Thunderclap headaches

In 1986, Day and Raskin described a 42-year-old woman with three episodes of intense headache of sudden onset. Although the CT scan was normal and lumbar puncture revealed bloodless, clear CSF, an arteriogram demonstrated an unruptured right internal carotid artery saccular aneurysm. They postulated that hemorrhage into the wall of the aneurysm could be the cause of her "thunderclap headaches." After spending 4 hours reviewing dictionary definitions trying to find the best adjective, Day and Raskin coined the term "thunderclap headache" to describe an intense acute headache with peak intensity at onset (Raskin, Personal communication, 1995). This study raised the disturbing prospect that a normal CT scan and CSF examination were not enough to totally exclude an aneurysmal cause of thunderclap headache.

Wijdicks et al (1988) performed a long-term follow-up study for an average of 3.3 years of 71 patients who presented with a thunderclap headache and were found to have normal CT scan and CSF examinations. Seventeen percent of the group had identical recurrences without evidence of SAH. Forty-four percent developed regular episodes of tension or migraine headaches after the thunderclap headache. The researchers suggested that the finding of an unruptured aneurysm, as in the case of Day and Raskin, was merely an incidental finding and did not justify performing cerebral arteriograms in patients with a thunderclap headache who have a normal CT scan and CSF examination. If cerebral vasospasm is seen, it could be attributed to migraine (Wijdicks et al, 1988).

Based on two patients with thunderclap headaches and normal neurologic and CT scan examination who were found to have unruptured saccular aneurysms, Hughes (1992) suggests that aneurysmal expansion could be responsible for the headache. Based on a retrospective series of 111 patients with unruptured aneurysms, Raps et al (1993) suggest that aneurysmal mechanisms of thunderclap headache include aneurysmal expansion, thrombosis, and intramural hemorrhage.

Slivka and Philbrook (1995) described four patients with thunderclap headaches without evidence of SAH who were found to have diffuse segmental cerebral vasoconstriction on cerebral arteriography. They suggest that thunderclap headache is a distinct headache category that may present with or without neurologic signs or aneurysm. The significance of the cerebral vasospasm in patients without aneurysms or SAH described on these various studies is still not certain. Migraine and vasculitis are possibilities.

The current evidence suggests that only a very small percentage of patients with thunderclap headache and normal neurologic, CT scan, and CSF examinations have unruptured aneurysms or cerebral vasospasm. In such cases, the clinician may wish to consider obtaining a MR angiogram as a noninvasive alternative to a cerebral arteriogram (Raps et al. 1993, 1994; Slivka, 1995).
 

 

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