Initial loss of consciousness and risk of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

Abstract

Delayed cerebral ischemia (DCI) is a major cause of death and disability in patients with aneurysmal subarachnoid hemorrhage. We studied the prognostic value for DCI of 2 factors: the duration of unconsciousness after the hemorrhage and the presence of risk factors for atherosclerosis. In 125 consecutive patients admitted within 4 days after hemorrhage, we assessed the presence and duration of unconsciousness after the hemorrhage, the neurological condition on admission, the amount of subarachnoid blood, the size of the ventricles, and a history of smoking, hypertension, stroke, or myocardial infarction. The relationship between these variables and the development of DCI was analyzed by means of the Cox proportional hazards model. The univariate hazard ratio (HR) for the development of DCI in patients who had lost consciousness for >1 hour was 6.0 (95% CI 3.0 to 12.0) compared with patients who had no loss or a <1-hour loss of consciousness. The presence of any risk factor for atherosclerosis yielded an HR of 1.4 (95% CI 0.6 to 3.5). The HR for unconsciousness remained essentially the same after adjustment for other risk factors for DCI. The HR for a poor World Federation of Neurological Surgeons score (grade IV or V) on admission was 2.9 (95% CI 1.5 to 5. 5); that for a large amount of subarachnoid blood on CT was 3.4 (95% CI 1.6 to 7.3). The duration of unconsciousness after subarachnoid hemorrhage is a strong predictor for the occurrence of DCI. This observation may contribute to a better understanding of the pathogenesis of DCI and increased attention for patients at risk.