Negative angiography subarachnoid hemorrhage, also known as idiopathic subarachnoid hemorrhage (iSAH), is a challenging pathologic condition whose evolution and final outcome is difficult to predict with certainty. This article describes the clinical features, the type of complications and rates, as well as the final outcome of patients with iSAH.Methods
A prospective evaluation of patients with SAH was performed. Patients with a diagnosis of iSAH were included. Demographic data, clinical features, complication rates, and functional outcomes were all collected. iSAH cases were subsequently compared with patients with aneurysmal SAH (aSAH) taken from the same period.Results
Forty-nine patients fulfilled the criteria for iSAH. Patients with aSAH presented with a worse clinical condition and had a larger amount of blood in the initial computed tomography (CT) scan than iSAH patients. There were no differences in the incidence of acute hydrocephalus, and there was a positive correlation with the Fisher score and the initial clinical status in both groups. Vasospasm was more frequent among patients with aSAH, but the relationship between the incidence of vasospasm and the amount of blood in the initial CT scan was not linear. Good functional outcome was present in > 90% of iSAH patients.Conclusions
Although iSAH generally has a good prognosis, it may be accompanied with serious complications. The incidence of acute hydrocephalus in iSAH is similar to that in aSAH. There is a lower incidence of vasospasm in iSAH than aSAH. A different relationship seems to exist between these complications and the amount of blood in the CT scan.