Small, unruptured aneurysms are asymptomatic. Symptoms of intracranial aneurysms are divided into three categories: (1) Intracranial hemorrhage: Most patients have simple subarachnoid hemorrhage, which manifests as sudden headache, vomiting, impaired consciousness, epileptic-like seizures and signs of meningeal irritation. (2) Focal symptoms: Large aneurysms often produce compression symptoms, hemiparesis, actinic nerve palsy and obstructive hydrocephalus. (3) Cerebral ischemia and cerebral artery spasm: Patients may have varying degrees of neurological dysfunction, hemiparesis, aphasia, profound and superficial sensory loss, blindness, and psychiatric symptoms. Cerebral angiography is required to confirm the diagnosis of intracranial aneurysm. Cerebral angiography should be performed in any patient with subarachnoid hemorrhage, spontaneous III-IV cranial nerve palsy or posterior group cranial nerve disorder.