Acute headache of recent onset and subarachnoid hemorrhage: a prospective study.

Twenty-seven patients with acute severe headache of recent onset were prospectively recruited in the Emergency Room. Mean duration of headache was 61 hours. CT scan disclosed subarachnoid bleeding in 4 patients and spinal tap revealed subarachnoid hemorrhage (SAH) in 5 patients with normal CT scan. In most SAH cases pain was bilateral, very intense and involving the occipital region. Four of these patients had doubtful or no nuchal rigidity and in one, pain improved while in the Emergency Room. In every case with an intense acute severe headache of recent onset CT scan and (if normal) a lumbar puncture are warranted to help rule out a SAH.