The Effect of Ototoxic Sodium Salicylate on DPOAE and Cochlear Blood Flow in Guinea Pig

Hwang, Chan Ho; Chang, Sun O

Abstract

BACKGROUND AND OBJECTIVES: Salicylate is one of the most commonly prescribed drugs although it has been recognized that salicylate induces hearing loss and tinnitus reversibly. There are many presumed mechanisms of salicylate ototoxicity including an impairment of the cochlear blood circulation. But the exact mechanism of salicylate ototoxicity is not known clearly. The purpose of this present study was to determine if the decreased blood flow after salicylate injection could be the possible cause of hearing loss. MATERIAL AND METHODS: We used the ventral approach to expose cochlea in 5 guinea pigs showing normal Preyer reflex. We simultaneously measured cochlear blood flow (CBF) by laser doppler and distortion product otoacoustic emission (DPOAE) after a high dose of salicylate injection (300 mg/kg).
RESULTS
After salicylate injection, the cochlear blood flow were decreased by 29.1 % in a 3 hour period and the thresholds of DPOAE were elevated by 5 to 25 dB for 3 kHz, 4 kHz, 6 kHz, 8 kHz.
CONCLUSION
Sodium salicylate caused a decrease in cochlear blood flow and an increase in the hearing threshold simultaneously after an intraperitoneal injection of sodium salicylate. These findings suggest that the ototoxic mechanism of sodium salicylate could be explained by a certain damage of out hair cell due to decrease in cochlear blood flow.