Usefulness of the Taste Test Using Filter-paper Disc in Treatment of Dysgeusia due to Chorda Tympani Nerve Damage

—A Case of Taste Disorder Following Surgery for Middle Ear Cholesteatoma—

Abstract

Taste disorder in the anterior two-thirds of the tongue is caused by injury to the chorda tympani nerve （CTN）. We report a case of taste disorder following surgery for otitis media caused by middle ear cholesteatoma （MEC）. A female in her 60s presented to our department with persistent dysgeusia since dental treatment. A taste test, electrogustometry （EGM） and the filter paper disc method （FPD） revealed the taste disorder only in the unilateral CTN area. Although she insisted that the dysgeusia was associated with dental treatment, a detailed dental examination and history of dental diseases revealed no abnormalities. A detailed medical interview revealed that she had undergone ear surgery around the same time as dental treatment. Surgical and imaging findings provided by an otolaryngologist indicated that she had received surgery for otitis media following MEC that had caused CTN dysfunction. During prolonged follow-up, dysgeusia showed a better correlation with FPD than EMG. FPD may be useful for assessing dysgeusia caused by injury to CTN. Dentists should pay close attention to dental treatment and cooperate with an otolaryngologist when middle ear surgery is undergone at the same time.