[Differential diagnosis of subarachnoid hemorrhage]

The diagnosis of subarachnoid haemorrhage (SAH) presents in particular cases, some difficulties, even for neurosurgeons; the possibility that CT scan is negative during the first hours post SAH, represents a further problem; for these reasons the importance of lumbar puncture is stressed. In some cases an intracerebral clot may be misunderstood like an hypertensive haemorrhage. The recognition of the so called warning leaks, preceding the 40% of cases of "major" SAH, has a great importance for improving the final results, overall if is considered the high rate of mortality in the first 48 hours post a major SAH. For these reasons a peculiar attention has to be paid to these patients by the peripheral emergency rooms.