円蓋部くも膜下出血の原因として脳アミロイドアンギオパチーと頸部内頸動脈狭窄症の鑑別に苦慮した1例

抄録

Cerebral amyloid angiopathy (CAA) and reversible cerebral vasoconstriction syndrome (RCVS) are well known as the cause of convexity subarachnoid hemorrhage (cSAH), and CAA is the most common cause, especially in the elderly. On the other hand, there are a few reports of cSAH caused by vascular stenosis. In this case, we had difficulty differentiating CAA from cervical internal carotid artery stenosis as a cause of cSAH.

A 78-year-old man presented with repeated attacks of weakness in the right upper limb. CT showed a cSAH in the left cerebral hemisphere and MR imaging showed an acute ischemic lesion on the left side as well as the hemorrhage. CT angiography showed severe stenosis of the left cervical internal carotid artery. After admission, we started treatment with antiplatelet drug therapy, but the patient still had repeated attacks of weakness. The symptoms were disappeared after starting antiepileptic drug, therefore possibility of partial epilepsy due to cSAH was considered as a cause of symptoms.

Only a few studies have reported cSAH secondary to vascular stenosis, and there is no consensus on its mechanism. A possible one is the disruption of collateral anastomosis, similar to the pathogenesis of moyamoya disease, and the effects of stress due to acute hemodynamic changes. On the other hand, patients with CAA may present with transient focal neurologic symptoms caused by cSAH. Both should be noted because of the similarity of their symptoms.