How should sensorineural hearing loss be evaluated and managed?

Evaluation and Management of Sensorineural Hearing Loss

Sensorineural hearing loss requires immediate differentiation from conductive hearing loss through physical examination and tuning fork testing, followed by urgent audiometry within 14 days—particularly for sudden-onset cases—and MRI evaluation for asymmetric presentations to exclude retrocochlear pathology. 1, 2

Initial Clinical Evaluation

Distinguish SNHL from Conductive Hearing Loss

• Perform otoscopic examination to identify conductive causes: cerumen impaction, tympanic membrane perforation, middle ear effusion, cholesteatoma, foreign bodies, or canal stenosis must be excluded before diagnosing SNHL. 1, 2
• Use Weber and Rinne tuning fork tests (256 or 512 Hz): In Weber testing, sound lateralizing to the affected ear suggests conductive loss, while lateralization away from the affected ear indicates SNHL in the opposite ear. In Rinne testing, air conduction louder than bone conduction is normal; bone conduction louder than air conduction indicates conductive hearing loss. 1, 2
• Remove impacted cerumen before establishing any diagnosis, as this is a treatable cause of conductive hearing loss that can mask or mimic SNHL. 1

Identify Red Flags Requiring Urgent Action

• Assess for sudden onset (within 72 hours): This constitutes an otologic emergency requiring immediate evaluation and treatment initiation. 1, 2
• Evaluate for bilateral hearing loss, recurrent episodes, or focal neurologic findings (cranial nerve deficits, ataxia, visual changes), as these suggest serious underlying pathology requiring immediate specialist referral. 1, 2
• Document associated symptoms: tinnitus, vertigo, ear fullness, oscillopsia, or pulsatile tinnitus warrant urgent otolaryngology evaluation. 1, 2

Audiometric Confirmation

Timing and Indications

• Obtain comprehensive audiometry within 14 days of symptom onset for sudden hearing loss to confirm diagnosis, quantify severity, and establish baseline for monitoring. 1, 2
• Audiometry is mandatory for: unilateral hearing loss, asymmetric hearing loss, sudden-onset hearing loss, persistent symptoms ≥6 months, or any hearing difficulty requiring evaluation. 1, 2

Diagnostic Criteria

• Sudden sensorineural hearing loss is defined as: ≥30 dB decrease at 3 consecutive frequencies occurring within 72 hours. 1
• Asymmetric sensorineural hearing loss is defined as: ≥15 dB difference at 2 or more frequencies between ears, ≥15% difference in speech recognition scores, ≥20 dB difference at 2 contiguous frequencies, or ≥15 dB difference at any 2 frequencies between 2000-8000 Hz. 1, 3
• Poor word recognition is defined as: unaided monosyllabic word score ≤60%, which warrants specialist referral. 1

Imaging Studies

MRI for Retrocochlear Pathology

• Order MRI with dedicated internal auditory canal protocol for: asymmetric sensorineural hearing loss, sudden sensorineural hearing loss, unilateral tinnitus, poor word recognition, or focal neurologic findings. 1, 2, 3
• Use high-resolution 3-D T2-weighted sequences with thin sections across the internal auditory canals and inner ear to detect vestibular schwannomas (5.4% prevalence in sudden SNHL), meningiomas, labyrinthitis, or neuritis. 2, 3
• Gadolinium contrast facilitates visualization of inflammatory changes and enhances detection of tumors, though non-contrast protocols may be adequate for screening. 2, 3

CT Temporal Bone

• Order CT temporal bone when: history suggests temporal bone fracture or head trauma, clinical suspicion for otosclerosis, evaluating for superior semicircular canal dehiscence, or assessing ossicular chain abnormalities. 2, 3

What NOT to Order

• Do not order routine head CT in the initial evaluation of sudden sensorineural hearing loss, as it lacks sensitivity for inner ear and retrocochlear pathology. 1

Laboratory Testing

General Approach

• Do not obtain routine laboratory tests in idiopathic sensorineural hearing loss, as they lack proven benefit and are not cost-effective. 1, 2

Targeted Testing Only When Clinically Indicated

• Order serologic testing only when history or examination suggests specific conditions: autoimmune inner ear disease (bilateral fluctuating hearing loss with systemic symptoms), Lyme disease (endemic areas with appropriate exposure history), syphilis (risk factors or systemic signs), HIV (risk factors), or inflammatory markers for suspected autoimmune conditions. 1, 2, 3

Treatment Considerations for Sudden Sensorineural Hearing Loss

Initial Therapy (Within 2 Weeks of Onset)

• Offer oral corticosteroids as initial therapy without waiting for imaging results, as early treatment improves outcomes. 1, 3
• Hyperbaric oxygen therapy combined with steroids may be offered within 2 weeks of onset as an option, though access is limited. 1

Salvage Therapy (2-6 Weeks After Onset)

• Offer intratympanic steroid therapy for incomplete recovery or treatment failures presenting 2-6 weeks after symptom onset. 1, 3
• Hyperbaric oxygen combined with steroids may be offered as salvage therapy within 1 month of onset. 1

What NOT to Prescribe

• Do not routinely prescribe antivirals, thrombolytics, vasodilators, or vasoactive substances, as these lack evidence of benefit in idiopathic sudden sensorineural hearing loss. 1

Specialist Referral

Immediate Otolaryngology Referral Required For:

• Sudden sensorineural hearing loss (within 72 hours) 1, 2
• Bilateral sudden hearing loss 1, 2
• Asymmetric sensorineural hearing loss (after audiometry confirms diagnosis) 1, 3
• Focal neurologic findings 1, 2
• Pulsatile tinnitus 2
• Severe vestibular loss with oscillopsia 2
• Poor word recognition (≤60%) 1
• Conductive or mixed hearing loss requiring surgical evaluation 1

Audiologic Rehabilitation

Timing and Indications

• Counsel patients with residual hearing loss and/or tinnitus about audiologic rehabilitation benefits as soon as hearing loss is identified. 1, 3
• Refer to audiology for hearing aid evaluation and fitting to address impacts on communication, sound localization, safety, and quality of life. 3
• Obtain follow-up audiometry at conclusion of treatment and within 6 months to assess response and adjust management. 1, 3

Common Pitfalls to Avoid

• Do not delay audiometry: Confirmation of hearing loss type and severity guides all subsequent management decisions, and delays worsen outcomes for sudden sensorineural hearing loss. 1, 2
• Do not assume hearing loss is conductive without examination: Impacted cerumen must be removed and otoscopy performed before diagnosing SNHL. 1
• Do not skip MRI for asymmetric or sudden SNHL: Retrocochlear pathology must be excluded, as vestibular schwannomas occur in 5.4% of sudden SNHL cases. 2, 3
• Do not order MRI for routine age-related hearing loss: Reserve imaging for asymmetric, sudden, or unilateral presentations. 2
• Do not order routine labs or head CT: These lack proven benefit and delay appropriate management. 1, 2