Trough-Shaped Audiograms Are Common in Patients with Acoustic Neuroma and Sudden Sensorineural Hearing Loss.

Acoustic neuroma sometimes presents with sudden-onset sensorineural hearing loss as a primary symptom. We investigated 848 untreated cases that included 20 cases with acoustic neuroma with sudden-onset sensorineural hearing loss and 828 cases without acoustic neuroma. Fourteen of the 20 acoustic neuroma and 90 of the 828 cases of sudden-onset sensorineural hearing loss showed a trough-shaped audiogram with the greatest amount of hearing loss in the mid-frequency range. The incidence of a trough-shaped audiogram was significantly higher in patients with acoustic neuroma than in those without (p < 0.01). This study suggests that a trough audiogram is a significant finding in patients with sudden-onset sensorineural hearing loss and indicates the presence of acoustic neuroma.