Abstract
We report a case in which a neuro-otological examination led to the diagnosis of superior canal dehiscence syndrome (SCDS). Although SCDS can be suspected on the basis of a superior canal deficit finding on CT, bony thinning of the superior canal can occur with aging in normal adults. Therefore, even if a bone defect is found in the upper semicircular canal, it should not be diagnosed on the basis of CT findings alone because a thin bone wall may cover it. Thus, it is significant to confirm the presence or absence of fistula symptoms by neuro-otological examination. The patient, a woman in her 40s, had been aware of the symptoms of ear fullness and auditory hypersensitivity for two years. She was diagnosed as having a patulous Eustachian tube in another clinic and referred to our department for further examination and treatment. Audiometry revealed mild conductive hearing loss in the low-frequency range. The Eustachian tube function test showed no evidence of a patulous Eustachian tube. The nystagmus test using Valsalva stimulation revealed vertical and clockwise nystagmus in the lower eyelid direction. The vestibular-evoked myogenic potential (VEMP) showed an increased amplitude and a decreased threshold on the affected side. On the basis of subjective symptoms and the examination findings mentioned above, we diagnosed her as having left SCDS. In cases wherein the patient was treated for Eustachian tube dysfunction but the symptoms did not improve, it is helpful to perform neuro-otological tests to check for different diseases. Those tests are simple, noninvasive, and sometimes valuable for reaching an accurate diagnosis.
