Kathye E. Light

Chronic Motor Dysfunction After Stroke Recovering Wrist and Finger Extension by Electromyography-Triggered Neuromuscular Stimulation

BACKGROUND AND PURPOSE After stroke, many individuals have chronic unilateral motor dysfunction in the upper extremity that severely limits their functional movement control. The purpose of this study was to determine the effect of electromyography-triggered neuromuscular electrical stimulation on the wrist and finger extension muscles in individuals who had a stroke > or = 1 year earlier. METHODS Eleven individuals volunteered to participate and were randomly assigned to either the electromyography-triggered neuromuscular stimulation experimental group (7 subjects) or the control group (4 subjects). After completing a pretest involving 5 motor capability tests, the poststroke subjects completed 12 treatment sessions (30 minutes each) according to group assignments. Once the control subjects completed 12 sessions attempting wrist and finger extension without any external assistance and were posttested, they were then given 12 sessions of the rehabilitation treatment. RESULTS The Box and Block test and the force-generation task (sustained muscular contraction) revealed significant findings (P<0. 05). The experimental group moved significantly more blocks and displayed a higher isometric force impulse after the rehabilitation treatment. CONCLUSIONS Two lines of evidence clearly support the use of the electromyography-triggered neuromuscular electrical stimulation treatment to rehabilitate wrist and finger extension movements of hemiparetic individuals > or =1 year after stroke. The treatment program decreased motor dysfunction and improved the motor capabilities in this group of poststroke individuals.

Reliability of motor cortex transcranial magnetic stimulation in four muscle representations

OBJECTIVE Motor cortex plasticity may underlie motor recovery after stroke. Numerous studies have used transcranial magnetic stimulation (TMS) to investigate motor system plasticity. However, research on the reliability of TMS measures of motor cortex organization and excitability is limited. We sought to test the reliability of these TMS measurements. METHODS Twenty healthy volunteers were tested twice over a two-week period using TMS to determine motor threshold, map topography, and stimulus-response curves for first dorsal interosseous (FDI), abductor pollicis brevis (APB), extensor digitorum communis (EDC), and flexor carpi radialis (FCR) muscles. RESULTS We found moderate to good test-retest reliability TMS measurements of motor threshold (ICC=0.90-0.97), map area (ICC=0.63-0.86) and location (ICC=0.69-0.86), and stimulus-response curves (ICC=0.60-0.83). CONCLUSIONS TMS assessments of motor representation size, location, and excitability are generally reliable measures, although their reliability may vary according to the muscle under investigation. SIGNIFICANCE These results suggest that TMS measurements of motor cortex function are reliable enough to be potentially useful in investigation of motor system plasticity.

Active Finger Extension Predicts Outcomes After Constraint-Induced Movement Therapy for Individuals With Hemiparesis After Stroke

Background and Purpose— Constraint-induced movement therapy (CIMT) is a rehabilitative strategy used primarily with the post-stroke population to increase the functional use of the neurologically weaker upper extremity through massed practice while restraining the lesser involved upper extremity. Whereas research evidence supports CIMT, limited evidence exists regarding the characteristics of individuals who benefit most from this intervention. The goal of this study was to investigate the potential of 5 measures to predict functional CIMT outcomes. Methods— A convenience sample of 55 individuals, >6 months after stroke, was recruited that met specific inclusion/exclusion criteria allowing for individuals whose upper extremity was mildly to severely involved. They participated in CIMT 6 hours per day. Pretest, post-test, and follow-up assessments were performed to assess the outcomes for the Wolf Motor Function Test (WMFT). The potential predictors were minimal motor criteria (active extension of the wrist and 3 fingers), active finger extension/grasp release, grip strength, Fugl–Meyer upper extremity motor score, and the Frenchay score. A step-wise regression analysis was used in which the potential predictors were entered in a linear regression model with simultaneous entry of the dependent variables’ pretest score as the covariate. Two regressions models were determined for the dependent variable, for immediate post-test, and for follow-up post-test. Results— Finger extension was the only significant predictor of WMFT outcomes. Conclusions— When using finger extension/grasp release as a predictor in the regression equations, one can predict individual’s follow-up scores for CIMT. This experiment provides the most comprehensive investigation of predictors of CIMT outcomes to date.

