中脑周围非动脉瘤性蛛网膜下腔出血的影像学诊断

目的 中脑周围非动脉瘤性蛛网膜下腔出血(PNSAH)是脑血管造影(CAG)阴性的蛛网膜下腔出血(SAH)中的一种独特且预后较佳的亚型。本探讨其影像学特点和诊断。方法：回顾性分析我科连续收治的30例PNSAH。所有患均进行CT和全脑血管造影，23例进行了MR检查，25例行CT血管造影(CTA)检查。结果：CT上SAH位于脑干周围的脑池内．Fisher分级2—3级。CAG、CTA均无阳性发现，早期MR可见脑池内的出血灶，晚期MR正常。结论：PNSAH具有典型的CT表现，但CAG可明确排除其他部位出血。首次CAG和CTA检查均正常的典型患．1个月后可只行CTA而省略CAG复查。诊断PNSAH必须排除椎基底脑动脉瘤。

Imaging diagnosis of perimesencephalic non-aneurysmal subarachnoid hemorrhage

Objective To clarify the imaging characteristics and diagnosis of perimesencephalic non-aneurysmal subarachnoid hemorrhage (PNSAH) with negative cerebral angiography (CAG). Methods A retrospective analysis was performed in 30 consecutive patients with PNSAH. All the patients received computed tomography (CT) and CAG ,and of them, 23 patients and 25 patients received examination of magnetic resonance (MR) and CT angiography (CTA) respectively as well. Results All the CT scan findings revealed subarachnoid hemorrhage (SAH) located in the perimesencephlic cistern with the Fisher's grade of 2 to 3. The CAG and CTA failed to show any positive findings. MR imaging in the patients with acute phase revealed SAH in the perimesencephlic cistern and ,no any positive findings was found in patients with chronic phase. Conclusions PNSAH has a typical CT appearance. CAG continues to be the gold standard for the diagnosis of PNSAH. If the PNSAH patients with typical CT pattern have normal manifestations in their first CAG and CTA, they only need to repeat the examination of 3D-CTA in one month later. The diagnosis of PNSAH could be made after excluding the existence of the vertebro-basilar artery aneurysm.