Cerebral blood velocity in subarachnoid haemorrhage: a transcranial Doppler study.

A study examining the utility of transcranial Doppler ultrasound for the determination of cerebral vasospasm following subarachnoid haemorrhage is reported. A control group of 21 patients and a second group of 20 patients suffering from subarachnoid haemorrhage or aneurysm and a group of 26 with other intracranial pathologies were studied. The Doppler flow velocity (DFV) was significantly higher when vasospasm was present. If it was higher than 100 cm/s, the patients were found to have vasospasm in 80% of cases. If Doppler flow velocity was below 100, less than 10% had spasm. Doppler flow velocity was not found to increase following craniotomy in patients not suffering from subarachnoid haemorrhage. In subarachnoid haemorrhage patients there was a trend to increased Doppler flow velocity especially in patients who developed neurological deficit. Doppler flow velocity and Initial Slope Index by xenon clearance (ISI) were not found to correlate with clinical grade. The ISI/DFV quotient (which can be shown mathematically to be related to vessel diameter) was found to correlate well with clinical grade. In this largely post-operative group, absolute levels, or rate of change of Doppler flow velocity could not be shown to be related to the onset or existence of neurological deficit.