Lessons Learned in Participant Recruitment and Retention: The EXCITE Trial

Participant recruitment is considered the most difficult aspect of the research process. Despite the integral role of recruitment in randomized clinical trials, publication of data defining the recruitment effort is not routine in rehabilitation initiatives. The recruitment process for the Extremity Constraint-Induced Therapy Evaluation (EXCITE) trial illustrates obstacles to and strategies for participant accrual and retention that are inherent in rehabilitation clinical trials. The purpose of this article is to increase awareness of the multiple facets of recruitment necessary for successful clinical trials, thus supporting the continued development of evidence-based practice in physical therapy. The Recruitment Index is presented as a variable to measure recruitment efficacy. In addition, ethical aspects of recruitment are explored, including informed consent and the concept of therapeutic misconception.

Repetitive transcranial magnetic stimulation as an adjunct to constraint-induced therapy: an exploratory randomized controlled trial.

Malcolm MP, Triggs WJ, Light KE, Gonzalez Rothi LJ, Wu S, Reid K, Nadeau SE: Repetitive transcranial magnetic stimulation as an adjunct to constraint-induced therapy: an exploratory randomized controlled trial. Am J Phys Med Rehabil 2007;86:707–715. Objective:To test the potential adjuvant effect of repetitive transcranial magnetic stimulation (rTMS) on motor learning in a group of stroke survivors undergoing constraint-induced therapy (CIT) for upper-limb hemiparesis. Design:This was a prospective randomized, double-blind, sham-controlled, parallel group study. Nineteen individuals, one or more years poststroke, were randomized to either a rTMS + CIT (n = 9) or a sham rTMS + CIT (n = 10) group and participated in the 2-wk intervention. Results:Regardless of group assignment, participants demonstrated significant gains on the primary outcome measures: the Wolf Motor Function Test (WMFT) and the Motor Activity Log (MAL)–Amount of Use, and on secondary outcome measures including the Box and Block Test (BBT) and the MAL–How Well. Participants receiving rTMS failed to show differential improvement on either primary outcome measure. Conclusions:Although this study provided further evidence that even relatively brief sessions of CIT can have a substantial effect, it provided no support for adjuvant use of rTMS.

The EXCITE Stroke Trial Comparing Early and Delayed Constraint-Induced Movement Therapy

Background and Purpose— Although constraint-induced movement therapy (CIMT) has been shown to improve upper extremity function in stroke survivors at both early and late stages after stroke, the comparison between participants within the same cohort but receiving the intervention at different time points has not been undertaken. Therefore, the purpose of this study was to compare functional improvements between stroke participants randomized to receive this intervention within 3 to 9 months (early group) to participants randomized on recruitment to receive the identical intervention 15 to 21 months after stroke (delayed group). Methods— Two weeks of CIMT was delivered to participants immediately after randomization (early group) or 1 year later (delayed group). Evaluators blinded to group designation administered primary (Wolf Motor Function Test, Motor Activity Log) and secondary (Stroke Impact Scale) outcome measures among the 106 early participants and 86 delayed participants before delivery of CIMT, 2 weeks thereafter, and 4, 8, and 12 months later. Results— Although both groups showed significant improvements from pretreatment to 12 months after treatment, the earlier CIMT group showed greater improvement than the delayed CIMT group in Wolf Motor Function Test Performance Time and the Motor Activity Log (P<0.0001), as well as in Stroke Impact Scale Hand and Activities domains (P<0.0009 and 0.0214, respectively). Early and delayed group comparison of scores on these measures 24 months after enrollment showed no statistically significant differences between groups. Conclusions— CIMT can be delivered to eligible patients 3 to 9 months or 15 to 21 months after stroke. Both patient groups achieved approximately the same level of significant arm motor function 24 months after enrollment. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00057018.

Practice as an intervention to improve speeded motor performance and motor learning in Parkinson’s disease

Individuals with Parkinsons disease have difficulty initiating and performing complex, sequential movements. Practice generally leads to faster initiation and execution of movements in healthy adults, however, whether practice similarly improves motor performance in patients with Parkinsons disease remains controversial. To assess the effects of practice on motor performance, patients with Parkinsons disease and control subjects practiced two, rapid arm-reaching tasks with different levels of movement complexity for 120 trials each over 2 days. Response programming was studied by analyzing the overall reaction time latency of each movement and its fractionated sub-components, premotor and motor time. Practice effects were investigated by comparing pretest performance to immediate and delayed retention test performances (10-min and 48-h rest intervals, respectively). Both patients with Parkinsons disease and control subjects improved speeded performance of sequential targeting tasks by practice and retained the improvement across both retention test intervals. Finding a learning effect for persons with Parkinsons disease supports practice as an effective rehabilitation strategy to improve motor performance of specific tasks for patients with Parkinsons disease.

