Absence of contralateral suppression of transiently evoked otoacoustic emissions in fibromyalgia syndrome.

OBJECTIVE To assess contralateral suppression of transiently evoked otoacoustic emissions in patients with fibromyalgia syndrome and normal hearing. METHODS Twenty-four female patients with fibromyalgia syndrome and 24 healthy female controls with normal hearing were assessed using pure tone audiometry and transiently evoked otoacoustic emissions. RESULTS All patients with fibromyalgia syndrome and all controls had normal hearing on pure tone audiometry. In the patients with fibromyalgia syndrome, the mean transiently evoked otoacoustic emission amplitude was 15.5 +/- 4.8 dB. The mean transiently evoked otoacoustic emission amplitudes after contralateral suppression was 15.5 +/- 4.9 dB. There was no statistically significant difference between the transiently evoked otoacoustic emission amplitudes measured before and after contralateral suppression (p > 0.05). In the controls, the mean transiently evoked otoacoustic emission amplitude was 12 +/- 5 dB. The mean transiently evoked otoacoustic emission amplitudes after contralateral suppression was 11 +/- 4.7 dB. There was a statistically significant decrease in transiently evoked otoacoustic emission amplitudes after contralateral suppression (p < 0.01). CONCLUSION The mechanisms related to contralateral suppression of transiently evoked otoacoustic emissions seem dysfunctional in fibromyalgia syndrome. This dysfunction may be at the brain stem level, where the medial superior olivary complex is located, or at the synapses of medial superior olivary complex fibres with the outer hair cells in the cochlea. Demonstration of lack of contralateral suppression of transiently evoked otoacoustic emissions can be used as a diagnostic tool in patients with fibromyalgia syndrome.