Argye E. Hillis, MD, MS
Assistant Professor
Department of Neurology
Johns Hopkins University
School of Medicine
Assistant Professor
Department of Cognitive Science
Krieger School of Arts and Sciences
Contact information:
Argye@JHMI.edu
410-614-1575 (phone)
410-614-1746 (fax)
An estimated 390,000 stroke survivors each year have longlasting functional disabilities (National Stroke Association, 1998). Among the most common disabling conditions are impairments of naming due to dominant hemisphere stroke and hemispatial neglect due to nondominant stroke. A major effort is underway to prevent disability from stroke by intervening in the first few hours with thrombolytics or neural protective agents.
Such acute stroke interventions require medical professionals to evaluate stroke patients within hours of stroke onset to determine candidacy for tissue reperfusion or neural protection. Estimates of the size and site of infarct (e.g., cortical vs subcortical), salvageable tissue and prognosis that enter into this decision must currently extrapolate from what is known about brain-behavior correlates identified in stroke survivors with chronic disabilities.
Limitations of this approach include the facts that hypometabolic regions remote from the infarct are likely to contribute to the manifestations in early stroke and that substantial reorganization of structure-function relationships takes place days to months after stroke onset.
The proposed study utilizes the Principal Investigator's experience in speech-language pathology and cognitive neuropsychology, and clinical training in neurology, to identify brain-behavior correlates in hyperacute stroke (within 24 hours of onset), before the opportunity for reorganization. The investigation will focus on the characterization and localization of naming disorders and hemispatial neglect.
Cognitive testing in the hyperacute period, at 3 days, and at 3 months will evaluate the mental representations and processes underlying naming and spatial attention. Areas of hypometabolism, hypoperfusion, and actual infarct associated with specific impairments in these cognitive domains will be identified with new magnetic resonance imaging techniques of Perfusion Imaging and Diffusion Weighted Imaging and with follow-up conventional MRI. The correlations between acute functional impairments of specific cognitive representations and physiologic or structural lesions will be used to evaluate proposed neuronal pathways underlying naming and spatial attention. These findings will be used to predict the size and site of infarcted or hypoperfused neural tissue from cognitive impairments in hyperacute stroke, and will thus be useful in treatment decisions and prognosis. This study is funded by the National Institute on Deafness and Communication Disorders.
