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Basilar artery vasospasm after severe head injury: a preliminary transcranial Doppler ultrasound study
1Department of Neurosurgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
Background:
Post-traumatic vasospasm after severe head injury is now a well known entity. However, all studies available in the literature have evaluated only the anterior cerebral circulation. We evaluated the incidence of basilar artery vasospasm in patients with severe head injury.
Methods:
Basilar artery mean blood flow velocity was measured in 16 patients with severe closed head injury (Glasgow Coma Scale 8 or less) using transcranial Doppler ultrasonography. Ten normal subjects also underwent the same investigation. The patients' age ranged from 5 to 65 years. The study group included 13 males and 3 females. All patients underwent serial CT scans. In 10 patients the blood flow velocity was measured within 72 hours of the injury and in the remaining 6 it was done within 4 days to 3 weeks after the injury.
Results:
The basilar artery could be insonated easily in all the patients. The depth of insonation ranged from 65-85 mm in adults and 50-60 mm in children (n = 2). The mean blood flow velocity in severely head-injured patients was 47.4 cm/second which was significantly higher than the normal value of 42 cm/second (p < 0.008). Eight of the 14 adults (57%) had a mean blood flow velocity higher than the control value. In 7 (50%) of these the velocity was higher than 60 cm/second. Seven of these 8 patients with a high blood flow velocity had evidence of diffuse brain injury on CT scan. Six of them had effacement of the basal cisterns as a result of diffuse brain oedema. Among the remaining 8 patients who had contusion and haematoma on CT scan, only 2 had a high blood flow velocity in the basilar artery.
Conclusion:
Basilar artery blood flow velocity is higher in patients with severe head injury. Patients with diffuse brain injury have a particularly high velocity. Thus, it may be an easy method to assess the severity of head injury. The temporal profile of basilar artery vasospasm needs to be established in severely head-injured patients to assess its clinical utility.