Marsha Melnick

The neural consequences of repetition: Clinical implications of a learning hypothesis

Repetitive strain injuries (RSIs) are difficult to treat. Some individuals with RSIs may ultimately develop chronic pain syndromes or movement problems like focal hand dystonia (FDh), a disorder of motor control manifested in a specific context during skilled, hand tasks. This paper reports on the results of four neuroplasticity studies suggesting that repetitive hand opening and closing can lead to motor control problems, measurable somatosensory changes, and problems in graphesthesia and stereognosis. The experiments support a learning hypothesis for the origin of severe RSIs, particularly FDh. This degradation in the sensory representation of the hand may not only explain the therapeutic challenge of returning these patients to work, but also provide a foundation for developing more effective physical rehabilitation strategies. Implications and conjectures for the applications of this learning hypothesis to conditions of chronic pain are also discussed.

Development and validation of the Function In Sitting Test in adults with acute stroke.

Background and Purpose: Research studies indicate that sitting balance ability is a substantial predictor of functional recovery after stroke. There are no gold standards for sitting balance assessment, and commonly used balance measures do not isolate sitting balance abilities. This study was designed to develop, pilot test, and analyze reliability and validity of a short test of functional sitting balance in patients following acute stroke. Methods: The Function In Sitting Test (FIST) was constructed after reviewing balance measures and interviewing 15 physical therapists. A written survey regarding the FIST items and scoring scales was designed, pilot tested, and sent to 12 additional physical therapists with expertise in measurement construction, balance assessment, and/or research. Thirty-one adults who were within 3 months following stroke participated in this study. Results: The expert panel survey was returned by 83.3% of the participants. Survey feedback and weighted rank analysis reduced the number of FIST items from 26 to 17. After subject testing, Item Response Theory analysis eliminated 3 additional items. The person separation index was 0.978 and the coefficient alpha was 0.98, indicating high internal consistency of the FIST. The Item Response Theory analysis confirmed content and construct validity. Concurrent validity was supported by high correlations to the modified Rankin Scale, static balance indices, and dynamic balance grades. Discussion and Conclusions: The 14-item FIST is reliable and valid in adults following acute stroke. Studies of intra- or intertester reliability and evaluative validity studies including applications to other patient populations with sitting balance dysfunction are now necessary.

The sensory consequences of repetitive strain injury in musicians: focal dystonia of the hand1

Some individuals with repetitive strain injury (RSI) develop focal dystonia of the hand (FDh), a disorder of motor control manifested in a specific context during skilled, hand movements. This descriptive study was designed to determine if musicians with FDh had reduced tactile discrimination. Ten healthy adults and ten patients with FDh participated in the study. From the standardized Sensory Integration and Praxis Test, five subtests were selected to measure tactile discrimination. The Paired Wilcoxon Test was used to analyze, meaningful, planned pairwise differences by side and by group. The two groups performed similarly on the three tests measuring tactile motor perception (Finger Identification, Localization and Kinesthesia). However, those with FDh performed significantly worse than the healthy comparison group on two tactile perceptual tasks: (1) Graphesthesia, right affected (P < 0.003) and left unaffected (p < 0.005); and (2) Manual Form Perception (stereognosis) on the right affected (P < 0.002) and left unaffected (P < 0.002). It is possible that the somatosensory differences as measured by tactile discrimination tasks represent some degradation of the hand representation following prolonged, repetitive, near simultaneous sensory stimulation of adjacent digits. Tactile discrimination should be tested in patients with RSI to detect potential risks for developing FDh. Effective treatment of patients with RSI including FDh may need to target the somatosensory deficits in order to restore stress-free motor movements.

Comorbidity and functional mobility in persons with Parkinson disease.

OBJECTIVES To report the frequency, severity, and types of comorbidities in people with Parkinson disease (PD) using a validated self-report comorbidity screening tool, and to determine the relationship between comorbidity and functional mobility. DESIGN A secondary analysis and cross-sectional observational study design. SETTING University hospital; outpatient balance disorders laboratory. PARTICIPANTS Persons with mild to moderate idiopathic PD (N=76). INTERVENTION Not applicable. MAIN OUTCOME MEASURES The Cumulative Illness Rating Scale-Geriatric (CIRS-G) and a comprehensive mobility assessment including gait (distance walked in 3 min), balance (mini-Balance Evaluation Systems Test), and physical function (Physical Performance Test). RESULTS All participants reported comorbidities in addition to their diagnosed PD. The average ± SD number of comorbidities was 6.96 ± 2.0 (range, 2-11), and the total CIRS-G score ± SD was 12.7 ± 4.8. The most commonly reported organ systems with comorbidity were eyes and ears (89%), psychiatric (68%), musculoskeletal (64%), lower gastrointestinal (62%), respiratory (60.5%), upper gastrointestinal (59.2%), and genitourinary (53.9%). The total CIRS-G score was significantly related to functional mobility: gait (r=-.53, P=.0001), balance (r=-.43, P=.0003), and physical performance (r=-.36, P=.0041). Of the original 14 organ systems measured, there were 7 systems that, when combined, best predicted gait performance, 6 systems combined that best predicted balance performance, and 4 systems combined that predicted functional performance. CONCLUSIONS This study reports a high frequency of multiple medical system comorbidity in people with mild to moderate PD. Furthermore, comorbidity scores were associated with mobility disability: gait, balance, and physical function. Early intervention is important to delay mobility disability in PD, and we recommend that people with PD found to have comorbidities should be screened for balance and gait deficits.