Isolated angiitis of the central nervous systemの2症例における血管形態と脳循環動態の経時的変化

Chronological Changes in the Vasculature and the Cerebral Blood Flow of Two Patients with Isolated Angiitis of the Central Nervous System

要旨　Isolated angiitis of the central nervous system（IAC）の2症例に対して経時的にMR angiography，SPECTを施行し，個々の病態について検討を行った。症例1は58歳女性，突然の頭痛で発症，その4日後に皮質下出血をきたした。病初期に拡張していた脳血管は狭小化へ移行し，約2カ月で回復した。脳血流は寛解期と同程度に保持され，血管径には相関しなかった。症例2は24歳女性，持続する激しい頭痛で発症。当初，末梢領域に限局していた分節状の狭窄が頭蓋内全域に広がり，約3カ月で回復した。経過中の脳血流は一貫して低値を示し，寛解期の約65％であった。前者は炎症性変化が脳実質に波及し，その結果hyperemiaを呈し脳出血の一因となったと推察した。また，後者は炎症が血管壁内に留まったため血管径と脳血流量が相関を示したものと思われる。この臨床経過の相違は，IACが多彩な病態を有する疾患群との示唆を与えるものである。

Isolated angiitis of the central nervous system（IAC） is an inflammatory, rare vasculopathy confined to the central nervous system, and the exact etiology has remained uncertain. We report serial changes in the vasculature and the mean cerebral blood flow（mCBF）in two patients with IAC.

The first patient, a 58-year-old female, had sudden onset of severe headache and CT 4 days later showed cerebral hemorrhage in the frontal lobe. MRA revealed that the main trunks were dilated on admission, whereas two weeks later, diffuse narrowing of affected arteries occurred in multiple vascular distributions. She required about two months for almost full recovery in MRA findings. Mean CBF during the period of vascular narrowing did not correlate with the form of vasculature, and was much the same as that in the chronic phase.

The second patient, a 24-year-old female, presented with severe headache one day after delivery following an uncomplicated pregnancy. MRA findings showed that, at first, segmental stenoses were located only in the peripheral regions of the middle cerebral artery, but this vascular abnormality spread to the anterior, middle and posterior cerebral arteries. She showed almost full recovery in MRA findings after about 3 months. SPECT analysis showed approximately 35％ decrease in mCBF compared with that in the chronic phase.

In the first case, hyperemia, which was caused by inflammatory cells infiltrating into the brain parenchyma through the vessel wall, contributed to cerebral hemorrhage. On the other hand, in the second case it was presumed that because inflammation was restricted to the vascular wall, mCBF consequently correlated with the form of vasculature. Our experience suggests that IAC has several etiologies.