頭位性めまいを主訴に来院した小脳動静脈奇形の1例

A Case of Arteriovenous Malformation Presented with Positional Vertigo

　はじめに

　頭位性めまいを訴えて来院する患者は多いが，その大多数は内耳障害による良性発作性頭位眩暈症（benign paroxysmal positional vertigo：BPPV）である。しかし，中枢前庭障害に起因する頭位性めまい，いわゆる悪性発作性頭位眩暈症（malignant paroxysmal positional vertigo：MPPV）の症例もこの中に混在し，類似の症状を主訴に来院することがあり，鑑別が重要である。今回われわれは，頭位性めまいを主訴に来院し，神経耳科学的検査が診断に有用であった小脳動静脈奇形（arteriovenous malformation：AVM）症例を経験したので報告する。

A 25-year-old man presented with positional vertigo. He has experienced vertigo lasting for about 15 seconds when he got up. On examination, vertical positional and positioning nystagmus wereobserved. He showed saccadic pursuit and mild disturbance of optokinetic nystagmus. Central lesions were suspected, and MRI revealed arterio-venous malformation from the vermis of the cere-bellum to the dorsal pons. Patients complaining of positional vertigo are often seen. While most of them are diagnosed as benign paroxysmal positional vertigo, some patients may have lesions in the central nervous system. This case suggested that we should be careful for diagnosis of positional vertigo.