Central neuroplasticity and functional outcome of swinging upper limbs following repetitive locomotor training of lower limbs in stroke patients

Abstract

AimsThe aim of the study was to investigate the effect of long-term repetitive locomotor training on a treadmill with partial body weight support (TTPBWS) on motor performance of the swinging and supported paretic upper limb and to explore the neurophysiological mechanism underlying this improvement.Materials and MethodsThirty ambulatory chronic hemiparetic stroke patients were assigned randomly to either one of two experimental conditions while being trained for 20 min on a treadmill with PBWS 6 days a week for 8 weeks. Patients under condition 1 received verbal cueing to perform bilateral upper limb swinging. In condition 2, patients were instructed to support both upper limbs by holding the treadmill handrails. Fugel-Meyer upper extremity motor performance test (FMUE) and motor evoked potentials (MEPs) of the paretic middle deltoid (D), biceps brachii (BB), and abductor pollicis brevis muscles were assessed before rehabilitation (A-begin), immediately at its end (A-end), and 3 months later (A-3m). Changes in the FMUE scores and MEP variables were used for comparisons among groups.ResultsBoth rehabilitation conditions resulted in a greater than 10% increase in the mean FMUE score. Group I showed a significant improvement in MEP variables (lower resting threshold, shorter central motor conduction time, and higher amplitude) in the three tested muscles. Group II showed a significant improvement in all the MEP variables of abductor pollicis brevis muscle and an increase in the MEP amplitude of only the BB muscle. Changes in the MEP threshold and amplitude of D and BB muscles were significantly higher in the patients in group I than those in group II.ConclusionActive bilateral upper limb swinging during treadmill training is more effective in improving paretic upper limb motor performance than training with supported upper limbs on treadmill handrails. Central neural plasticity may be underlying this recovery. Task-dependent neuronal coupling between lower and upper limb muscles during walking could be beneficial in stroke rehabilitation.