aminoglycoside toxicity

Sudden SNHL: diagnosis of exclusion; concept of AIED developed in 1950s; steroid therapy started in 1970s; incidence 5 to 20 per 100,000 individuals per year; can occur at any age but most common in middle age; acute or subtle vestibular symptoms often present; hearing prognosis worse in patients with vestibular symptoms and/or advanced age; bilateral SSNHL—global problem with immune system should affect both ears, but bilateral HL rare (1%-5%); recovery rate worse than for unilateral HL; one ear may improve but not other; unilateral SSNHL—recurrence rate in same or contralateral ear very low after successful steroid treatment; study of 88 patients with 10-yr follow-up had one patient with recurrence in same ear and one with recurrence on other side

Possible causes of SSNHL: HL probably multifactorial; viral theory—some patients report having URI just before developing SSNHL; some cases with serologic evidence of acute viral infection; some histopathologic evidence of atrophic changes in temporal bone that may be typical of viral infections; some evidence in animal studies that viruses can enter inner ear; predominance of unilaterality does not support viral theory; vascular theory—supported by sudden onset and unilaterality (suggests infarction); in patients with known systemic vascular disease, incidence of SSNHL slightly higher, and bilaterality higher; animal models show histopathologic changes in cochlea with vascular occlusion; autoimmunity theory—in 1970s, evidence found of inner ear–specific T cells responding to proteins in inner ear and causing HL (not supported by unilaterality); 68 kD protein found in many (but not all) patients with SSNHL, but also in some controls; other autoimmune markers (eg, antithyroid antibodies, rheumatoid factor, anti double-stranded DNA), slightly higher in patients with SSNHL

Natural history: without treatment, some improvement seen in large fraction of patients (79% in one study); complete improvement less frequent (≈36%)

Steroid therapy: standard of care; some physicians add antiviral agent; Wilson et al (1980)—first randomized controlled trial to show benefit of steroid therapy; 67 patients with SSNHL given 12-day course of oral steroids; 32% improvement in placebo group, 61% improvement in steroid group; chance of regaining hearing doubled by prompt steroid treatment; effect of severity on natural history—patients with <40 decibel (dB) HL respond well to steroids, can improve without treatment, and achieve full recovery; those with intermediate HL (40-90 dB) have lower rate of spontaneous recovery, but steroid therapy highly effective; those with severe HL (>90 dB) have lowest rate of spontaneous recovery and do not respond well to steroids

Intratympanic (IT) steroids: advantages—avoid complications of oral steroids in patients with chronic conditions, eg, diabetes, hypertension; achieve higher steroid concentration in inner ear; disadvantage—time in inner ear short; effectiveness—shown in multiple studies; many reports of improvement with IT steroids in patients in whom oral steroids unsuccessful; animal studies show perilymph concentration of methylprednisolone order of magnitude higher with IT than with intravenous (IV) or oral steroids

Mode of delivery: operating microscope used; patient lies with affected ear up; eardrum numbed with phenol; 2 ports (superior to let air out of middle ear; inferior for delivering steroid); fluid injected should be at body temperature (if not, patient becomes slightly dizzy, as with caloric test); patient remains with ear up for ≈30 min so fluid can diffuse through round window into cochlea; fluid then removed by suction; concentration of steroid achieved in inner ear variable

Parnes study: IT steroids in 12 patients with severe HL; ≈25% had full recovery; ≈25% had partial recovery; no response in remainder

Continuous infusion into middle ear: goal to maintain steady steroid concentration in inner ear; steroid may drain through eustachian tube if patient walking around; not appreciably more effective than one-time injection

Definition of recovery: varies from study to study; degree and duration of HL influences response; criteria include— any improvement in hearing; 10 dB pure tone increase; 10% improvement in speech discrimination score; recovery of >50% of initial HL; >30 dB improvement

BAHA: The Wake Forest Experience
John S. May, MD, Associate Professor of Otolaryngology, Wake Forest University Baptist Medical Center, Winston-Salem, NC

Description of bone-anchored hearing aid (BAHA): “not a hearing aid” in usual sense because not placed in ear canal; stimulates cochlea directly by vibrating bones of skull; developed in 1970s in Sweden; approved in United States in 1996; components—titanium implant that goes into bone and flange abutment; implanted surgically and allowed to heal for 6 to 12 wk; external processor then attached; vibratory signals transmitted to cochlea; works for single-sided deafness by stimulating contralateral cochlea; implant becomes osseointegrated into skull (difficult to remove); advantages—works in patients whose ears drain whenever hearing aid present in canal; disadvantages—cost high but varies, depending on where implantation performed; can be done under local anesthesia in some centers for <$10,000; issues with healing may increase costs; types—Devino improved hearing, but newer Intenso even more effective; indications—patients with chronically draining ears; those who had previously used external bone oscillator; those with atresia or other bone fixation

