中、老年人突发剧烈头痛,恶心,呕吐,颈项强直,有或无意识丧失,以及腰穿脑脊液呈血性或黄变,或CT扫描显示蛛网膜下腔出血者可诊断为蛛网膜下腔出血(SAH);如无头部外伤史则称自发性SAH。引起自发SAH的原因最多是颅内动脉瘤及静脉畸形的破裂。其次是高血压脑动脉硬化的动脉破裂,及颅内肿瘤如胶质瘤、脉络膜乳头状瘤、垂体卒中、脑膜瘤、骨软骨瘤。颅内转移瘤如支气管性肺癌,绒毛膜上皮癌、恶性黑色素瘤等。再次为血液病、颅内静脉血栓形成,脑炎及脑膜 In the elderly, sudden severe headache, nausea, vomiting, neck stiffness, with or without loss of consciousness, and lumbar cerebrospinal fluid was bloody or yellowing, or CT scan showed subarachnoid hemorrhage can be diagnosed as subarachnoid hemorrhage ( SAH); If no history of head injury, spontaneous SAH. The cause of spontaneous SAH up to intracranial aneurysms and venous malformations rupture. Followed by arterial rupture of hypertensive cerebral arteriosclerosis, and intracranial tumors such as glioma, choroidal papilloma, pituitary apoplexy, meningioma, osteochondroma. Intracranial metastases such as bronchial lung cancer, choriocarcinoma, malignant melanoma and so on. Once again blood disease, intracranial venous thrombosis, encephalitis and meninges