Headache Characteristics in Subarachnoid Hemorrhage and Benign Thunderclap Headache
abstract & commentary
Synopsis: Intracranial vascular pain appears much like other visceral pain in that it is highly sensitive but lacks specificity. CT and LP remain essential tools in the acute evaluation and treatment of patients with thunderclap type headache.
Source: Linn FH, et al. J Neurol Neurosurg Psychiatr 1998;65:791-793.
The differential diagnosis of a sudden and severe headache includes aneurysmal and non-aneurysmal subarachnoid hemorrhage (SAH) and benign thunderclap headache (BTH). The ability of the clinician to distinguish what are potentially life threatening symptoms remains one of the vexing challenges in everyday practice.
In an effort to better characterize each syndrome, Linn and colleagues prospectively evaluated 102 patients referred to the emergency room for the sudden onset of severe headache with normal level of consciousness and without focal neurologic deficits. CT scans and LP were performed to confirm the presence or absence of subarachnoid blood. A detailed history was obtained by one of only two interviewers.
Linn et al established the diagnosis of aneurysmal SAH in 42 patients (41%), nonaneurysmal SAH in 23 (23%), and BTH in 37 patients (36%). In comparing the three groups, it was impossible to clearly differentiate the headache types based upon clinical criteria. Seizures in three patients (7%) and diplopia in two patients (5%) were the only two symptoms that occurred solely in the aneurysmal SAH group. Otherwise, headache severity, onset, progression, associated nausea/vomiting, and transient neurologic symptoms including change in consciousness, sensory symptoms, weakness, ataxia, and speech arrest could not distinguish benign from SAH groups. Furthermore, there was no significant difference in the SAH (37%) and BTH (57%) groups with respect to previous headache history.
Comment by jeffrey reich, MD
Previous studies have found that 25% of patients presenting with sudden, severe headache have SAH.1 In the current prospective study, it was 65%. It is important to note that abrupt onset, severe pain, and transient focal symptoms are all compatible with BTH as well. It is unclear from their study, however, whether a previous headache history and negative CT could comfortably rule out SAH and avoid the need for LP. Nonetheless, intracranial vascular pain appears much like other visceral pain in that it is highly sensitive but lacks specificity. As such, CT and LP remain essential tools in the acute evaluation and treatment of patients with thunderclap type headache. (Dr. Reich is Assistant Professor of Neurology, New York Presbyterian Hospital-Cornell Campus.)
Reference
1. Linn FH, et al. Lancet 1994;344:590-593.
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