Initial misdiagnosis and outcome after subarachnoid hemorrhage

Mortality and morbidity can be reduced if aneurysmal subarachnoid hemorrhage (SAH) is treated urgently.

To determine the association of initial misdiagnosis and outcome after SAH.

Inception cohort of 482 SAH patients admitted to a tertiary care urban hospital between August 1996 and August 2001.

Misdiagnosis was defined as failure to correctly diagnose SAH at a patient's initial contact with a medical professional. Functional outcome was assessed at 3 and 12 months with the modified Rankin Scale; quality of life (QOL), with the Sickness Impact Profile.

Fifty-six patients (12%) were initially misdiagnosed, including 42 of 221 (19%) of those with normal mental status at first contact. Migraine or tension headache (36%) was the most common incorrect diagnosis, and failure to obtain a computed tomography (CT) scan was the most common diagnostic error (73%). Neurologic complications occurred in 22 patients (39%) before they were correctly diagnosed, including 12 patients (21%) who experienced rebleeding. Normal mental status, small SAH volume, and right-sided aneurysm location were independently associated with misdiagnosis. Among patients with normal mental status at first contact, misdiagnosis was associated with worse QOL at 3 months and an increased risk of death or severe disability at 12 months.

In this study, misdiagnosis of SAH occurred in 12% of patients and was associated with a smaller hemorrhage and normal mental status. Among individuals who initially present in good condition, misdiagnosis is associated with increased mortality and morbidity. A low threshold for CT scanning of patients with mild symptoms that are suggestive of SAH may reduce the frequency of misdiagnosis.