Speakers
Hamid Djalilian, MD, Professor of Otolaryngology and Biomedical Engineering, and Director of Otology Neurotology and Skull Base Surgery, University of California, Irvine, School of Medicine
Summary
Introduction: sudden hearing loss is an uncommon condition, with a yearly incidence of 5 to 20 in 100,000 individuals; for the purpose of clinical studies, defined as hearing loss of ≥ 30 dB over ≥ 3 contiguous frequencies, with loss occurring over < 72 hr; ≈ 30% of patients recover their hearing over time without treatment; most patients present with unilateral hearing loss (rarely bilateral)
Assessment of bilateral sudden hearing loss: the cause of bilateral sudden hearing loss is assumed to be a systemic disorder until proven otherwise; in such cases, a thorough diagnostic workup to rule out systemic diseases such as autoimmune conditions is essential and may include assessing blood glucose levels, cholesterol levels (to rule out familial hypercholesterolemia) and complete blood count (CBC; to check for hypercoagulable states and high platelet or red cell counts); other assessments, such as antineutrophil cytoplasmic antibodies (ANCA) test to check for granulomatosis with polyangiitis (GPA), erythrocyte sedimentation rate, antinuclear antibodies, C-reactive protein, and rheumatoid factor tests, also can be done; infectious etiology should be ruled out using a rapid plasmin reagin test for syphilis, tests for HIV, measurement of Lyme disease antibody titers, and an interferon γ-release assay for tuberculosis (eg, QuantiFERON Gold); the diagnostic workup must be completed and the etiology identified before oral steroids are started, as this treatment affects the autoimmune lapse; most affected patients awaken from sleep with hearing loss, along with other symptoms (eg, aural fullness, tinnitus, vertigo)
Differential diagnosis: infections such as syphilis, Lyme disease, tuberculosis, mumps, or cytomegalovirus (CMV); autoimmune conditions such as Cogan syndrome, systemic lupus erythematosus), or GPA; conditions such as perilymph fistula, significant acoustic trauma, temporal bone fracture, and neoplasms involving the cerebellopontine angle (primary or metastatic); ototoxic drugs, such as aminoglycosides and aspirin (sudden hearing loss is reversible when caused by aspirin); vascular diseases (eg, sickle cell disease, thromboembolism, macroglobulinemia); congenital disorders, including enlarged vestibular aqueduct and Mondini dysplasia; while sudden hearing loss is most often attributed to viral disease, there is little evidence to support this belief; exceptions are cases caused by congenital CMV with later activation or hearing loss associated with mumps; past research suggested that a large percentage of patients with sudden hearing loss had a viral upper respiratory infection within 6 wk of the onset of symptoms; however, in some locations and during colder seasons, such infections are highly prevalent, so their link to causation is not meaningful
Literature review (etiology of sudden hearing loss): Perlman (1959) showed that occlusion of the labyrinthine artery in a guinea pig results in loss of cochlear microphonics within 60 sec; labyrinthine artery occlusion was historically believed to be the only vascular etiology, but in most patients, fluid extravasation within the cochlea or vasodilation or vasospasm of the artery is a more likely cause; a large study in Korea found that patients with migraine are 50% more likely to develop sudden hearing loss, compared with those without migraine; Chu et al found that the likelihood of hearing loss was 80% higher in migraineurs than in those without migraine history; in 1987, Jenkins et al reported a case of recurrent sudden hearing loss associated with episodes of migraine headache; another recent study that reviewed the National Health and Nutrition Examination Survey (NHANES) database shows that subjective hearing loss and tinnitus are more common in patients with migraine; a series of studies by Nuttall shows that stimulation of the ophthalmic branch of the trigeminal nerve leads to fluid extravasation in the cochlea within 60 min, likely because of changes in vascular permeability in the cochlea; permeability increased with increased stimulation
Migraine and sudden hearing loss: sudden hearing loss is seen in only a small portion of patients with migraine, possibly reflecting genetic differences; a small proportion of patients with migraines develop cochlear migraine; cochlear migraine — characterized by hearing loss, sometimes recurrent, usually in the lower frequency range; usually not accompanied by dizziness; patients often have a history of motion intolerance and may have a history of neck stiffness or headache; in the study based on the NHANES database, neck stiffness was 4 times more common in patients with migraine than in patients with no such history
