High-intensity transient signals in patients with cerebral ischemia

Background and Purpose This study investigated the diagnostic relevance of transcranial Doppler monitoring for the detection of high-intensity transient signals (HITS) in patients with recent cerebral ischemic events of various origins. Methods We prospectively performed bilateral transcranial Doppler monitoring (mean, 48+/-8 minutes) from both middle cerebral arteries in 280 patients with an acute (<4 weeks) cerebral ischemic event in the middle cerebral artery territory and in 118 asymptomatic control subjects. HITS were analyzed according to a standardized protocol. Results Symptomatic patients had a significantly (P<.001) higher rate (9.3%) of HITS than asymptomatic control subjects (1.7%). Patients with reversible ischemia (4.2%) and patients with suspected small-vessel syndromes (4.5%) had lower rates of HITS (P<.05) than those with large-vessel territory strokes (14.2%). Brain imaging (CT/MRI) results corresponded with this observation: the occurrence of HITS was significantly higher (P<.001) in patients with a pattern of large-vessel territorial brain infarction (19.0%) than in those with lacunar lesions (0%) or unidentified ischemic lesions. (3.4%). Patients with identified sources of potential embolism (12.9%) had HITS (P<.001) more frequently than those without (0%). Patients with cardiac sources of embolism (excluding artificial heart valves) showed fewer HITS (6.2%) than patients with vascular sources (17.1%). Conclusions The results indicate that HITS occur predominantly in patients with large-vessel territory stroke patterns and persisting deficits that are most likely due to artery-to-artery or cardiogenic embolism. In contrast, patients with small-vessel disease and rapid recovery only occasionally present with HITS. Thus, the detection of HITS may substantially support the classification of the individual pathogenesis of cerebral ischemia, particularly when multiple risk constellations for stroke coexist.