A 35-year-old previously healthy woman suddenly develops a severe headache while lifting weights. A minute later she has transient loss of consciousness. She awakes with vomiting and a continued headache. She describes the headache as “the worst headache of my life.” She appears uncomfortable and vomits during your physical examination. Blood pressure is 140/85, pulse rate is 100/minute, respirations are 18/minute, and temperature is 36.8°C (98.2°F). There is neck stiffness. Physical examination, including careful cranial nerve and deep tendon reflex testing, is otherwise normal.
Which of the following is the best next step in evaluation?A) CT scan without contrast
An excruciating headache with syncope requires evaluation for subarachnoid hemorrhage (SAH). This occurs with rupture of an intracranial aneurysm, usually located at an arterial bifurcation in the anterior cerebral circulation. Rupture may occur spontaneously or at times of exercise. About 2% of persons have these aneurysms, and about one-fifth of these have multiple aneurysms. Fortunately only a small percentage of these persons ever experience rupture, which may be fatal. The headache that precedes or accompanies SAH is severe and often described as a “thunderclap” headache, meaning that it reaches its maximum intensity in seconds. Migraine may also cause severe headache, but usually reaches maximum intensity in 5 to 30 minutes. Syncope occurs in about one-half of patients with SAH and is thought to be due to accompanying cerebral artery spasm. Blood in the cerebrospinal fluid tends to irritate the meninges and may cause neck stiffness. Suspected subarachnoid hemorrhage mandates CT scanning as the initial test. In about 90% of patients, there will be enough blood to be visualized on a noncontrast CT scan. A contrast CT scan sometimes obscures the diagnosis because, in an enhanced scan, normal arteries may be mistaken for subarachnoid blood. If the CT scan is normal, a lumbar puncture will establish the diagnosis by demonstrating blood in the cerebrospinal fluid (CSF). As opposed to CSF blood from a traumatic lumbar puncture, the CSF blood does not clear with continued collection of fluid. Cerebral angiography is usually done to assess the need for surgery and to detect other aneurysms, but it is usually delayed because angiography may precipitate spasm, especially if performed right after the acute rupture. Holter monitor might be helpful in unexplained syncope but would not address the severe headache. Electroencephalography is sometimes used to diagnose seizures in a patient with unwitnessed and unexplained syncope, but would not be appropriate until subarachnoid hemorrhage has been excluded.