Measurement structure of the Wolf Motor Function Test: implications for motor control theory.

Background. Tools chosen to measure poststroke upper-extremity rehabilitation outcomes must match contemporary theoretical expectations of motor deficit and recovery because an assessment’s theoretical underpinning forms the conceptual basis for interpreting its score. Objective. The purpose of this study was to investigate the theoretical framework of the Wolf Motor Function Test (WMFT) by (1) determining whether all items measured a single underlying trait and (2) examining the congruency between the hypothesized and the empirically determined item difficulty orders. Methods. Confirmatory factor analysis (CFA) and Rasch analysis were applied to existing WMFT Functional Ability Rating Scale data from 189 participants in the EXCITE (Extremity Constraint-Induced Therapy Evaluation) trial. Fit of a 1-factor CFA model (all items) was compared with the fit of a 2-factor CFA model (factors defined according to item object-grasp requirements) with fit indices, model comparison test, and interfactor correlations. Results. One item was missing sufficient data and therefore removed from analysis. CFA fit indices and the model-comparison test suggested that both models fit equally well. The 2-factor model yielded a strong interfactor correlation, and 13 of 14 items fit the Rasch model. The Rasch item difficulty order was consistent with the hypothesized item difficulty order. Conclusion. The results suggest that WMFT items measure a single construct. Furthermore, the results depict an item difficulty hierarchy that may advance the theoretical discussion of the person ability versus task difficulty interaction during stroke recovery.

Minimum Detectable Change of the Berg Balance Scale and Dynamic Gait Index in Older Persons at Risk for Falling

Background:The Berg Balance Scale (BBS) and the Dynamic Gait Index (DGI) are often the central components of the physical therapy evaluation to identify older adults at risk of falling. Purpose:The purpose of this study was to use the standard error of measurement to investigate the minimal detectable change associated with these clinical instruments. Methods:A sample of 42 community dwellers (older than 65 years) with a history of falls or near falls was evaluated with the BBS and DGI. Evaluations were videotaped and later rescored by 2 experienced physical therapists. Results:The mean initial BBS was 39 points (SD = 8.9, range 17–53). Rescored mean value was 40 points (SD = 8.8, range 19–55). The DGI mean initial value was 12.9 (SD = 4.5, range 3–21), and the rescored mean was 12.7 (SD = 4.6, range 4–22). MDC95% values were 6.5 BBS and 2.9 DGI points, respectively. Conclusion:These results suggest that a change of 6.5 point in the BBS and 2.9 points in the DGI is necessary to be 95% confident that genuine change in function has occurred between 2 assessments. This information is important for assessing and monitoring progress and guiding treatment for community dwellers at high risk of falling.

Strength training in spastic hemiparesis: should it be avoided?

Controversy exists between accepted principles of strength training and one of our popular neurological therapeutic exercise approaches. Graded resistive exercise is a common method of strength training in the general population. Bobath avoided resistive exercise with post-stroke individuals with spasticity suggesting that the use of effort would only increase cocontraction and reduce coordination. Bobaths theories remain unsupported. The purpose of this study was to test the clinical assumption that graded resistive exercise leads to loss of force production and force modulation in spastic subjects in such a way that spasticity and cocontraction increases and force control is reduced. Nine subjects with a diagnosis of stroke with left hemiplegia and evidence of spasticity in the left biceps performed graded resistive exercise with simultaneous measurements of cocontraction, spasticity levels, and fractionated reaction time. The results of this study indicated that there was little difference between the effects of graded exercise on the performance of paretic and non-paretic muscle. When differences were found, resistive exercise appeared to have a beneficial effect on the performance of paretic muscle. The results of this study suggest that graded resistive exercise is not detrimental to post-stroke spastic muscle, and should be considered as a possible remediation for the deficits of muscle weakness and reduced function in post-stroke individuals.