Association between chorda tympani manipulation time and early taste disturbance after primary stapes surgery

The aim of this study was to investigate the association between intraoperative chorda tympani nerve (CTN) manipulation time and early postoperative taste disturbance after primary stapes surgery.

This retrospective study included 56 patients who underwent primary stapes surgery. CTN manipulation time was measured objectively using archived surgical video recordings. Early postoperative subjective taste symptoms were assessed at postoperative week 1 using a patient-reported ordinal scale. Patients were grouped according to manipulation duration, and taste outcomes were compared. Receiver operating characteristic (ROC) analysis was performed to determine the discriminative ability of manipulation time and identify an optimal cutoff value. In addition, logistic regression analysis was performed to evaluate the association between CTN manipulation time as a continuous variable and the risk of postoperative taste disturbance. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

Postoperative taste disturbance occurred in a total of 13 patients (23.2%), including 3 patients (10.7%) in the short manipulation group and 10 patients (35.7%) in the long manipulation group (Fisher's exact test p = 0.041; OR = 4.63). Postoperative taste scores were significantly lower in the long manipulation group, with median scores of 3 (IQR: 2-3) versus 3 (IQR: 3-3) in the short manipulation group (p = 0.021). ROC analysis demonstrated high discriminative performance (AUC = 0.93; 95% CI: 0.80-1.00); however, given the limited number of outcome events, these findings should be interpreted as exploratory and hypothesis-generating. When CTN manipulation time was analyzed as a continuous variable, univariable logistic regression analysis demonstrated that longer manipulation time was significantly associated with an increased risk of postoperative taste disturbance (OR = 1.06 per second increase, 95% CI: 1.02-1.11, p = 0.008).

Prolonged CTN manipulation time may be associated with an increased risk of subjective early postoperative taste disturbance after primary stapes surgery and may reflect underlying surgical complexity and intraoperative conditions rather than a direct causal mechanism. However, given the potential influence of perioperative confounders, these findings should not be interpreted as indicating a direct causal relationship.