Characteristics of preoperative electrically evoked middle latency responses and postoperative cochlear implant effects in patients with tinnitus.

OBJECTIVE

To analyse the characteristics of electrically evoked middle latency responses (EMLR) in patients with profound sensorineural hearing loss (SNHL) and tinnitus.

METHODS

Thirty adults with profound SNHL and tinnitus who underwent cochlear implantation were selected as the tinnitus group, and 15 patients with profound SNHL but without tinnitus served as the control group. Preoperative data were retrospectively analysed. Electrically evoked middle latency responses were recorded intraoperatively, and the electrophysiological characteristics were compared between groups. Changes in tinnitus were assessed using the Tinnitus Handicap Inventory (THI), and correlations between EMLR parameters and THI scores were analysed.

RESULTS

No postoperative complications occurred in any of the patients. Electroauditory responses were successfully elicited in all 45 patients. Intraoperative EMLR showed increased Na-Pa amplitude and delayed Pa latency, with significant differences observed between the tinnitus and control groups (P < 0.05). One year after cochlear implantation, the average comfort level (C value) and the EMLR threshold showed a significant linear correlation (r = 0.915, P < 0.01). Postoperative THI scores showed a significant decrease (P < 0.05) compared with preoperative scores. A significant correlation was found between the intraoperative EMLR Na-Pa wave amplitude and THI change at 1 year (r = 0.815, P < 0.05), with an area under the ROC curve of 0.673 (P = 0.002).

CONCLUSION

The intraoperative EMLR waveform of patients with profound SNHL and tinnitus is significantly different from that of patients without tinnitus. Cochlear stimulation effectively inhibits tinnitus, and EMLR provides an objective tool for evaluating tinnitus and optimising its management. However, further studies with larger sample sizes are needed to validate these preliminary findings.