The Prevalence of Cerebrovascular Abnormalities Detected in Various Diagnostic Subgroups of Spontaneous Subarachnoid Hemorrhage in the Modern Era.

Objective: To determine prevalence of cerebrovascular abnormalities in diagnostic subgroups of spontaneous subarachnoid hemorrhage (SAH) in a regional neurosurgical center in the modern era.

Methods: Data of 609 consecutive patients with spontaneous SAH in a 3-year period (August 2010 to August 2013) were prospectively collected. Patients were divided into 3 diagnostic subgroups: computed tomography (CT) positive for SAH; CT negative but positive cerebrospinal fluid examination by spectrophotometry for SAH; CT negative for SAH and inconclusive cerebrospinal fluid examination. All patients fit for intervention underwent CT angiography with or without digital subtraction angiography to identify vascular abnormalities for subsequent treatment.

Results: Of 609 patients, 554 were fit for further investigation and consideration of further intervention; 514 patients had confirmed SAH. Mean patient age was 54.0 years; 61.5% of patients were women. Of patients, 390 (75.9%) showed vascular abnormalities on angiography. There were 438 patients (85.2%) with confirmed SAH diagnosed on CT scan (group 1). Vascular abnormalities were detected in 81.1% of patients; 18.9% of patients with positive CT scan had no identifiable cause of SAH. Of patients with confirmed SAH, 76 (14.8%) had negative CT scan but positive lumbar puncture (group 2); 46.1% of patients in this group had vascular abnormalities. Three patients with inconclusive cerebrospinal fluid examination had lesions requiring treatment. Median length of hospital stay in group 1 patients was longer than median length of hospital stay in group 2 patients.

Conclusions: Frequency of vascular abnormalities in spontaneous SAH is lower than the traditionally quoted figure, which has diagnostic and prognostic implications for patient management.