[Sudden hearing loss in a patient with a 3-mm acoustic tumor].

Sudden sensorineural hearing loss (SNHL) accounts for 1% of all SNHL cases. It has been reported that acoustic neuroma may be present up to 47.5% of patients with sudden SNHL. A 55-year-old man presented with sudden hearing loss in his left ear of 45-day history. Audiologic and transient evoked otoacoustic emission tests showed near-total hearing loss and absence of emissions in the left ear, respectively. Electronystagmography showed left canal paralysis and lack of response to the Kobrak test. The interpeak interval I-V latency and interaural amplitude differences in wave V latency were prolonged in auditory brainstem response. Computed tomography showed an increase in the diameter of the left internal acoustic canal, and magnetic resonance imaging (MRI) revealed an intracanalicular mass, 3 mm in size, originating from the left cochlear nerve. Another mass (18x17 mm) was detected that filled the right pontocerebellar cistern, suggesting a meningioma, but this was not thought to exert an obvious shift effect contributing to the development of left-sided hearing loss. Despite treatment with a tapered course of fluocortolone for 18 days the patient's hearing level did not change. He was included in a follow-up with MRI at six-month intervals.