Effect of intratympanic dexamethasone on noise-induced temporary threshold shift

Objective. To evaluate the effects of intratympanic treatment of dexamethasone (IT-DEX) and combination of DEX and hyaluronic acid (DEX/HA) for noise-induced temporary threshold shift (NITTS). Materials and Methods: NITTS was experimentally performed in 60 rats. Electrophysiologic hearing thresholds of the rats were measured before and right after noise exposure. Then, the rats were placed into two groups, the first 30 rats in an IT-DEX group and the second in an IT-DEX/HA group. Treatments were performed in the two subgroups (30 ears in one subgroup) of each group. In the IT-DEX group, one ear of each rat was treated with 0.02 mL IT-DEY, and the other ear was treated with IT 0.02 mL physiologic solution of serum saline. In the IT-DEX/HA group, one ear of each rat was treated with combination of 0.01 mL IT-DEX and 0.01 mL HA, and the other ear was treated with IT 0.02 mL of physiologic solution of serum saline. One week after the treatments, electrophysiologic hearing thresholds of all rats were measured again. Results. No statistically significant difference was observed in recovery values of electrophysiologic hearing thresholds between IT-DEX and serum saline (P = .641) in the IT-DEX group. Also, we found no statistically significant difference in the recovery values of electrophysiologic hearing thresholds between IT-DEX/HA and serum saline (P = .344) in the IT-DEX/HA group. Conclusion: There is no effect of either IT-DEX and DEX/HA for NITTS.