Implantation: 2-stage procedure more costly; now reserved for infants and others in whom poor healing of skin around implant anticipated; one-stage procedure now typical

Technique: measure 5 to 6 cm posterior and superior to external auditory canal and mark operative site on skin; dermatome used to produce standard skin flap of consistent thickness; bevel cut under skin and remove subcutaneous tissue so no ridge present; subcutaneous tissue removed down to periosteum; periosteum then removed in area where implant to be placed; check depth and drill hole in skull; 4-mm screw for most adults, 2-mm for children; work under constant irrigation; countersink made and flange abutment attached; set torque and tap into hole; clean around post to prevent inflammation and scar formation

Healing issues: ability to detect directionality of sound varies with patient; suturing of scalp to periosteum around margins cuts down on migration of device as wound contracts during healing; make sure patient understands importance of keeping wound clean; if contracture occurs, inject triamcinolone (Kenalog) and have patient massage area; have patient return every 6 mo for first year and then yearly to ensure no development of inflammation or complications around post; speaker’s experience 60 patients; treat scar and hypertrophic tissue aggressively

Acoustic Neuromas: Cost-Effective Diagnosis
Samuel H. Selesnick, MD, Professor and Vice Chair, Department of Otorhinolaryngology, Weill Cornell Medical College, New York, NY

Incidence: fourth most common intracranial tumor, but still rare; in European countries with populations of 4 to 5 million people, incidence 12 to 18 per million annually; extrapolating to United States, 2400 to 5400 diagnosed annually in population of ≈300 million

Costs: include physician visits; audiograms and MRIs; cost of delayed treatment; cost of long-term sequelae

Diagnosis: based on characteristic symptom progression and physical findings; symptoms often do not correlate with size of tumor

Symptoms (speaker’s data from 1990s): 20% of patients with tumors ≤1 cm did not complain of HL (does not mean HL not present, but that patients complained of something else, eg, tinnitus, dizziness; tinnitus so common in United State as to be “useless” for diagnosis; vertigo—only symptom that decreases with tumor size; sensory conflict between affected ear and contralateral ear causes vertigo that leads patient to seek treatment early on; dysequilibrium— increases with tumor size, based on hypofunctioning of ipsilateral vestibular response and cerebellar compression; facial nerve symptoms—rare; hyperfunction (tick); hypofunction (weakness or paralysis); trigeminal nerve highly sensitive to compression, so 50% of patients with large tumors have facial hypesthesia (resolves quickly after tumor removed)

Stages of tumor growth: intracanalicular—vertigo, hearing loss, dizziness, dysequilibrium; fair amount of symptomatology with relatively small tumor; cisternal—considerable increase in tumor size possible without much increase in symptomatology; tumor may be barely touching brainstem and cerebellum, but no compression; brainstem compressive stage—symptoms increase; trigeminal hypesthesia; irritation of posterior petrous base (headache); fourth ventricle still patent; hydrocephalic stage—fourth ventricle compressed; nerves stretched (sometimes also on contralateral side); rapid demise in long-tract signs

Diagnostic tests: evaluate patients with asymmetric unilateral SNHL, and poor speech discrimination score; audiogram—parameters symmetrical 7% to 8% of time; not necessarily safe; follow patient and ensure return for further evaluation; 7% of patients with small tumors had normal hearing on basis of common parameters; electronystagmography (ENG)—no longer used to make diagnosis (high false-negative rate); CT with IV contrast—also has high false-negative rate; misses intracanalicular tumors; auditory brainstem response (ABR)—high false-negative rate for small tumors; MRI with gadolinium—cost $2500 at speaker’s institution

Reducing costs: decision tree—classifies patient as high, intermediate, or low probability for acoustic neuroma; difficult to determine intermediate or low probability; modification of MRI—T2-weighted fast spin-echo MRI (no gadolinium needed) reduces cost; T1-weighted MRI with gadolinium but making thick cuts also reduces cost; modification of ABR—as yet no correlation between amplitude of waveform and diagnosis of acoustic neuroma, but research promising