慢性硬膜下血腫症例にみられる小脳周囲髄液腔（Pericerebellar Fluid Space）の拡張について

Dilated Pericerebellar Fluid Space in Patients with Chronic Subdural Hematoma

I．はじめに

　従来あまり注目されていないが，慢性硬膜下血腫（CSDH）の症例で，CT上小脳周囲に髄液腔（pericere—bellar fluid space＝PCFS）の拡張が認められることは稀ではない^3）．

　そこでわれわれは手術で確認されたCSDH症例を対象にPCFS拡張の頻度や他因子との関係について検討したので考察を加えて報告する．

It is not uncommon to observe the dilatation of the pericerebellar fluid space (PCFS) on CT in patients with chronic subdural hematoma (CSDH). CT scans of 92 patients with CSDH proven by surgery were re-viewed with respect to the dilatation of PCFS and we evaluated the incidence of dilated PCFS and the rela-tionship between PCFS and other factors. There were 68 males and 24 females. Patients ranged in age from 20 to 90 years (mean 65.2 years). Another 50 patients without CSDH were also reviewed as a control group. A new PCFS grading based on the CT findings was proposed, divided into 3 grades as follows. In grade 0, no PCFS could be seen on CT scans. In grade 1, PCFS could be detected along the posterior aspect of the pet-rous pyramid, and in grade 2, PCFS could be seen not only along the posterior aspect of the petrous pyramid but also under the tentorium cerebelli. The dilatation of PCFS was seen in 78 patients (84.8%) out of the 92 cases. In 50 patients without CSDH (control group), the dilatation of PCFS was noted only in 6 (12%). The dilatation of PCFS was almost always seen on the same side as the CSDH. Among many factors, the sig-nificant factor was the degree of the midline shift, the bigger the midline shift caused by CSDH, the larger was the dilated PCFS. Although the mechanism of the dilated PCFS in patients with CSDH is not clear, it is postulated that the mechanism is caused by CSF flow disturbance, compression or adhesion of the subarach-noid space due to CSDH. It should be emphasized that recognition of the dilated PCFS is a clue to make early diagnosis of CSDH, and is useful for better understand-ing of the pathogenesis of CSDH and CSF circulation.