A 35-year-old woman had chief complaints of a burning sensation and numbness of the right side of the lip and tongue, as well as a dry sensation of the mouth with a taste disturbance of the right side of the tongue. It did not present sharp, shooting, and shock-like pain. These symptoms were predominant on the right side. The symptoms were continuous and did not show any daily fluctuations. Even though she presented numbness on the tongue, she could move it smoothly. Her speech was not affected by the burning sensation. The patient’s medical history included uterine fibroids, irritable bowel syndrome, and migraine. In her twenties, she visited a psychiatrist but the diagnosis was unclear. Six months before her first visit to our clinic, the symptoms started without any recognizable triggering factor. She also visited the oral surgery department in a general hospital, where she was prescribed xylocaine jelly and carbamazepine 200 mg /day. However, her symptoms were not relieved. Because the patient had irritable bowel syndrome, insomnia, and a busy and stressful life, she was referred to the psychosomatic dental clinic in Tokyo Medical and Dental University Dental Hospital. At her first visit, we conducted a structured medical interview and intraoral examination, but no abnormality was detected. Allodynia, ulcer, and swelling of the tongue were absent. Herpes infection was excluded by antibody testing. The visual analog scale score for pain intensity was 69, and the Zung’s self-rating depression scale score was 48, which was almost the upper normal limit. For the neurological testing, Semmes-Weinstein monofilament testing on the region of second and third branch of the trigeminal nerve also presented no sensory abnormality. Unlike the typical feature of BMS, food intake did not ease the symptoms. Therefore, magnetic resonance imaging (MRI) examination was scheduled to rule out intracranial causes. MRI images revealed an approximately 30 × 30 mm well-defined mass localized in the right cerebropontine angle compressing the trigeminal nerve, which was diagnosed as schwannoma of the right auditory nerve (Fig.
1). The additional symptoms besides pain described may have been due to the tumor compression affecting cranial nerve VII. At this point, we referred the patient to a neurosurgeon who confirmed that the patient had been suffering from hearing loss for three months. The tumor was successfully removed by surgery. Hematoxylin and eosin staining showed spindle cells and a fasciculated, palisading pattern (Fig.
2). The cells showed positivity to S-100 protein. The diagnosis of schwannoma of the right auditory nerve was confirmed. Though her facial paralysis showed slight improvement, the patient’s oral burning sensation and numbness persisted for 1.5 years after the surgery. While the patient could not perceive sour and salty tastes, she reported vague perception of sweet and bitter ones.