[Diagnosis and general assessment of acute subarachnoid hemorrhage]

CT is still considered the first and most important examination in the case of subarachnoid hemorrhage. Frequently the CT findings are normal and no blood is detected in the CSF spaces. If that is the case, it will be useful to reevaluate the clinical presentation and it might be indicated to enhance the diagnostic evaluation with the use of lumbar puncture and CSF exam, or recurring to the study of the spine. In other cases, CT may detect slight modifications, with small blood collection in the CSF spaces, or more important bleeding in the CSF, intracerebral or intraventricular. Angiography represents the following diagnostic step.