正常脳脊髄液圧性水頭症（Normal Pressure Hydrocephalus）の8治験例

EIGHT CASES OF SURGICALLY TREATED NORMAL PRESSURE HYDROCEPHALUS

I．はじめに

　1965年Adamsら^1）によつて，正常脳脊髄液圧性水頭症（Normal Pressure Hydrocephalus），または，症候性潜在性水頭症（Symptomatic Occult Hydrocephalus）という概念が提唱された。これは，中年または老年患者でsenile dementiaまたはcerebral arteriosclerosisとして分類されているものの中に見出される1症候群で，Adamsらはその特徴として，1）軽度の記憶障害，思考・行動の緩慢ないしは欠乏，歩行の不安定および尿失禁，2）髄液圧200mmH₂O以下，3）全脳室系または一部脳室系の拡大，4）外科的shunting operationで髄液圧をさらに下降させると，患者の状態は劇的に改善される，などをあげている。

　われわれは本症候群のうち，1）正常の髄液圧，2）脳室拡大，および3）思考力および歩行障害，尿失禁などの不定愁訴をTriasと考えれば，本症候群を呈する疾患はAdamsらのいうごとく，単にsenile dementiaまたはcerebral arteriosclerosisに類似の疾患に限られるものでなく，もつと広範囲の疾患が本症候群を呈すると考えられる。以下自験例8例を中心に述べる。

Normal pressure hydrocephalus (symptomatic oc-cult hydrocephalus) has been established as a sym-ptom complex by Adams et al. in 1965. Since then, several reports have been published on this subject with successful surgical procedures.

In this report, eight cases of normal pressure hydrocephalus have been treated with excellent re-sults except two cases of Alzheimer's and one case of Pick's diseases by ventriculoatrial shunting opera-tion. They are ruptured aneurysm of the anterior communicating artery, brain tumors in the thalamic region and Alzheimer's disease in each two cases; head injury and Pick's disease in each one case.

Internal hydrocephalus following spontaneous sub-arachnoid hemorrhage occurs mainly in case of anterior communicating aneurysm, and less often in the internal carotid aneurysm. Middle cerebral an-eurysms rarely cause hydrocephalus. Head injury is another origin of producing such internal hydro-cephalus by means of traumatic subarachnoid he-morrhage. Internal hydrocephalus is also often produced by brain tumors in the thalamic region without demonstrable focal signs.

In cases of ruptured aneurysms and head injury complete relief, and in cases of brain tumors at least temporary relief are expected by shunting operation from auxilliary complaints such as mental confusion, incontinentia urinae and gait disturbance supposed to be derived from normal pressure hydrocephalus. Actually, one patient of the thalamic tumor is enjoy-ing his normal college life more than one year postoperatively and another one also is living nor-mally except gradual increase of left hemiparesis again more than one year.

As for the pathogenesis of normal pressure hy-drocephalus, Pascal's law in enclosed fluid system is applied by Hakim et al. (1965) and "hydraulic press effect" has been proposed for this explanation.

Moderate degree of hydrocephalus in case of ruptured aneurysm and head injury should be treated carefully especially in slight increase of CSF pres-sure. The first choice in these cases is to try dehy-drators so as to reduce CSF pressure in normal range. One such case has been successfully treated by the administration of Mannitol without further surgical procedure.

Normal pressure hydrocephalus following de-generative disorders such as Alzheimer's and Pick's diseases has been treated effectively by Appenzeller and Smith (1968). However, in our experiences with two cases of Alzheimer's and one case of Pick's disease, all of which were histologically verified, no effect has been resulted in by shunting operation.