PHENOTYPES OF HEMIPARESIS DUE TO VARYING SEVERITY OF THE IMPAIRMENT OF THE CORTICOSPINAL INNERVATION

Abstract

The impairment of motor functions after stroke has a polymorphic structure, in which a decrease in strength, impairment of selective control of movements, and the development of a spastic syndrome are most studied. With partial lesions of the primary motor cortex and impairment of corticospinal innervation, the recovery of motor control is supported by various processes of neuroplastic reorganization. Among humans, the influence of corticospinal innervation impairments on the functional state of motor control and the development of spasticity syndrome remains poorly understood. The aim of our work was to establish the phenotypes of the functional state of motor control with different severity of corticospinal innervation impairment among patients after an ischemic stroke. We found that when the corticospinal innervation is impaired on 32.9% [31.9-28.8] the control of the distal parts of the extremities and the synergies of the proximal parts are fractionated, and when on 92.9% [96-80.5] the control of the distal parts is lost and the number of synergies of proximal parts are decreases. With complete impairment of the corticospinal innervation, remains control of primitive synergies of only the proximal parts of the extremities. The development of spastic syndrome was higher in groups with increased segmental excitability, which was not directly related to the state of corticospinal innervation impairment. Thus, the phenotype of hemiparesis with an increase of the corticospinal innervation impairment is characterized by the dominance of a decrease of the strength of the distal parts of the extremities and an impairment of proximo-distal inter-joints coordination. Restoration of strength and control of the proximal parts of the extremities, axial muscles of the trunk and regulation of the muscles tone indicate the involvement of the alternative from the corticospinal, descending cortical and subcortical motor pathways.