Acetazolamide静脈内投与時における髄液圧変化—正常圧水頭症に対するシャント術適応の補助検査として

Changes of CSF Pressure Induced by Acetazolamide Administration Test : As an Indicator of Shunt Operation for So-Called Normal Pressure Hydrocephalus

　Acetazolamide急速静脈内投与時の髄液圧変化を測定し，その圧反応性と臨床所見，CT所見，持続髄液圧測定におけるB波の出現，シャント有効性との関連について検討した。頭部CT上脳室拡大を認め，シャント術適応決定の補助検査として腰部髄液圧測定を行った9例を対象とした。Acetazolamideの投与は500mgを生理的食塩水10 mlに溶解し，急速静脈内投与し，投与前，および投与後30分間における髄液平均圧の変動について検討した。（1）前値に対し50％以上の圧上昇を示したA群5例と，圧上昇が25％以下または無反応であったB群4例に分類された。（2）A群5例中4例においてシャント術を施行し，その全例において明らかな臨床症状の改善を認めた。（3）B群においては，臨床的に遷延性意識障害を呈した症例が多く，またCT上脳梗塞，脳内出血，頭部外傷などによる低吸収域を全例に認め，脳実質障害が病態の主因と考えられた。（4）Acetazolamide投与に対して，良好な反応性を示す症例では，持続圧測定において，B波が高頻度に出現する傾向が認められた。（5）NPH疑診例に対するAcetazolamide負荷試験の有用性が示唆された。

Lumber subarachnoid pressure was monitored via intrathecally introduced catheter in 9 patients, who showed ventricular dilatation on brain CT and were suspected of normal pressure hydrocephalus. Dur-ing the pressure measurement, 500 mg of acet-azolamide was rapidly injected intravenously and changes of CSF pressure were recorded. The results of the study were compared to clinical signs, brain CT findings and results of continuous pressure monitoring.

The types of response of CSF pressure induced by acetazolamide administration were classified into 2 groups. In 5 cases (Group A), more than 50 percent increase of CSF pressure compared to the resting value was noted. On the contrary, in the remaining 4 cases (Group B) , CSF pressure showed only slight increase (less than 25 percent or none). VP shunt was performed in 4 cases in Group A. Definite improvement of clinical symptoms was observed in all of these surgically treated cases. Correlation was found between the response to Acetazolamide administration and the appearance of B wave in the continuous spinal pressure monitoring. This study suggests that Acetazolamide test may be useful diagnostic test to select the patients for shunt opera-tion.