Migraine and endolymphatic hydrops (ELH): a study using high-resolution, delayed, gadolinium-enhanced magnetic resonance imaging (MRI) of the inner ear showed that, in patients who had sudden hearing loss related to migraine, the appearance of the cochlea and vestibule resembles that in ELH; this finding suggests that migraine may be a cause of ELH, which may manifest as hearing loss; ELH is not exclusively an inner ear disease and can be caused by many conditions; any significant insult to the inner ear can affect vascular permeability or fluid regulation within the cochlea, leading to ELH
Clinical evaluation and diagnostic testing in patients presenting with sudden hearing loss: thorough history is essential to identify causative factors; sudden, forceful blowing of the nose can cause perilymph fistula; elicitation of dizziness with the tragal pumping test suggests fistula formation; audiography must be performed as soon as possible; if unavailable, a tuning fork can be used to differentiate between conductive and true sensorineural hearing loss (Rinne and Weber tests); if it is the latter, treatment may be started while awaiting audiography; videonystagmography is not needed for patients with sudden hearing loss; audiography, including air and bone conduction and speech, guides therapy; MRI — indicated for every patient with sudden hearing loss; any lesion > 2 mm in size can be seen on MRI of the internal auditory canal (IAC) with construction interference in steady state (CISS) sequence; contrast is not needed for every patient; computed tomography (CT) — not needed unless MRI is contraindicated, eg, in patients with implantable pacemakers; in such cases, obtain CT of the temporal bone with soft tissue windows, with and without contrast; if tumor is present, the IAC is not well visualized on soft tissue windows; in bone windows, abnormal IAC diameter may indicate a tumor mass, in which case the patient should undergo repeat CT after ≈ 1 yr; CT is most beneficial if tumor has protruded out of the IAC; laboratory studies — unnecessary unless sudden hearing loss is bilateral or other abnormalities (eg, thickened tympanic membrane) are present
Steroids for sudden hearing loss: traditionally, treatment included systemic steroid therapy, as hearing loss was considered a result of inflammation; steroids are effective for aborting migraines and may have beneficial effects on neurogenic aspects of migraine and the vascular component of hearing loss; intratympanic steroids may be substituted for oral steroids when treating, eg, patients with uncontrolled diabetes
American Academy of Otolaryngology-Head and Neck Surgery Clinical Practice Guidelines
Initial evaluation: per recommendations updated in 2019, the first recommendation is to exclude conductive hearing loss, preferably via audiography; if audiography is unavailable, tuning forks of different frequencies may be used to identify sensorineural hearing loss; if triaging of sudden hearing loss is being performed during a telephone call or other virtual consultation, asking the patient to hum can be useful; if sounds are louder in the affected ear, the likely cause is conductive loss related to presence of fluid or upper respiratory infection; otherwise, the patient requires immediate hearing testing
History and examination: thorough clinical history and physical examination are recommended for patients with sudden, bilateral hearing loss, recurrent episodes of temporary hearing loss, or focal neurologic signs; ask about history of acoustic trauma, barotrauma, head trauma, or fluctuating loss; assess for neurologic signs, such as headache, confusion, diplopia, dysarthria, weakness, or focal hypoesthesia, as well as for eye pain, redness, lacrimation, photophobia, oscillopsia, and/or nystagmus (especially if downbeat or gaze-evoked); some of these findings (eg, headache, hypoesthesia of the scalp, neck stiffness, eye pain, redness, lacrimation, photophobia) also may be present in patients with migraine; it is crucial to differentiate meningitis or intracranial mass from migraine
Other etiologic factors: those listed by the Academy include Ramsay-Hunt syndrome (presents with vesicles in the ear), meningitis (presents with fever), ototoxic medications (associated with vestibular loss and oscillopsia), trauma and barotrauma, lead poisoning (rarely causes neuropathy), genetic conditions, mitochondrial disorders, Cogan syndrome, neoplasms, and sarcoidosis
Diagnosis and initial treatment: avoid CT; obtain audiography as soon as possible, within 14 days of symptom onset; unavailability of audiography should not preclude discussion and initiation of treatment; the Academy strongly recommends against performing routine laboratory testing is unless there is high suspicion for an autoimmune or other disease, or if sudden hearing loss is bilateral; retrocochlear pathologies should be evaluated; educate the patient about the natural history and benefits of medical intervention; initial steroid therapy should be offered within 2 wk of onset of symptoms; even if the patient presents after 2 wk, a trial of steroid therapy is worthwhile; patients with concurrent active migraine symptoms (eg, neck stiffness, pressure in the ear, dizziness) are more likely to recover
