What is the significance of sensorineural hearing loss in a young adult with demyelination on MRI?

Sensorineural Hearing Loss with Demyelination on MRI in a Young Adult

The combination of sensorineural hearing loss and demyelination on MRI in a 25-year-old female strongly suggests multiple sclerosis (MS) as the underlying diagnosis, and this patient requires immediate neurological evaluation and consideration for corticosteroid therapy. 1

Clinical Significance and Diagnostic Implications

Demyelinating Disease as a Cause of SSNHL

• Demyelinating processes, particularly MS, are recognized causes of sudden sensorineural hearing loss (SSNHL) in young adults. 1, 2
• In MRI studies of patients with SSNHL, demyelinating processes account for approximately 2-7% of cases where MRI reveals a possible etiology for hearing loss. 1, 2
• MS can cause sensorineural hearing loss in 4-10% of patients, occurring during either relapses or remissions of the disease. 3, 4

Mechanism of Hearing Loss in Demyelinating Disease

• Acute inflammatory demyelination can affect the cochlear nerve or more central auditory pathways (brainstem and thalami), causing retrocochlear hearing loss. 5, 4
• The immune-mediated mechanisms of MS can involve both central auditory pathways and potentially peripheral structures of the inner ear. 4
• The most common presentation is unilateral, moderate-to-profound, sudden sensorineural hearing loss across all frequencies (250 Hz-8000 Hz). 4

Recommended Diagnostic Workup

MRI Protocol Requirements

• MRI with dedicated internal auditory canal (IAC) protocol is essential and should include evaluation of the brainstem and thalami, not just the IAC. 1
• High-resolution 3D T2-weighted sequences provide submillimeter assessment of the auditory pathways and can detect demyelinating lesions. 1
• Gadolinium contrast administration can facilitate visualization of inflammatory changes including neuritis and active demyelinating lesions. 1
• The MRI protocol should assess the entire brain parenchyma along the auditory pathways when demyelination is suspected, not just the IAC. 1

Audiological Testing

• Auditory brainstem response (ABR) testing is the most appropriate test for diagnosing sensorineural hearing loss in MS patients. 3, 4
• ABR can detect demyelinating lesions even when hearing recovers, as ABR abnormalities may persist despite clinical improvement. 4, 5
• ABR results may show abnormalities of wave I in cases with irreversible hearing loss, suggesting peripheral involvement. 4
• Pure tone audiometry (PTA) and auditory steady-state response (ASSR) should also be performed, as these tests may show different time courses of improvement compared to ABR. 5

Treatment Considerations

Corticosteroid Therapy

• Corticosteroids should be offered as initial therapy within 2 weeks of symptom onset for SSNHL. 1
• In MS patients with SSNHL, steroid therapy can lead to resolution of both clinical and audiological abnormalities. 5
• Intratympanic steroids may be offered as salvage therapy for incomplete recovery after initial systemic therapy. 1

Prognosis and Follow-up

• Approximately one-third to two-thirds of patients with SSNHL may recover some hearing within 2 weeks, but recovery patterns differ in MS patients. 1
• In MS-related SSNHL, audiological test results may show discordant recovery patterns, with PTA and ASSR normalizing before ABR. 5
• Follow-up audiometry should be obtained within 6 months of initial diagnosis. 1

Critical Clinical Pitfalls

Don't Miss the MS Diagnosis

• The presence of demyelination on MRI in a young adult with SSNHL mandates neurological consultation, as this may represent the presenting symptom of MS. 3, 4
• Audiovestibular symptoms can be early or presenting manifestations of MS, and early diagnosis allows for timely disease-modifying therapy. 4
• Additional symptoms to inquire about include tinnitus, balance abnormalities, aural pain, and aural fullness, which may accompany SSNHL or occur independently in MS. 4

Imaging Interpretation

• MRI has the highest diagnostic yield (7-13.75% pathogenic abnormalities) of any test in SSNHL, making it essential rather than optional. 1
• The radiologist should specifically evaluate for demyelinating lesions in the brainstem, thalami, and along the auditory pathways, not just screen for vestibular schwannoma. 1
• Evoked potentials (ABR, VEMPs, MLR) are sensitive for detecting demyelinating lesions and should be used complementary to MRI. 4

Treatment Timing

• Corticosteroid therapy is most effective when initiated within 2 weeks of symptom onset. 1
• In MS patients, prompt steroid treatment can prevent permanent hearing loss and may modify the disease course. 3, 5