Unusual complication of tonsillectomy: taste disturbance and the lingual branch of the glossopharyngeal nerve

Taste disturbance is an unusual complication of tonsillectomy of which there are very few reports in the literature. The possible causes of this rare complication are: (1) direct or indirect damage to the glossopharyngeal nerve or its lingual branch (LBGN), (2) lack of dietary zinc, and (3) habitual drug intake.We report a 41-year-old man, who complained of taste disturbance following tonsillectomy that was performed for chronic tonsillitis and unilateral (left) tonsillar hypertrophy. During surgery, hypertrophic tonsils were found to be sited deeply into the tonsillar bed, especially at the lower pole of the left tonsil. Pathologic examination following tonsillectomy revealed a keratinous cyst and chronic infection at the left tonsil, and lymphoid hyperplasia and chronic infection at the right tonsil. Although his complaint had been getting better, qualitative examination of his taste function revealed bilateral impairment of the sense of sweet taste on the base of his tongue two months after the surgery, and a taste disturbance of sweet taste on the left side persisted the 10th month after the surgery. His serum zinc value was normal, and he did not take any drug that could affect his sense of taste. Depending on the literature data, possible indirect damage to the LBGN was suspected as the cause of the taste disturbance. This symptom may be reversible within two years after tonsillectomy, but it can also be irreversible. Therefore, tonsillectomy should be performed with minimal trauma to the tonsillar bed, especially when there is an additional pathology extending into the lower pole, and such a patient should be informed of the risk of post-operative taste disturbance after tonsillectomy as being one of the rare complications of this surgery.