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Background. Neurological deficits after a stroke are commonly classified according to motor function for clinical decision making regarding discharge and rehabilitation. Participants in clinical stroke studies are also stratified by motor function to avoid a sampling bias. Objective. This post hoc analysis examined a suite of upper limb functional assessment tools to test the hypothesis that motor function of survivors of stroke can be stratified using 2 simple tests of manual dexterity despite the heterogeneity of the population. Methods. The functional ability of the more affected hand and arm was assessed for 67 hemiparetic patients, aged 18 to 83 years (mean ± standard deviation, 59.8 ± 14.0 years), at 1 to 264 months after a stroke (23.6 ± 39.6 months) using the Wolf Motor Function Test (WMFT), upper limb motor Fugl-Meyer Assessment (F-M), Box and Block Test (BBT), grooved pegboard test, and wrist range of motion. We tested the strength of our proposed stratification scheme with a hypothesis-driven hierarchical cluster analysis using standardized raw scores and dichotomous BBT and grooved pegboard test values. Results. The most salient discriminator between low and higher motor function was the ability to move >1 block on the BBT. Within the higher function group, the ability to place all 25 pegs on the grooved pegboard test discriminated between moderate and high motor function. The derived scheme was congruent with clinical observations. The WMFT timed tasks, F-M scores, and range of motion did not discriminate functional groups. Conclusions. Two simple unambiguous and objective tests of gross (BBT) and fine (grooved pegboard test) manual dexterity discriminated 3 groups of motor function ability for a heterogeneous group of patients after stroke.

Background. Functional ability is regularly monitored poststroke to assess improvement and the efficacy of clinical trials. The balance between implementation times and sensitivity has led to multidomain tools that aim to assess upper-limb function comprehensively. Objective. This study implemented 3 common multidomain tools to investigate their suitability across a broad spectrum of movement ability after stroke. Methods. Forty-nine hemiparetic patients (18 females), aged 22 to 83 years and 24.7 ± 39.2 months poststroke, were assessed before and after a 14-day upper-limb rehabilitation program of Wii-based Movement Therapy. Assessments included the upper-limb motor subscale of the Fugl-Meyer Assessment (F-M), the Wolf Motor Function Test (WMFT), and the Motor Assessment Scale (MAS) upper-limb sections 6 to 8. The MAS was analyzed both with and without the hierarchical system. Patients were stratified with low, moderate, or high motor-function. Results. Upper-limb function improved significantly for the pooled cohort for all assessments ( P < .001), although ceiling effects were evident for the F-M, floor effects for the WMFT, and both floor and ceiling effects for MAS. When analyzed by stratified subgroup these improvements were significant for all groups with the F-M, for the moderate and high motor-function groups with both the WMFT and the MAS scored without hierarchical system, but only for the high motor-function group with the hierarchically scored MAS. Conclusion. These results suggest that no single test is suitable for measuring function and improvement across the spectrum of poststroke upper-limb dysfunction and that assessment tool selection should be based on the level of residual motor-function of individual patients.

Muscle weakness is the most common outcome after stroke and a leading cause of adult-acquired motor disability. Single motor unit properties provide insight into the mechanisms of post-stroke motor impairment. Motor units on the more-affected side are reported to have lower peak firing rates, reduced discharge variability and a more compressed dynamic range than healthy subjects. The activity of 169 motor units was discriminated from surface electromyography in 28 stroke patients during sustained voluntary contractions 10% of maximal and compared to 110 units recorded in 16 healthy subjects. Motor units were recorded in three series: ankle dorsiflexion, wrist flexion and elbow flexion. Mean firing rates after stroke were significantly lower on the more-affected than the less-affected side (p < 0.001) with no differences between dominant and non-dominant sides for healthy subjects. When data were combined, firing rates on the less-affected side were significantly higher than those either on the more-affected side or healthy subjects (p < 0.001). Motor unit mean firing rate was higher in the upper-limb than the lower-limb (p < 0.05). The coefficient of variation of motor unit discharge rate was lower for motor units after stroke compared to controls for wrist flexion (p < 0.05) but not ankle dorsiflexion. However the dynamic range of motor units was compressed only for motor units on the more-affected side during wrist flexion. Our results show that the pathological change in motor unit firing rate occurs on the less-affected side after stroke and not the more-affected side as previously reported, and suggest that motor unit behavior recorded in a single muscle after stroke cannot be generalized to muscles acting on other joints even within the same limb. These data emphasize that the less-affected side does not provide a valid control for physiological studies on the more-affected side after stroke and that both sides should be compared to data from age- and sex-matched healthy subjects.

Sensation is commonly impaired immediately post-stroke but little is known about the long-term changes in cutaneous sensation that have the capacity to adversely impact independence and motor-function. We investigated cutaneous sensory thresholds across the hand in the chronic post-stroke period. Cutaneous sensation was assessed in 42 community-dwelling stroke patients and compared to 36 healthy subjects. Sensation was tested with calibrated monofilaments at 6 sites on the hand that covered the median, ulnar and radial innervation territories and included both glabrous (hairless) and hairy skin. The motor-function of stroke patients was assessed with the Wolf Motor Function Test and the upper-limb motor Fugl-Meyer Assessment. Impaired cutaneous sensation was defined as monofilament thresholds >3 SD above the mean of healthy subjects and good sensation was ≤ 3 SD. Cutaneous sensation was impaired for 33% of patients and was 40-84% worse on the more-affected side compared to healthy subjects depending on the site (p