正常脳圧水頭症—診断とshunt手術の適応

NORMAL-PRESSURE HYDROCEPHALUS : DIAGNOSIS AND INDICATION FOR SHUNT SURGERY

I．はじめに

　1965年Hakim，Adamsら^1,7）によつて提唱された，Normal pressure hydrocephalus症候群（NPH）について，その後数多くの研究，報告がある。治療可能な痴呆として多大の注目を集めてきたが，shunt手術によつて治らない例（NPH様症候群とも呼ぶべき）も多くあることが見い出され，shunt手術をする前に予めその効果を予測できるものはないかということが問題となつた。

　DiChiroらによつて開発されたRadio-isotope cister—nography （RIC）^6,13）が，脳脊髄液（CSF）の循環動態を知る上で最もよい方法であることが多くの人の認めるところとなつた。しかしこのRICにてCSFの吸収障害，ventricular stasisが認められても，shunt手術の効果がない例もあることも判明してきた^10,13）。最近ではむしろ決定的な方法はないというのが多くの人の述べる^{10,13，14,21,22）}ところとなつている。われわれもAdamsらの報告以来多数のNPH様症候群に対して，種々の検査，治療を行つてきた。これらをretrospectiveに検討し，shunt手術の適応と効果について述べる。

Clinical features and radiological findings were analyzed retrospectively after shunt surgery in 141 patients with"normal pressure"hydrocephalus (NPH). Results were summarized as follows:

1) Shunt surgeries were performed in 6 cases of 8 patients with NPH after cerebral trauma, men-ingitis or multiple infarctions. Three of them showed moderate effects after shunt surgery, but other three patients who had been severely injured and suffered for long time more than 4 months did not show any improvement.

2) One hundred and ten paients of 133 NPH patients following subarachnoid hemorrhage (SAH) were shunted. Thirty patients of 35 who had ventricular drainage in acute stage of SAH needed shunt surgery subsequently.

3) Remarkable effects were obtained after shunt surgery in 25 cases, moderate effects, in 32 cases and no effects, in 23 cases. In 18 cases shunt surgery was not indicated after clinical and radio-logical evaluation because of the lack of clinical triad and/or inclining to improvement during in-vestigation.

4) Radio-isotope cisternography (RIC) was per-formed in 86 patients. We found ventricular stasis of isotope in 16 cases (73%) of 22 patients who showed no improvements after shunt surgery. RIC was proved to demonstrate the CSF dynamics and disturbance of the CSF absorption, however it did not predict the efficacy of shunt surgery.

5) CT scans were performed in 60 patients. Most of patients whose ventricles were enlarged in slight grade without periventricular lucency (PVL) were found to be necessiated of no shunts subsequently. In patients who showed obvious brain atrophy in CT scans no effects were observed after shunt surgery, however we could not differentiate those who will benefit from shunting by the degree of ventricular dilatation and/or presence of PVL in the CT scans.

6) Sites of ruptured aneurysms did not correlate with improvement after shunt. On the clinical features, the candidates most likely to improve after shunt surgery seem to be the patients in whom, (1) the interval from SAH to shunt surgery is not so long enough 6 months, (2) the age is not so high, (3) severe primary brain damage is not demonstrated in CT scans, and (4) typical clinical symptoms of NPH are present.