RESUMO
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.
RESUMO
BACKGROUND: Virtual-reality is increasingly used to improve rehabilitation outcomes. The Nintendo Wii offers an in-expensive alternative to more complex systems. OBJECTIVE: To investigate the efficacy of Wii-based therapy for post-stroke rehabilitation. METHODS: Seven patients (5 men, 2 women, aged 42-83 years; 1-38 months post-stroke, mean 15.3 months) and 5 healthy controls (3 men, 2 women, aged 41-71 years) undertook 1 h of therapy on 10 consecutive weekdays. Patients progressively increased home practice to 3 h per day. RESULTS: Functional ability improved for every patient. The mean performance time significantly decreased per Wolf Motor Function Test task, from 3.2 to 2.8 s, and Fugl-Meyer Assessment scores increased from 42.3 to 47.3. Upper extremity range-of-motion increased by 20.1º and 14.33º for passive and active movements, respectively. Mean Motor Activity Log (Quality of Movement scale) scores increased from 63.2 to 87.5, reflecting a transfer of functional recovery to everyday activities. Balance and dexterity did not improve significantly. No significant change was seen in any of these measures for healthy controls, despite improved skill levels for Wii games. CONCLUSION: An intensive 2-week protocol resulted in significant and clinically relevant improvements in functional motor ability post-stroke. These gains translated to improvement in activities of daily living.