Synergistic Model Characteristics And Intervention Strategies Of Upper Limb Flexor In Stroke Patients With Hemiplegia

Objective: To investigate the flexor-extensor muscle coordination pattern of the upper limb during posture control in healthy individuals.Method: The activities of biceps brachii muscle and triceps brachii muscle of the upper limb were recorded on 13 healthy young subjects during their postural adjustment period after the platform moves in different directions(backward-forward)and speed(normal-high).The ratio of the average integrated electromyogram(i EMG)flexor muscle to the average i EMG extensor muscle during the posture adjustment period represents the coordination pattern of flexor and extensor muscle in the upper extremity.The influence of perturbation’s direction and speed on the synergistic motor pattern was also analyzed.Results:(1)Under these four different perturbation conditions,the average i EMG of the biceps brachii muscle was not significantly different from that of the triceps muscle(P>0.05).(2)With the increase of the interference intensity,the mean average i EMG of both biceps brachii muscle and triceps brachii muscle increased significantly during posture adjustment.(3)The direction and speed of the disturbance had no significant effect on the ratio of the average i EMG flexor muscle to the average i EMG extensor muscle.Conclusion:(1)Flexor and extensor muscle of the upper limb participate in the posture adjustment together,and with the increase of the perturbation,individuals need more activities of them to help maintain balance.(2)The direction and speed of the perturbation do not affect the pattern of flexor-extensor muscle coordination.Objectives: To investigate the characteristics of the flexor synergy pattern in affected upper limb and possible interventions in stroke patients during postural control(standing and walking).Method: Wireless surface electromyography was used to record the signals of 2 sides of biceps brachii muscles,triceps brachii muscles,radial wrist flexor muslces and radial wrist extensor muscles for 20 stroke patients during standing on cushion(feet shoulder-width apart,feet together)and walking(normal speed,fast speed),aiming to analyze abnormal flexor synergies in the paretic limb.The study also conducted a correlation between spasm and flexor synergies,modified Ashworth test was used to evaluate spasticity of flexor muscles.3 specific interventions were applied to control the abnormal flexor pattern of the affected extremity while walking,their effects were respectively compared to the pre-treatment condition.Result:(1)The elbow synergy index in the affected side was significantly greater(P=0.007,P<0.001)than that of the contralateral side when standing(both feet shoulder-width apart and feet together position).There was no significant difference in muscle synergy pattern between the wrist of unaffected and affected limb(P>0.05).When it comes to walking,the elbow and wrist flexor synergy index were both significantly greater than those of the unaffected side.(2)There was no significant correlation between flexor sapsm and flexor synergy,significant correlation could only be observed in wrist flexor when standing(r=0.486,p=0.038).Patients without spasticity of flexor muscles also exhibited flexor synergy.(3)The brace(passive control)did not reduce neither elbow nor wrist synergy index of the affected limb(P=0.077,P=0.33),even causing an increase activity in biceps brachii muscle while walking.Lifting the affected limb(initiative control)could effectively reduce the wrist flexor synergy index during walking(P=0.002),but it showed no significant inhibition on the biceps brachii muscle(P=0.292).Using the healthy hand to stretch the affected upper extremity from behind during walking could effectively reduce both elbow and wrist flexor synergy index(P=0.001,P<0.0001).Conclusion:(1)Biceps brachii muscle show obvious synergy when standing,while flexor synergy spreads from proximal to distal during walking.The more difficult activity was,the greater flexor synergy was observed in the affected limb.(2)There was no significant correlation between flexor spasm and flexor synergy,patients without spasticity of flexor muscles also exhibited flexor synergy.(3)Extension brace cannot be used to control the flexor patter during movement because it could even strengthen the activities of biceps brachii muscle.Strengthen the initiative control of the affected limb by using the unaffected limb may be a feasible strategy to reduce flexor synergies.