めまい発作時の眼振所見を確認し得た神経血管圧迫症候群例

Neurovascular compression syndrome (NVCS) is a neurological disorder in which the intracranial blood vessels compress the cranial nerves. We report a case of NVCS of the VIII cranial nerve in which nystagmus was confirmed during vertigo attacks by ENG. The patient was a 32-year-old male who came to our department with the chief complaint of rotatory vertigo. He had no significant past medical history. He had 5–6 attacks of vertigo each year, lasting for about a minute each, without cochlear symptoms. He had been examined by a local neurosurgeon and otorhinolaryngologist, neither of whom found any abnormalities. When a detailed balance function test was performed, he had an accidental attack of vertigo just before the caloric test, and we could record an ENG during the attack. At first, leftward nystagmus appeared, and after it stopped, rightward nystagmus appeared after a change of direction. The nystagmus was approximately 120/30 sec. The maximum slow phase velocity was 100 deg/sec. The attack disappeared in about 2 minutes. Cranial MRI and MRA revealed a meandering left vertebral artery in contact with the base of the left VII and VIII cranial nerves. Based on the clinical findings, the patient was diagnosed as having NVCS of the VIII cranial nerve. The patient’s symptoms were relieved by carbamazepine. This is the first case reported in the world, with no report in the literature of ENG findings recorded during a vertigo attack of NVCS in the VIII cranial nerve. The ENG findings in this case complement previous reports and may help to elucidate the pathogenesis of NVCS of the VIII cranial nerve.