Evidence of chorda tympani dysfunction in patients with burning mouth syndrome

More than two-thirds of patients with burning mouth syndrome (BMS) have altered taste sensation. The authors conducted a study to assess chorda tympani and trigeminal nerve function in these patients.

The study was composed of 48 patients; 22 were diagnosed as having BMS, 14 had burning symptoms related to other diseases and were diagnosed as having secondary burning mouth syndrome (SBMS), and 12 were healthy volunteers. The authors evaluated the electrical detection thresholds of the infraorbital and mental nerves and the electrical taste and electrical detection/tingling thresholds in the anterior two-thirds of the tongue for all patients. Electrical taste threshold is thought to be dictated by chorda tympani nerve function while electrical detection/tingling thresholds are regulated by trigeminal nerve function.

The mean electrical taste/tingling detection thresholds ratio and the taste detection thresholds were significantly higher in patients with BMS than in patients with SBMS and in control subjects, indicating chorda tympani nerve dysfunction. Eighteen (82 percent) of the 22 patients with BMS demonstrated chorda tympani dysfunction (13 unilateral and five bilateral).

Chorda tympani hypofunction may play an important role in BMS pathology. Unilateral hypofunction may be sufficient to produce generalized burning sensation exceeding the affected nerve area.

Elevated taste detection threshold levels determined via electrogustatory testing and an elevated taste/tingling detection thresholds ratio may assist clinicians in the diagnosis of BMS. More studies are needed to validate these findings.