Distinguishing Characteristics of Headache in Nontraumatic Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a life-threatening emergency that is frequently missed due to its varied and often subtle presentation. The most common presentation of SAH is with a severe headache. The classical adjective used in SAH is "thunderclap"; however, this has not been well defined in the literature, rendering it a challenge to triage patients in clinical practice presenting with severe headache.

We undertook a prospective, observational study at a tertiary academic medical center examining the clinical characteristics of the presenting headache in SAH. We enrolled patients through the emergency department and from the neurosciences intensive care unit, and documented clinical features of the headache including the time to peak intensity, location, associated symptoms, and activities that caused worsening.

One hundred and fifty-eight subjects were enrolled, of whom 20 patients had SAH and 138 did not. Notable distinguishing features on history included occipital location (55% in the SAH group vs 22% in the non-SAH group, P < .001), "stabbing" quality (35% in the SAH group vs 5% in the non-SAH group, P < .001), presence of prior headache (50% in the SAH group vs 83% in the non-SAH group, P = .002), and associated meningismus (80% in the SAH group and 42% in the non-SAH group, P = .002). Sixty-five percent of patients with SAH reported that their headache peaked within 1 second of onset, compared with only 10% of those without SAH (P < .001).

This is the first study that has sought to examine in detail the clinical characteristics of the presenting headache in SAH. Our study suggests that the clinical features of headache with SAH are distinct from those associated with other headache syndromes, and that this may prove useful in the acute care setting in triaging patients with a chief complaint of headache.