Mechanisms of Upper-Extremity Motor Recovery in Post-stroke Hemiparesis

The results of this study will provide sound, scientific evidence of physiologic mechanisms responsible for upper-extremity weakness; evidence of the processes involved in neuromuscular adaptation; and will elucidate the relationship between impairment and motor disability in post-stroke hemiparesis.

This proposal extends the work accomplished in our initial study (project #B2405R, 'Effects of Strength Training on Upper-limb Function in Post-stroke Hemiparesis'). In the present study we will conduct a double-blind, randomized clinical trial of staged rehabilitation for the upper-extremity involving sequential delivery of functional therapy and high intensity resistance training. Therefore, this proposal directly compares the effects of functional and resistance training delivered individually. The researchers' previous work investigated a hybrid therapy of functional and resistance training against functional training alone. All subjects will participate in a 5 week run-in period of no treatment. This no-treatment block will afford multiple baseline measurements and, in addition, will provide information regarding the rate and magnitude of any spontaneous recovery without treatment. Following the second baseline measurement, all subjects will be randomized to upper-extremity rehabilitation in either: Order A - 10 weeks of functional task practice training (FTP) followed by 10 weeks of high-intensity resistance training (Power) or Order B - resistance training (Power) followed by FTP. Re-evaluation will occur following each block of treatment,and retention effects will be evaluated after 6 and 12 months with no additional treatment. Subjects will be evaluated with: outcome measures used broadly in Clinical Neurology and Rehabilitation, a battery of biomechanical performance measures including: strength, muscle activation, reflex modulation, and motor coordination, and with kinematics of free reaching movements. The researchers will investigate persons in the intermediate phase of recovery which they define as between 6 and 18 months post-stroke , having completed all inpatient and outpatient therapies, with remaining residual motor deficits.

biomechanics, Cerebrovascular Accident, electromyography, muscular weakness, recovery of function, reflex variability stroke, upper-extremity kinematics

FTP: 30 sessions (90 minute sessions, 3 times per week, 10 weeks) followed by POWER: 30 sessions (90 minute sessions, 3 times per week, 10 weeks)

POWER: 30 sessions (90 minute sessions, 3 times per week, 10 weeks) followed by FTP: 30 sessions (90 minute sessions, 3 times per week, 10 weeks)

Following an initial testing session, you will complete a 5 week no training period. At the end of this period you will then participate in a 20 week therapy program - 10 weeks of Functional Task Practice (FTP) followed by 10 weeks of Power training (dynamic resistance exercise). Each 10 week block has 30 therapy sessions for a total of 60 sessions, each lasting approximately 1-1/2 hours. Follow up evaluations will be scheduled at 6 months and 12 months after completion of the entire 20 week therapy program.

Following an initial testing session, you will complete a 5 week no training period. At the end of this period you will then participate in a 20 week therapy program - 10 weeks of Power training (dynamic resistance exercise) followed by 10 weeks of Functional Task Practice (FTP). Each 10 week block has 30 therapy sessions for a total of 60 sessions, each lasting approximately 1-1/2 hours. Follow up evaluations will be scheduled at 6 months and 12 months after completion of the entire 20 week therapy program.

Distance (in cm) of trunk lean while performing reach-to-grasp. This information is obtained from kinematics/3D motion capture and is used to inform regarding compensatory use of the trunk as compared to active motion of the shoulder, elbow, wrist, and hand, during reach-to-grasp. Change scores are expressed relative to baseline.

joint range of motion obtained using kinematics / motion capture. Change scores expressed relative to baseline.

joint range of motion obtained using kinematics / motion capture. Change scores are expressed relative to baseline.

The Fugl-Meyer Motor Assessment is a standardized scale used to measure the magnitude of motor impairment (severity) following stroke. There are separate sub-scales for the upper and lower extremities. Here we used the upper-extremity component; the full range of the scale is 0 - 66 points. Higher scores approaching 66 represent better, and lower scores approaching 0 worse, motor function. There is a significant ceiling effect with the FMA, thus a score of 66 points does not mean an individual with stroke has fully recovered. Data are change scores expressed relative to baseline.

peak velocity of movement (cm/s) during reach-to-grasp, obtained using kinematics/motion capture. Data are change scores expressed relative to baseline.

Measure is derived from kinematics/motion analysis. RPR = ratio of actual reach trajectory relative to an idealized straight line. Data are change scores, expressed relative to baseline.

Movement smoothness is determined by assessing the number of sub movements (i.e., starts and stops) that can be identified during performance of a task. Here the task was reach-to-grasp. Sub movement are identified from kinematics/3D motion analysis. Sub-movements represent discontinuities or "jerky" movements. For example, skilled reaching is smooth and may reveal a single movement unit; in contrast, unskilled movements will reveal multiple movement units (i.e., starts and stops). As a performer practices and learns the movement, the number of sub movements is reduced. Sub movements can also present in persons with pathology. The unit of sub movements is whole numbers, or counts, of the sub movements. Data are change scores, expressed relative to baseline.

Inclusion Criteria: Clinical diagnosis of cerebrovascular accident Single event Unilateral hemiplegia Between 6 months and 18 months post-event Impairment of upper-extremity function Ability to produce partial range of motion out of plane of gravity at shoulder, elbow, and wrist At least 10 degrees of wrist motion (any 10 degrees), and finger flexion/extension in 2 fingers Cognitive ability to follow 3-step commands Exclusion Criteria: Unstable or uncontrolled blood pressure Uncontrolled seizures Flaccid hemiplegia Severe cognitive impairment

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Phadke CP, Robertson CT, Condliffe EG, Patten C. Upper-extremity H-reflex measurement post-stroke: reliability and inter-limb differences. Clin Neurophysiol. 2012 Aug;123(8):1606-15. doi: 10.1016/j.clinph.2011.12.012. Epub 2012 Jan 23.

Phadke CP, Robertson CT, Patten C. Upper-extremity spinal reflex inhibition is reproducible and strongly related to grip force poststroke. Int J Neurosci. 2015 Jun;125(6):441-8. doi: 10.3109/00207454.2014.946990. Epub 2014 Sep 3.