Background and purpose: The objective of this study was to evaluate the yield of emergent transcranial Doppler (TCD) for the evaluation of acute cerebral ischemia.
Methods: We performed urgent bedside non-contrast-enhanced TCD in patients with acute cerebral ischemia before or immediately after baseline CT scanning. A fast-track scanning protocol (</=15 minutes) and detailed diagnostic criteria were developed for portable single-channel TCD testing. TCD results were compared with angiography.
Results: Of 130 consecutive patients studied, 36 were eligible for thrombolytic therapy; 46 with ischemic strokes and 48 with transient ischemic attacks were not eligible for thrombolysis. TCD identified occlusions in 69% of thrombolysis-eligible patients, compared with 24% and 0% of patients with strokes and transient ischemic attacks, respectively, not eligible for thrombolysis (P<0.01). Stenosis was present in 17%, 33%, and 35%, and normal vessels were found in 14%, 43%, and 65% in the respective patient subgroups. TCD also identified abnormal pulsatility of flow (12 patients), abnormal flow velocities (12), microembolic signals (5), or early recanalization (5) (34 of 130; 26%). In 65% of all patients, TCD was compared with angiography (digital subtraction angiography, MR angiography, or CT angiography). Despite a 15% rate of absent temporal windows, TCD had 88% accuracy for abnormal (occlusion and stenosis) versus normal vessels: sensitivity 87.5%, specificity 88.6%, positive predictive value 87. 5%, and negative predictive value 88.6%.
Conclusions: A proximal occlusion on TCD was found in 69% of thrombolysis-eligible patients. In 26% of all patients, TCD provided further relevant information that, in addition to angiography, helped to refine the severity of a stenosis and determine stroke pathogenesis. Emergent TCD is both sensitive and specific in determining arterial occlusion and stenosis in acute cerebral ischemia.