Steroid therapy: the mainstay of medical treatment of sudden hearing loss; can be administered orally or via intratympanic injections; there is no advantage to intravenous administration
Intratympanic administration: outcomes are difficult to assess and compare because of the use of multiple drug doses, regimens, and techniques; results are technique-sensitive and dosage-dependent; the patient must be instructed to refrain from swallowing while the medication is placed in the inner ear and for 30 min after injection; speaker’s technique — the patient is placed in a reclined position at a 30- to 40-degree angle and tilted 15 degrees sideways to facilitate concentration of the steroid near the round window in the posteroinferior quadrant of the middle ear; the injection is placed in the anterosuperior quadrant to facilitate filling the middle ear; posterosuperior injection is an option if anterosuperior placement is not feasible; in the posterosuperior quadrant, care must be taken to avoid the chorda tympani nerve branch; if phenol is used, the amount should not exceed that necessary for passage of a 25-G needle; methylprednisolone produces a burning sensation that can be avoided by mixing a small amount of lidocaine to the solution (ie, 0.125 mg of lidocaine to 0.875 mg of methylprednisolone), as larger quantities of lidocaine may cause dizziness
Studies: Rauch et al found no significant difference in efficacy between oral and intratympanic steroids; a study by Battaglia found that patients who received a combination of oral and intratympanic steroid therapy had faster and better chances of hearing recovery than those on oral or intratympanic therapy alone; therefore, combination therapy should be started from the day of presentation; another study by Battaglia found that, in patients with severe hearing loss (ie, loss of > 70 dB), use of combination therapy within 7 days of onset was associated with recovery of serviceable hearing in 40%
Steroid doses: studies suggest that oral prednisone should be given at a dose of of 1 mg/kg per day in a single, undivided dose; the maximum dose is 60 to 80 mg/day for 10 to 14 days; the speaker uses a maximum dose for 7 days, followed by a taper over 6 to 8 days; to avoid issues associated with intratympanic methylprednisolone, the speaker favors dexamethasone 10 mg/mL for this route (the 4 mg/mL formulation of dexamethasone is ineffective); one study suggests a concentration of 24 mg/mL is more effective, but obtaining that concentration poses significant logistic and financial challenges
Hyperbaric oxygen (HBO) therapy: an optional adjunct to steroids within 2 wk of onset of symptoms or in patients who have shown insignificant improvement after 1 mo of therapy; not covered by most health insurance plans; a Cochrane review found no significant benefit of HBO therapy when the primary outcome is 50% improvement in hearing but significant benefit if the primary outcome is 25% improvement; the likelihood of recovery is lower if HBO is started 2 to 4 wk after the onset of symptoms; the Academy states that the efficacy of HBO therapy is best when administered within the first 2 wk of onset of sudden hearing loss
Salvage therapy: the Academy discussed the use of intratympanic steroids for salvage therapy in patients with incomplete recovery after 2 to 6 wk; the speaker encourages use of intratympanic steroids in combination with oral steroids as initial therapy
Additional recommendations: the Academy strongly recommends against routine use of vasoactive drugs; follow-up audiology should be obtained at the conclusion of therapy; auditory rehabilitation should be discussed with the patient
Speaker’s Experience
Migraine and sudden hearing loss: some patients with sudden hearing loss report migraine features, including ipsilateral neck stiffness (atypical migraine feature) or ipsilateral hypoesthesia or paresthesia of the scalp; such symptoms should alert the clinician to a migraine phenomenon; some patients with migraine do not have a documented diagnosis of the disorder; in this group of patients, the speaker adds 2 medications for migraine prophylaxis (eg, nortriptyline and topiramate) to combination steroid therapy; patients who received combination therapy plus migraine prophylaxis showed faster and better improvements in hearing
Chronic sudden hearing loss: a study by the speaker’s group included patients with onset of sudden hearing loss an average of 4 mo before presentation; many had aural fullness and concurrent headache; nortriptyline 25 mg (dosage increased every 2 wk, up to a maximum of 75 mg) and topiramate 25 mg (dosage increased by 25 mg/wk, up to a maximum dose of 150 mg) were prescribed; patients who failed to improve received 2 intratympanic steroid injections; those who had not received oral steroids received a single course; outcomes — 14% of patients returned to baseline by an average of 7 mo (median, 4 mo) after symptom onset; word discrimination improved by a mean of 35%; one-third of these patients improved from nonserviceable to serviceable hearing
Readings
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