TRANSCRANIAL DOPPLER DETECTION OF VERTEBROBASILAR VASOSPASM FOLLOWINGSUBARACHNOID HEMORRHAGE

Background and Purpose Transcranial Doppler sonotraphy is of establish ed value in the detection and monitoring of middle cerebral artery vas ospasm. Little information exists on the utility of transcranial Doppl er for detection of posterior circulation vasospasm. Methods Cerebral angiography and conventional handheld transcranial Doppler sonography were compared to determine sensitivity and specificity of transcranial Doppler for detection of vertebral and basilar artery vasospasm. Resu lts Of 59 consecutive subarachnoid hemorrhage patients with transcrani al Doppler angiogram correlations, 42 underwent posterior circulation angiography to evaluate 64 vertebral arteries and 42 basilar arteries during the period of risk for vasospasm and had technically adequate t ranscranial Doppler examinations within 24 hours of the angiogram. A m ean flow velocity of 60 cm/s and above was indicative of both vertebra l and basilar artery vasospasm. For the vertebral artery, there were 7 true-positive test results, 42 true-negatives, 6 false-positives (unk nown cause in 3, increased collateral flow in 1, adjacent vessel vasos pasm in 1, hyperperfusion in 1), and 9 false-negatives (anatomic in 7, operator error in 2). Sensitivity was 44% and specificity was 87.5%. For the basilar artery, there were 10 true-positives, 23 true-negative s, 6 false-positives (unknown cause in 4, hyperemia/hyperperfusion in 1, increased collateral flow in 1), and 3 false-negatives (operator er ror in 2, tortuous vessel course in 1). Sensitivity was 76.9% and spec ificity was 79.3%. When the diagnostic criterion was changed to greate r than or equal to 80 cm/s (vertebral artery) and greater than or equa l to 95 cm/s (basilar artery), all false-positive results were elimina ted (specificity and positive predictive value, 100%). Conclusions Our data suggest that transcranial Doppler has good specificity for the d etection of vertebral artery vasospasm and good sensitivity and specif icity for the detection of basilar artery vasospasm. Transcranial Dopp ler is highly specific (100%) for vertebral and basilar artery vasospa sm when flow velocities are greater than or equal to 80 and greater th an or equal to 95 cm/s, respectively.