All ETDs from UAB

Advisory Committee Chair

Edward Taub

Advisory Committee Members

Gitendra Uswatte

Victor W Mark

James E Cox

Shastry Akella

Document Type

Dissertation

Date of Award

2009

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

While attempts have been made to identify the cause and mechanism of motor deficit and subsequent recovery, there are several aspects of hemiparesis, especially in the chronic phase of acquired brain injury, that are still unclear. This study used diffusion tensor imaging (DTI) to study the role of white matter in upper extremity motor function in chronic hemiparesis, especially after administration of an efficacious therapy, Constraint-Induced Movement Therapy (CI therapy). This therapy has been proven effective in treating chronic motor deficit and has recently been associated with structural changes in the gray matter tissue in the brain. The goal of this study was to determine if DTI could identify structural brain changes in white matter of chronic stroke patients with motor deficit. In addition, a small number of patients were given CI therapy in a preliminary study to determine the relation of white matter damage to CI therapy outcome. In eighteen chronic hemiparetic patients fractional anisotropy (FA) values were calculated over the whole brain, before and after either CI therapy or comparison therapy, and tractography was utilized to isolate the CST. Results indicate that in the hemisphere contralateral to a hemiparetic limb there was a significantly reduced integrity of the white matter fibers compared to the ipsilateral hemisphere. This was not only the case before CI therapy, which was expected, but it was also the case after CI therapy treatment. CI therapy did not increase the integrity of the CST. A decrement in motor ability was found in patients with a distorted/disrupted CST. We hypothesize that the alterations in the path of the CST are indicative of a large reorganization of the brain due to the presence of lesions or hydrocephalus ex vacuo. This large scale reorganization could have interfered with the normal functioning of motor circuits. This finding may suggest that motor deficits after damage to the brain are not related to the integrity of the CST alone. The more important factor might be the strength of the entire motor circuitry in which the CST is only one participant.

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