subarachnoid hemorrhage

Also known as subarachnoid haemorrhage, SAH, subarachnoid hematoma, subarachnoid haematoma

bleeding into the subarachnoid space

Key facts

Other names: Subarachnoid haemorrhage
Pronunciation: / ˌ s ʌ b ə ˈ r æ k n ɔɪ d ˈ h ɛ m ər ɪ dʒ /
Specialty: Neurosurgery , Neurology , Emergency medicine
Symptoms: Severe headache of rapid onset , vomiting , decreased level of consciousness
Complications: Delayed cerebral ischemia , cerebral vasospasm , seizures
Types: Traumatic, spontaneous (aneurysmal, nonaneurysmal, perimesencephalic)
Causes: Head injury , cerebral aneurysm
Risk factors: High blood pressure , smoking , alcoholism , cocaine
Diagnostic method: CT scan , lumbar puncture
Differential diagnosis: Meningitis , migraine , cerebral venous sinus thrombosis
Treatment: Neurosurgery or radiologically guided interventions

Article

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consciousness, fever, weakness, numbness, and sometimes seizures. Neck stiffness or neck pain are also relatively common. In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed.

SAH may occur as a result of a head injury or spontaneously, usually from a ruptured cerebral aneurysm. Risk factors for spontaneous cases include high blood pressure, smoking, family history, alcoholism, and cocaine use. Generally, the diagnosis can be determined by a CT scan of the head if done within six hours of symptom onset. Occasionally, a lumbar puncture is also required. After confirmation further tests are usually performed to determine the underlying cause.