広範な脊髄空洞症を合併した後頭蓋窩くも膜嚢胞の1例

A Huge Retrocerebellar Arachnoid Cyst with Syringomyelia : case report

I．はじめに

　くも膜嚢胞の発生部位として後頭蓋窩は中頭蓋窩に次ぐ．後頭蓋窩くも膜嚢胞の初発症状としてめまい，眼振，頭痛，精神発達遅延等が報告されているが，小児と成人では臨床症状にかなりの違いが認められている^2,4）．後頭蓋窩くも膜嚢胞では身体他部位における奇形合併率は20-30％であり，中枢神経系の合併奇形も30％と高い（中脳水道狭窄，脳梁欠損など）^12）．

　われわれは左下肢の脱力発作で発症し，画像上高度な水頭症と広範な脊髄空洞症を合併した巨大な後頭蓋窩くも膜嚢胞の1例を経験し，嚢胞-腹腔短絡術にて良好な結果を得たので文献的考察を含め報告する．

The authors report a case of a huge posterior fossa arachnoid cyst with syringomyelia. This 22-year-oldman presented with a history of drop attacks. Magnetic resonance imaging demonstrated ventricular hy-drocephalus, a huge posterior fossa arachnoid cyst and syringomyelia. Cyst-peritoneal shunting was instal-led. The patient had an uneventful postoperative course, and his drop attacks disappeared. Magnetic reso-nance imaging one month after surgery showed reduction of the ventricular size and size of the arachnoidcyst and syrinx.

Large arachnoid cysts in the posterior fossa are reported occasionally, but rare with syrinx. The authorsdescribed this case to illustrate the possible contribution of the pathogenesis of the syringomyelia associ-ated with a huge posterior fossa arachnoid cyst.