TRANSIENTLY INCREASED BASILAR ARTERY FLOW VELOCITY FOLLOWING SEVERE HEAD-INJURY - A TIME-COURSE TRANSCRANIAL DOPPLER STUDY

Background and Purpose. Transcranial Doppler ultrasonography has been used to study changes in cerebral hemodynamics following head injury. However, most studies evaluated the anterior circulation and little in formation exists on transcranial Doppler of the vertebrobasilar arteri es after head injury. Methods. Thirty-two patients with a Glasgow Coma Scale (GCS) score between 4-8 and 11 patients with a GCS score betwee n 9-14 were studied using transcranial Doppler ultrasonography for the first 10 days after injury. Daily variations in the mean blood flow v elocities of all major cerebral arteries were recorded. Results. In pa tients with GCS score between 4-8, the mean blood flow velocities in t he middle cerebral and basilar arteries gradually increased beginning on day 2 postinjury and peaked on the 4th-5th day after injury. Those changes were more prominent, and appeared earlier, in the basilar arte ry. The ratio between the mean flow velocities of the middle cerebral artery and the basilar artery during the first 4 days was significantl y lower than in normal controls, indicating a particular increase of f low velocity in the basilar artery. Nineteen out of 32 patients (60%) with severe head injury showed mean blood flow velocity increased over 75 cm/sec in the basilar artery. Mean blood flow velocity >90 cm/sec in the basilar artery, compatible with vasospasm, was observed in 12 o f 32 patients (37%). Spasm in the middle cerebral artery was observed in 12 (37%) of patients; 10 of them also had evidence of basilar arter y spasm. On the whole, 14 of 32 (43%) patients had evidence of spasm e ither in the middle cerebral car basilar arteries or in both. In 5 of 11 patients (50%) with moderate head injury (GCS score 9-14), blood fl ow velocity in the basilar artery greater than 75 cm/sec was observed, but in only two of them it reached the values over 90 cm/sec. Vasospa sm in the middle cerebral artery was noted in one patient. Conclusions . A significant number of patients develop increased flow velocities c ompatible with vasospasm in the basilar artery after severe head injur y. This phenomenon may represent an additional factor that contributes to the poor outcome of severely head-injured patients.