Critical increase of blood flow velocities after subarachnoid haemorrhage: vasospasm versus hyperaemia.

Thirty cases of subarachnoid haemorrhage (SAH), who underwent early aneurysm clipping, were studied to clarify the significance of a critical increase of blood flow velocities in correlation to neurological disability and cerebral blood flow. Three different groups of patients could be distinguished: 57% (17) of the cases showed increased TCD-values at the affected side corresponding to secondary neurological deficits (Vasospasm-group). The CBF-results pointed out a side difference according to the flow acceleration. In 7 patients (23%) we detected a similar side difference in blood flow velocity, but no secondary deficit appeared. The corresponding CBF-measurements showed risen values with no side difference (Hyperaemia-group). The third group of patients (20% i.e.6 cases) developed neurological deficits and corresponding side difference in CBF-measurements, but the transcranial Doppler sonography could not detect a significant side difference and even showed normal values (Blind-TCD-group). Critical increased blood flow velocities after SAH without secondary neurological deficits does not indicate vasospasm but hyperaemia.