The Impact of Different Manipulations of the Chorda Tympani Nerve on Taste in Endoscopic Ear Surgery

Abstract

The chorda tympani nerve (CTN) plays a significant role in taste transmission and salivary secretion. Due to its course in the tympanic cavity and its relation to the ossicular chain, there is a high risk of iatrogenic damage to the CTN during otologic surgeries. This study aimed to assess the impact of different handling methods of the CTN during endoscopic ear surgery on patients' taste perception. A cohort study conducted from 2022 to 2023 in a tertiary hospital involved participants undergoing various types of endoscopic ear surgeries. Based on intraoperative handling of the CTN, participants were divided into three groups: intact, traction (subdivided into mild, moderate and severe traction subgroups) and transection (subdivided into transection without tension, with tension and tearing subgroups). Taste tests were administered from 1 day before surgery to 6 months postoperatively. Endoscopic ear surgery for treating ear pathologies. Taste test scores, other relevant symptoms. Significant differences were observed in the incidence and recovery time of taste dysfunction across groups. The rate of taste abnormalities and recovery time increased with the degree of traction; the severe traction and transection subgroups showed the highest rates of abnormalities and cases of incomplete recovery. In terms of disease type, patients with chronic suppurative otitis media and cholesteatoma showed significant differences in preoperative taste status, abnormality rates and recovery times compared to patients with non-inflammatory ear diseases. General sensory abnormalities of the tongue were mainly found in moderate-to-severe traction subgroups and all transection groups, often accompanying taste reduction or loss. Some patients in the transection group experienced only numbness or both increased taste sensation and numbness. The study underscores the importance of delicate handling of the CTN in endoscopic ear surgery, especially in patients with inflammatory middle ear diseases. It suggests minimising severe traction injuries and considering early and accurate transection to reduce traction injuries when preservation is challenging; any manipulation of the CTN should be avoided in patients with non-inflammatory conditions. This research provides valuable theoretical support for clinical practice.