Change in chorda tympani nerve function after two-stage tympanoplasty for cholesteatoma.

Objectives: Chorda tympani nerve (CTN) function may be damaged more by two-stage than by one-stage surgery for middle ear cholesteatoma. However, few studies have reported the relationship between two-stage cholesteatoma surgery and CTN function. This study aimed to investigate CTN function after two-stage surgery for cholesteatoma.

Methods: In this prospective study, 35 patients underwent two-stage canal wall up tympanoplasty (CWUT). Perioperative CTN function was assessed using questionnaires and electrogustometry (EGM). Participants were categorized into minor, major, and section groups, based on the degree of CTN manipulation during surgery.

Results: In the first-stage surgery, posterior tympanotomy with an intact canal wall reduced the degree of CTN manipulation. The incidence of taste disorder after the first-stage surgery was 71.4%. Postoperative taste disorder and the EGM threshold improved early in the minor manipulation group. In the second-stage surgery, no new CTN damage occurred, even if this surgery involved removal of residual cholesteatoma. The incidence of taste disorder after second-stage surgery was less than that after first-stage surgery, independent of CTN preservation. However, the recovery rate of the EGM threshold after second-stage surgery was significantly lower in the section group than in those with CTN preservation.

Conclusion: CTN function, including symptoms and EGM threshold, can be preserved during two-stage cholesteatoma surgery if care is taken to preserve the CTN in both the first- and second-stage surgeries. A two-stage CWUT, ensuring an intact bony annulus, may be effective to facilitate CTN preservation.

Level Of Evidence: 2b.