Spastic co-contraction, rather that spasticity, is associated with impaired active function in adults with acquired brain injury: A pilot study

Abstract

LAY ABSTRACTSpasticity and spastic co-contraction are expressions of muscle overactivity that occur in spastic paresis syndrome after a brain injury. The objective of the present pilot study was to improve our understanding of the respective adverse consequences of spasticity and spastic co-contraction on motor disability. In contrary to spasticity, spastic co-contraction is strongly associated with motor impairment in subjects with brain injury. Therapies should be directed toward reducing spastic co-contraction in order to improve motor function. Objective: To elucidate the adverse consequences of spasticity and spastic co-contraction of elbow flexors on motor impairment and upper limb functional limitation.Design: A pilot case-controlled prospective observational study. Subjects: Ten brain-injured adults, and 10 healthy controls. Methods: The co-contraction index was computed from electromyographic recordings of elbow flexors during sub-maximal (25% Maximal Voluntary Contraction) isometric elbow extension. Spasticity was assessed with the Tardieu scale, upper limb limitation using a goniometer during active elbow extension, motor selectivity with the Fugl-Meyer Assessment for the upper limb, and motor function with the Action Research Arm Test.Results: Greater co-contraction occurred in patients with brain injury compared with controls. In contrast to spasticity, strong associations were found between the co-contraction index, the limitation of active elbow extension, the Fugl-Meyer Assessment, and the Action Research Arm Test. Conclusion: This pilot study suggests that spastic co-contraction rather than spasticity is an important factor in altered upper limb motricity in subjects with brain injury, leading to abnormal restricting arm movement patterns in subjects with more severe motor impairment. Practical applications directly concern the pre-and post-therapeutic evaluation of treatments aimed at improving motor skills in subjects with brain injury.

Upper Limbs Muscle Co-contraction Changes Correlated With the Impairment of the Corticospinal Tract in Stroke Survivors: Preliminary Evidence From Electromyography and Motor-Evoked Potential

“…Increased muscle co-contraction leads to impairment in the upper limb motor function in stroke survivors. Previous studies reported that increased muscle co-contraction had a negative effect on voluntary movement ( Chae et al, 2002 ; Chalard et al, 2019 ). It could bring about increased duration of the movement, muscle discoordination, and decreased range of movement ( Arene and Hidler, 2009 ; Gross et al, 2015 ; Sarcher et al, 2015 ).…”

Respective Contributions of Instrumented 3D Gait Analysis Data and Tibial Motor Nerve Block on Presurgical Spastic Equinus Foot Assessment: A Retrospective Study of 40 Adults

“…It is possible that this premature activation reflects a compensatory phenomenon allowing the body weight to be absorbed in foot strike ( 21 , 22 ). No relation was found between an improvement in ADF post-MNB and TS spasticity either, highlighting that spasticity assessment does not predict what happens during movement ( 4 , 38 ).…”

“…During an early swing, the TA muscle contracts concentrically, allowing the ankle to perform a rapid dorsiflexion movement, bringing the ankle to 0° for foot clearance ( 2 , 37 ). Overactivity of the calf muscles, especially the triceps surae, during this period corresponds to spastic co-contraction ( 4 ) involved in limiting active movement ( 38 ) by reversing dorsiflexor torque to plantar-flexor torque ( 39 ). This observation, described as a “stretch-sensitive paresis” ( 4 ), was noted for 26% of the cases in a hemiplegic population of 18 subjects ( 39 ).…”

Changes in intermuscular connectivity during active elbow extension reveal a functional simplification of motor control after stroke

“…root mean square value during maximal isometric voluntary elbow flexion contraction (Chalard et al, 2019). This maximal voluntary contraction was obtained from a series of three fivesecond voluntary maximal contractions, two minutes apart, performed on an isokinetic ergometer with shoulder flexion of 80 • , an internal rotation of 90 • and the bust attached.…”

“…These observations are in agreement with the general consensus on impaired muscle co-activation after stroke, which in part involves the alteration of co-contraction in this population ( Roh et al, 2013 ). Co-contraction is related to an involuntary contraction of both synergistic agonist and antagonist muscles ( Gracies, 2005 ) that occurs in healthy subjects but which is excessive in stroke subjects ( Angel, 1975 ) and can be partly responsible for the alteration of the motor function of the upper paretic limb ( Chollet et al, 1991 ; Crafton et al, 2003 ; Ohn et al, 2013 ; Chalard et al, 2019 ). It should be noted that in this study, the synergistic muscles are all muscles involved in a movement.…”