著しい頭位性めまいをきたした動静脈奇形について

POSITIONING NYSTAGMUS IN A CASE OF POSTERIOR FOSSA ARTERIO-VENOUS MALFORMATION

　I．はじめに

　頭位ならびに頭位変換眼振検査は，めまい・平衡障害症例の診断上きわめて有用で，かつ，Frenzel眼鏡下に，手軽に行なえる検査法である。

　懸垂頭位〜坐位で眼振方向が逆，かつ純回旋性眼振がみられる良性発作性頭位眩量症の診断には，この頭位・頭位変換眼振検査が有用である。方向交代性上向性頭位眼振，垂直性頭位変換眼振は，小脳・脳幹の障害を物語り，小脳・脳幹のびまん性の障害や中心部の障害時にみられる。

　A 55-year-old female had a sudden attack of vertigo without tinnitus or loss of consciousness. The patient had gaze nystagmus, apogeotropic direction changing positional nystagmus, and downward vertical positioning nystagmus. She showed no cranial nerve and cerebellar involvement.

　The right carotid and vertebral angiographies showed an arteriovenous malformation in the posterior inferior part of the right cerebellar vermis, in which feeding arteries were a part of the posterior cerebral artery and the posterior inferior cerebellar artery, and a draining vein was the right transverse sinus.