What is the initial management for a patient with asymmetric sensorineural hearing loss?

Management of Asymmetric Sensorineural Hearing Loss

The initial management for a patient with asymmetric sensorineural hearing loss should include MRI of the internal auditory canals to exclude retrocochlear pathology such as vestibular schwannoma or meningioma. 1

Diagnostic Approach

Initial Assessment

• Define asymmetric hearing loss (multiple criteria exist):
  • ≥15 dB HL at 2 or more frequencies, or ≥15% difference in speech recognition score 1
  • ≥15 dB HL at 3000 Hz 1
  • ≥20 dB HL at 2 contiguous frequencies, or ≥15 dB HL at any 2 frequencies between 2000-8000 Hz 1
  • ≥10 dB HL at 2000 Hz for those with history of loud noise exposure (military) 1

Imaging

• MRI with dedicated internal auditory canal (IAC) protocol is the imaging modality of choice 1

  • Use high-resolution 3-D T2-weighted images for submillimeter assessment of fluid-filled inner ear structures 1
  • Contrast administration may help visualize inflammatory changes or neoplasms 1
  • MRI can demonstrate signal alterations from inflammation/hemorrhage, identify neoplasms, assess vestibular aqueducts, and visualize auditory pathway abnormalities 1

• CT temporal bone should NOT be the primary imaging modality 1

  • Less sensitive than MRI for detecting retrocochlear pathology 1
  • Consider CT temporal bone only if:
    • History of head trauma suggests fracture 1
    • Evaluating for otosclerosis or other bony abnormalities 1

Special Considerations

Rule Out Sudden Sensorineural Hearing Loss (SSNHL)

• If hearing loss occurred rapidly within 72 hours, treat as SSNHL emergency 1, 2
• For SSNHL, initiate steroids within 14 days of onset:
  • Oral prednisone 1 mg/kg/day (max 60 mg) for 10-14 days with taper 2
  • Consider intratympanic steroid injections for severe loss or contraindications to systemic steroids 2

Evaluate for Other Causes

• Consider additional workup if history suggests:
  • Fluctuating hearing: Ménière's disease, autoimmune inner ear disease 1
  • Focal neurologic findings: stroke, multiple sclerosis 1
  • Bilateral hearing loss: Consider causes in Table 7 of guideline 1
  • Serological tests only if specific condition suspected by history 1

Follow-up Management

• Schedule audiometric follow-up within 6 months to monitor for progression 2
• For persistent asymmetric hearing loss:
  • Provide audiologic rehabilitation options 2
  • Consider hearing aids, contralateral routing of signal (CROS) devices for unilateral loss 2

Pitfalls to Avoid

• Delaying MRI evaluation can miss potentially serious retrocochlear pathology
• Using CT as primary imaging modality will miss many soft tissue abnormalities
• Assuming noise exposure as the cause without proper evaluation
• Failing to recognize SSNHL as an emergency requiring immediate intervention
• Ordering unnecessary serological tests without specific clinical suspicion

Algorithm for Management

1. Confirm asymmetric sensorineural hearing loss with audiometry
2. Determine acuity of onset (within 72 hours = SSNHL emergency)
3. Order MRI with IAC protocol as primary imaging study
4. Initiate appropriate treatment based on findings:
   • If SSNHL: immediate steroids
   • If vestibular schwannoma: refer to neurotology
   • If other pathology: directed treatment
5. Schedule follow-up audiometry to monitor progression
6. Provide hearing rehabilitation for persistent loss

Remember that despite extensive workup, the etiology of asymmetric sensorineural hearing loss often remains unclear in many cases 1.