Idiopathic subarachnoid hemorrhage: a multicentre series of 220 patients.

BACKGROUND. The Spanish neurosurgical society created a multicentre data base on spontaneous SAH to analyze the real problematic of this disease in our country. This paper focuses on the group of patients with idiopathic SAH (ISAH). METHODS. 16 participant hospitals collect their spontaneous SAH cases in a common data base shared in the internet through a secured web page, considering clinical, radiological, evolution and outcome variables. The 220 ISAH cases collected from November 2004 to November 2007 were statistically analyzed as a whole and divided into 3 subgroups depending on the CT blood pattern (aneurysmal, perimesencephalic, or normal). RESULTS. The 220 ISAH patients constitute 19% of all 1149 spontaneous SAH collected in the study period. In 46,8% of ISAH the blood CT pattern was aneurysmal, which was related to older age, worse clinical condition, higher Fisher grade, more hydrocephalus and worse outcome, compared to perimesencephalic (42.7%) or normal CT (10.4%) pattern. Once surpassed the acute phase, outcome of ISAH patients is similarly good in all 3 ISAH subgroups, significantly better as a whole compared to aneurysmal SAH patients. The only variable related to outcome in ISAH after a logistic regression analysis was the admission clinical grade. CONCLUSIONS. ISAH percentage of spontaneous SAH is diminishing in Spain. Classification of ISAH cases depending on the blood CT pattern is important to differentiate higher risk groups although complications are not negligible in any of the ISAH subgroups. Neurological status on admission is the single most valuable prognostic factor for outcome in ISAH patients.