Introduction: Isolated cranial nerve involvement is rare in patients with multiple sclerosis (10.4%) and extremely rare is an eighth nerve palsy, especially in the context of a clinically isolated syndrome (<1%).
Case report: A 34-year-old male presented with a history of left-sided tinnitus and sudden sensorineural hearing loss (SSNHL). Magnetic resonance imaging of the brain revealed >9, nonenhancing periventricular and corpus callosum lesions. Brainstem auditory evoked potentials were abnormal, ipsilateral to the affected ear, consistent with the presumed underlying demyelinating pathology. Visual evoked potentials showed bilateral prolonged P100 latencies. Oligoclonal bands were not detected in the cerebrospinal fluid, but IgG index was marginally elevated. After administration of corticosteroids, the patient recovered auditory function over a several month period.
Conclusions: This report describes a case of SSNHL in the context of magnetic resonance imaging of the brain and electrophysiological findings consistent with a demyelinating etiology. SSNHL is a rare and possibly underrecognized manifestation of clinically isolated syndrome.