General description

Subarachnoid hemorrhage (SAH) is a type of intracranial hemorrhage characterized by bleeding into the subarachnoid space, located between the arachnoid membrane and the pia mater surrounding the brain.

Common symptoms include a sudden, severe headache, often described as a "thunderclap headache," which is the worst headache of the patient’s life. Additional symptoms may include vomiting, decreased consciousness, fever, weakness, numbness, and seizures. Neck stiffness or pain is also frequently observed.

In many cases, SAH is associated with photophobia and meningism. Focal neurological deficits may develop either simultaneously with the headache or shortly thereafter. Approximately half of patients experience collapse or a temporary loss of consciousness, even if they later regain consciousness and recover well. Additionally, a small, self-resolving bleed may occur within a month prior to a larger hemorrhage in about 25% of cases, serving as a potential warning sign.