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Functional Transcranial Doppler Ultrasound Studies of Hemodynamic Response to Pneumotactile Somatosensory Stimulation and Active Motor Tasks
Stroke is the second-leading cause of death worldwide, and the fifth-leading cause of death in the United States. The United States Food and Drug Administration has only approved two treatments for acute ischemic stroke: tissue plasminogen activator and endovascular therapy. Both treatments have significant limitations, including cost and accessibility. Somatosensory stimulation has shown promise for preventing damage during acute ischemic stroke by promoting collateral flow from unaffected arteries, resulting in reperfusion of infarcted regions of the cerebral cortex. However, the effects of somatosensory stimulation on cerebral blood flow require better characterization before clinical trials on acute stroke victims can occur, particularly the effects of combining somatosensory stimulation with the uncontrolled external stimuli and movement inherent to emergency transport and the clinical environment. This work proposes to characterize the effects of a novel stimulation modality called pneumotactile somatosensory stimulation, which creates brief, punctate pressures pulses that traverse the glabrous skin of the hand, in healthy people using functional transcranial Doppler ultrasound. This dissertation first describes a typical functional transcranial Doppler experiment. This dissertation then presents the results of a functional transcranial Doppler study examining the effects on cerebral blood flow of 1) pneumotactile somatosensory stimulation alone and 2) pneumotactile somatosensory stimulation in the presence of hand squeezing, an active motor task. The results showed statistically significant bilateral increases in cerebral blood flow velocity in response to both stimulus combinations. A statistically significant additive effect was observed on the right side when comparing between with and without hand squeeze. The greatest increase in cerebral blood flow velocity occurred at traverse velocities of 25 cm/s (without hand) and 45 cm/s (with hand).The time courses of the observed cerebral blood flow responses approximate the hemodynamic response function for the cerebral neurovascular coupling mechanism. In a clinical setting such as acute ischemic stroke, motor stimulation (e.g., patient moving arm during clinical examination) may cause additional CBFV augmentation in addition to the effects of pneumotactile somatosensory stimulation.
Hage, Benjamin D, "Functional Transcranial Doppler Ultrasound Studies of Hemodynamic Response to Pneumotactile Somatosensory Stimulation and Active Motor Tasks" (2022). ETD collection for University of Nebraska - Lincoln. AAI29166774.