Atypical hearing loss in acoustic neuroma patients

Audiologic data from 126 patients treated at the University of California, San Francisco for newly diagnosed acoustic neuromas (ANs) from 1986 to 1990 were reviewed. Subjectively normal hearing was present in 15% of patients and was most frequent in patients with small (< 1 cm) tumors. Only 4% had objectively normal hearing on the basis of speech reception threshold (SRT), speech discrimination score (SDS), and high-frequency pure-tone loss. This was most frequent in patients with < 1 cm tumors. Abnormal but symmetrical hearing is usually not considered to be indicative of a unilateral AN. In the present series, 7% of patients with ANs possessed symmetrical hearing. High-frequency asymmetry was a more sensitive indicator of the presence of an AN than differences in either SRT or SDS. The clinician must be aware of the relatively high incidence of atypical audiologic findings in acoustic tumor patients.