TRANSCRANIAL DOPPLER IN VERTEBROBASILAR VASOSPASM AFTER SUBARACHNOID HEMORRHAGE

OBJECTIVE: The primary objective of this study was to assess the incid ence of vertebrobasilar vasospasm after subarachnoid hemorrhage (SAH) by means of transcranial Doppler ultrasonography and to evaluate the c linical significance of this phenomenon. The secondary objective was t o analyze the different factors influencing the development, the sever ity, and the duration of vertebrobasilar vasospasm. METHODS: Fifty-sev en patients with traumatic SAH and 44 patients with spontaneous SAH we re evaluated and monitored by means of transcranial Doppler ultrasonog raphy. Vasospasm of the anterior and middle cerebral arteries was defi ned by mean flow velocities (FVs) exceeding 120 cm per second and at l east three times the FV of the internal carotid artery. Vasospasm of t he basilar and vertebral arteries was defined by a mean FV exceeding 6 0 cm per second. RESULTS: Vasospasm of the anterior or middle cerebral arteries was found in 27 patients and was associated with vertebrobas ilar spasm in 20 patients. FVs in anterior circulation vessels were ne ither related to the cause of the SAH nor did they correlate with the outcome. Forty-six patients (45.5%) had FVs exceeding 60 cm per second and 25 (24.8%) had FVs exceeding 85 cm per second. In 10 of these pat ients, direct or computed tomographic angiography showed arterial narr owing involving the vertebrobasilar system, whereas in 21 more patient s, computed tomography disclosed a cerebral infarction involving the v ertebrobasilar vascular territory. Vertebral artery FVs in this group were twice that of the ipsilateral carotid artery. Vertebrobasilar vas ospasm was significantly more frequent after head injury, although it was not related to the type of intracranial lesion or the Glasgow Coma Scale score at admission. It did correlate, however, with outcome (P < 0.0001) and with the intensity of SAH (P < 0.0001). Delayed neurolog ical deterioration occurred in 14 patients and was significantly more frequent in patients with basilar artery FVs above 85 cm per second (P < 0.001). Prognosis, however, could not be reliably predicted by FVs in the basilar artery, even when an FV of 110 cm per second was chosen for prediction criterion. CONCLUSION: These results suggest that vert ebrobasilar vasospasm is more common than previously thought, especial ly in association with head injury, with which it may significantly co ntribute to brain stem ischemic lesions and therefore justify specific therapeutic measures.