Using Micro-Ultrasound to Investigate the Effectiveness of Short-Term Rehabilitation following Focal Ischemic Stroke

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Using Micro-Ultrasound to Investigate the Effectiveness of Short-Term Rehabilitation following Focal Ischemic Stroke

 A thesis submitted in conformity with the requirements for the degree of Master of Science Medical Biophysics University of Toronto © Copyright by Johnson Yu 2021 ii Using Micro-Ultrasound to Investigate the Effectiveness of ShortTerm Rehabilitation following Focal Ischemic Stroke Johnson Yu Master of Science Medical Biophysics University of Toronto 2021 

Abstract 

Ischemic stroke leaves 40% of survivors with moderate to severe impairment. Understanding how rehabilitation affects brain structure and function will be critical in its effective application to individual patients and in its combination with promising new interventions. In this work we investigated the impact of two weeks of skilled reaching rehabilitation on motor function, cerebrovascular tortuosity, cerebral blood flow and neuronal activity on a rodent model. Micro-ultrasound, intracerebral array electrophysiology and Montoya staircase testing were used to characterize changes in the brain and motor function following stroke. Perilesional vessels were significantly more tortuous than vessels in the contralesional cortex with a further abolishment of hypercapnia-elicited homogenization of microbubble velocities in perilesional arterioles. Rehabilitation significantly improved skilled reaching and elevated neuronal power ratios. This current project highlights functional motor recovery and neuronal plasticity in the subacute stage following stroke in the absence of cerebrovascular changes using a dual imaging modality setup.