DETECTION OF VERTEBROBASILAR INTRACRANIAL STENOSES - TRANSCRANIAL DOPPLER SONOGRAPHY VERSUS ANGIOGRAPHY

Vertebrobasilar intracranial stenoses seem to carry a higher risk of b rain stem ischemia than proximal vertebral artery stenoses. Our aim wa s to assess the value of transcranial Doppler sonography versus angiog raphy in detecting and quantifying these intracranial stenoses. All co nsecutive patients who underwent transcranial Doppler sonography prior to angiography from 1989 to 1994 and whose sonograms showed a stenosi s of greater than 50% of one vertebral artery (21 cases) or of the bas ilar artery (eight cases) were included in the study. These patients w ere compared with 60 other consecutive stroke patients studied via tra nscranial Doppler sonography prior to normal vertebrobasilar angiograp hy. The transcranial Doppler sonographic criteria for stenosis were a peak systolic frequency shift greater than 2 KHz. A tight stenosis was identified by this pattern combined with direct and reverse low frequ encies of high spectrum energy. The sensitivity of transcranial Dopple r sonography using a peak systolic frequency shift in diagnosing steno ses reached 80% and its specificity was 97% if only atheromatous steno ses were considered. The main diagnostic failures concerned bilateral stenoses or contralateral occlusion, tandem lesions, and upper basilar artery stenosis. Transcranial Doppler sonography underestimated the d egree of stenosis compared to angiography in 55% of the cases. We conc lude that transcranial Doppler sonography is accurate in recognizing a stenosed vessel in the intracranial vertebrobasilar circulation, but if this finding will alter therapy, the examination must be complement ed by magnetic resonance angiography.