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. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

BACKGROUND:Rehabilitation services after hip arthroplasty (HA) usually occur in the first 6 months following surgery. Reports in the literature suggest that 9 months to several years after HA surgery, patients are generally satisfied with pain relief. However, many express dissatisfaction with their ability to perform domestic and social activities. Reduced walking ability and long-term lower extremity (LE) muscle weakness may contribute to decreased mobility. The purpose of this study was to compare the within-group LE muscle strength, gait, and self-assessed functional mobility in adults 9 months to 6 years after HA surgery to age- and gender-matched controls.METHODS:Thirty subjects (15 HA and 15 control) were studied. LE muscle strength was assessed using the Spark handheld dynamometer. Gait parameters were measured using the GAITMAT II, and self-assessed mobility was evaluated using the hip-rating questionnaire.RESULTS:The HA group walked significantly more slowly than the control group at maximum walking speed. The operative LE of the HA group had less muscle strength than the nonoperative LE, and the hip abductors were the most affected muscle group in that LE. The HA group scored lower in the domains of impact, pain, and function on the hip-rating questionnaire.CONCLUSION:Because of long-term residual impairments and disabilities noted after HA surgery, intervention beyond the initial post-surgical rehabilitation is needed.

Malcom Randall North Florida/South Georgia Veterans Affairs Medical Center Gait and Balance Clinic and the University of Florida, Physical and Occupational Therapy Departments, Gainesville, FL.

Malcom Randall North Florida/South Georgia Veterans Affairs Medical Center Gait and Balance Clinic and the University of Florida, Physical and Occupational Therapy Departments, Gainesville, FL.

Department of Physical Therapy, University of Florida, Gainesville, Florida, VA RR&D, Geriatric Gait and Balance Disorders Clinic, Veterans Administration Hospital and GRECC, Gainesville, FL.

University of Florida Physical Therapy Department, Gait and Balance Clinic @ Malcolm Randall VAMC, Gainesville, FL.

Background and Purpose. The Timed Movement Battery (TMB) is a new assessment tool designed to measure mobility in elderly individuals. "Mobility" was defined as a person's ability to maneuver his or her body independently in order to accomplish everyday tasks. The purpose of this study was to assess the concurrent and construct validity of scores obtained with the TMB as a measure of mobility in a group of elderly individuals who reported moderate or no difficulty in performing either basic or instrumental activities of daily living (BADL or IADL). Subjects. Thirty community-dwelling elderly people, with a mean age of 77.5 years (SD=7.0, range=65-92), participated in this study. Methods. Subjects responded to 2 questionnaires regarding their activities of daily living (ADL) (ie, Barthel Index and an 18-item ADL/IADL scale) and completed 3 assessments of mobility (ie, Berg Balance Scale, Timed "Up sc Go" Test, and the TMB). Subjects were asked to perform the items on the TMB at a "self-selected" speed (their normal speed) and at a "maximum-movement" speed (as quickly as they could safely perform the items). Subjects' scores on the TMB were cross-correlated with data for 3 criterion tests (ie, Berg Balance Scale, Timed " Up & Go" Test, Barthel Index, and the 18-item ADL/IADL scale) using Spearman rank correlations and Pearson product moment correlations. Results. Composite scores of the TMB performed at self-selected speeds correlated highly with data for the criterion tests and differentiated between those subjects reporting difficulty with ADL and those reporting no difficulty. Conclusion and Discussion. These results support the validity of scores obtained with the TMB as a measure of mobility in this sample of elderly individuals with moderate or no reported difficulty with ADL.

The science of motor control provides dynamic and intriguing study for practical problems of concern to neurorehabilitation specialists. Two areas of present interest and controversy in stroke rehabilitation are addressed in this issue of NeuroRehabilitation. Section I of this jou'rnal will highlight current issues on the controversies of strengthening spastic muscle and forced-limb usage as therapeutic interventions. Section II is devoted to the topic of motor control differences following right vs. left neurologic lesions. Both of these content areas represent current scientific debate in motor control science. I hope the readers of NeuroRehabilitation find this collection of scholarly works interesting and thought provoking. To begin Section I: 'Strengthening and Forced-Limb Usage', Dr. Daniel Bourbonnais et al. present a case study demonstrating a particular type of strengthening model for motor reeducation. Based on the hypothesis that feedback on torque patterns will build strength and coordination for functional upper extremity control, Bour-

Departments of Physical Therapy, Neurology, and Neurosurgery, University of Florida, Gainesville, Fla. This work is supported in part by grants from the DSR, University of Florida.

Behrman, A L; Light, K E; Flynn, S M; Bowers, D; Triggs, W J; Friedman, W A. Author Information

University of Florida (Department of Physical Therapy, PO Box 100154, Gainesville, FL 32610-0154), Supported in part by a grant from the Foundation for Physical Therapy Inc.

Division of Physical Therapy, CB#7135, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7135