Structural and pathophysiological muscle changes up to one year after post-stroke hemiplegia: a systematic review

Abstract

INTRODUCTION: Muscle changes after stroke cannot be explained solely on the basis of corticospinal bundle damage. Muscle-specific chang- es contribute to limited functional recovery but have been poorly characterized. EVIDENCE ACQUISITION: We conducted a systematic review of muscular changes occurring at the histological, neuromuscular and func- tional levels during the first year after the onset of post-stroke hemiplegia. A literature search was performed on PubMed, Embase and CINHAL databases up to November 2022 using a keyword combination comprising cerebral stroke, hemiplegic, atrophy, muscle structure, paresis, skel- etal muscle fiber type, motor unit, oxidative stress, strength, motor control. EVIDENCE SYNTHESIS: Twenty-seven trial reports were included in the review, out of 12,798 articles screened. Structural modifications de- scribed on the paretic side include atrophy, transformation of type II fibers into type I fibers, decrease in fiber diameter and apparent myofilament disorganization from the first week post-stroke up to the fourth month. Reported biochemical changes comprise the abnormal presence of lipid droplets and glycogen granules in the subsarcolemmal region during the first month post-stroke. At the neurophysiological level, studies indicate an early decrease in the number and activity of motor units, correlated with the degree of motor impairment. All these modifications were present to a lesser degree on the non-paretic side. Although only sparse data concerning the subacute stage are available, these changes seem to appear during the first two weeks post-stroke and continue up to the third or fourth month. CONCLUSIONS: Considering these early pathophysiological changes on both the paretic and non-paretic sides, it seems crucial to promptly stimulate central and also peripheral muscular activation after stro