高齢者における特発性正常圧水頭症

Idiopathic Normal Pressure Hydrocephalus in the Aged

I．はじめに

　わが国の急速な高齢者社会への進行とともに，老人の痴呆や歩行障害が重要な問題となっている．この高齢者の痴呆は脳血管性痴呆やアルツハイマー型老年性痴呆によることが多いが，時に痴呆様の精神活動の低下や歩行障害が髄液短絡術で改善する場合があり，このような例は特発性正常圧水頭症と呼ばれる．正常圧水頭症にはクモ膜下出血後や頭部外傷後にみられる続発性のものと原因不明の特発性のものとがあるが，続発性と異なり，特発性では他の痴呆疾患との鑑別が容易でなく，また，高齢者では髄液短絡術後に慢性硬膜下血腫等の合併症をきたす頻度も高いとされているので，より確実な鑑別法が望まれる．

　われわれは，従来より持続腰部髄液圧測定法を用いて各種交通性水頭症の頭蓋内圧測定を行ってきたが，本稿では高齢者の特発性正常圧水頭症の鑑別における本法の有用性について検討した．

Continuous lumbar cerebrospinal fluid pressure measurement was made in 19 cases of aged patients suspected of idiopathic normal pressure hydrocephalus. Based on the pressure study, they were divided into high pressure group (H group) and normal pressure group (N group). H group was composed of 11 cases and N group of 8 cases. Baseline pressures in H group and N group were 16.3±3.0mmHg, 9.6±1.7mmHg, re-spectively and the difference was statistically signifi-cant. Pulse pressure was high in H group and frequen-cy of pressure waves was also significantly high in H group. There were no significant differences in clinical symptoms and CT findings between the two groups, except for clinical improvement after cerebrospinal fluid removal, which was noted in all of 6 cases ex-amined in H group. No difference between them was noted on CT cisternography and cerebral blood flow measurement. Shunt surgery was carried out in the cases of H group and it was effective in 8 of 11 cases (72.7%).

Thus, continuous lumbar cerebrospinal fluid measure-ment was useful for selection of idiopathic normal pressure hydrocephalus in the aged.