Hemodynamic Studies in Early Ischemic Stroke

Abstract

Background and Purpose — After acute stroke, it is often standard practice to obtain magnetic resonance angiography (MRA) to seek evidence of a plausible stroke mechanism. However, hemodynamic patterns after acute ischemic stroke are variable and dynamic. We evaluated information obtained by serial transcranial Doppler ultrasonography (TCD) examinations within the first week after acute ischemic stroke and compared it with that obtained from a single MRA study. Methods — Forty-seven patients (aged 61±7 years) with acute ischemic hemispheric stroke were examined. TCD was performed within 24 hours, from 24 to 48 hours, and 4 to 8 days after ictus. Norms for TCD examination were determined in an age-matched control group that included 41 subjects without cerebrovascular disease (aged 57±10 years). Results — In 17 stroke patients, the results of initial TCD examination were normal, although TCD follow-up showed gradual deterioration of middle cerebral artery (MCA) for 1 patient with normal MRA. In 12 patients, initial TCD study and MRA showed MCA or posterior cerebral artery occlusion. Serial TCD examinations documented recanalization (6 patients), formation of a residual MCA stenosis (1 patient), or progressive deterioration of flow through a symptomatic MCA (1 patient), not evident on MRA. In 5 patients MRA was normal, but early TCD demonstrated signs of previous recanalization (transitory hyperemia, slow flow restoration). In 2 patients with MCA branch occlusion, MRA suggested occlusion but failed to document either improvement (1 patient) or deterioration (1 patient) of flow that was evident with serial TCD. In 4 patients with proximal MCA stenosis and 5 patients with internal carotid artery occlusion or stenosis, serial TCD demonstrated different patterns of collateralization and suggested dynamic collateralization patterns after stroke that were not evident on MRA. Conclusions — Serial TCD examination may reveal dynamic changes in cerebral circulation that may be missed on a single MRA study.