Taste‐strip gustometry in cochlear implanted patients

OBJECTIVE: Investigation of the gustatory function in a large cohort of cochlear implanted patients using lateralized taste‐strip tests. PATIENTS AND METHODS: One hundred and seven unilaterally or bilaterally profoundly hearing impaired or deaf patients who received cochlear implants (n = 113) were included in this study. Data on gustometry, subjective gustatory dysfunction, and the detailed surgical procedure were acquired retrospectively. Gustatory function, assessed using lateralized taste‐strip tests, was performed the day before, 3 days after cochlear implantation, and on the day of the initial CI adjustment (39 days ±7.3 SD). RESULTS: Averaged taste‐strip scores of the cohort declined significantly from preoperatively 12.3 [11.8; 12.7] (mean [95% confidence intervals]) to 10.5 [9.7; 11.2] on the implanted side about 6 weeks after surgery. Patients with intraoperatively exposed and rerouted, or a severed, chorda tympani nerve (CTN) showed significantly reduced unilateral postoperative scores (10.1 [8.8; 11.4] and 9.3 [8.1; 10.5], respectively), when compared to not exposing or to leaving a bony layer over the CTN. Total taste‐strip test scores showed a significant decline 6 weeks postoperatively in CI‐patients expressing a subjective gustatory dysfunction (from 23.6 [21.4; 25.8] to 17.5 [14.2; 20.8]), as opposed to patients with a documented subjectively normal taste. CONCLUSION: We consider postoperative gustatory dysfunction as a relevant side effect post cochlear implantation, at least within the first month. Taste‐strip based gustometry is a suitable diagnostic tool to assess taste function in CI patients and is recommended to be performed routinely. LEVEL OF EVIDENCE: 3, retrospective, nonrandomized follow‐up study.