Stapedius reflex in patients with an inner ear prosthesis.

The stapedius reflex elicited by electrical stimulation was investigated in 21 deaf individuals supplied with an inner ear prosthesis. All patients were implanted with the Vienna cochlear implant using intra or extracochlear electrodes. Analog stimulation with sinus bursts of various durations (25, 50, 100, 300, 500 ms) and frequencies (125, 500, 1000, 2000 Hz) was used. The time course of the contralateral acoustic reflex was monitored using a fast-response impedance meter. The stapedius reflex was observed in about half of the cases. Reflex threshold was observed at a stimulation level close to uncomfortable loudness. The time course in case of electrical stimulation differs in some aspects (rise time, onset) from acoustic stimulation in hearing individuals. Temporal integration of the stapedius reflex was observed also in case of electrostimulation through the cochlear implant.