Hemiplegic atrophy

Abstract

Anterior tibial muscle biopsies of the hemiplegic side of 16 patients with a cerebrovascular accident in the middle cerebral artery region were analyzed qualitatively and quantitatively by enzyme histochemistry and electron microscopy. Patients grouped according to the time lapsed as from the occurrence of the accident (1-17 months) demonstrated a progressive decrease in the fiber diameter and changes in fiber type distribution with predominant type II atrophy and type I predominance. Nuclear internalization, myopathic alterations, and perifascicular fatty infiltrations were observed constantly. In the affected fibers the ultrastructural findings were myofibrillar alterations with the formation of rods and cytoplasmic bodies. There was accumulation of lipofuscin, glycogen, and lipid droplets. Microvascular changes were observed frequently. Biopsies from the asymptomatic legs were either normal or showed age-related muscle alterations. Correlation was noted between the clinical and functional status of the patients and the morphological aspects seen in muscle biopsies.

Single motor unit firing rate after stroke is higher on the less-affected side during stable low-level voluntary contractions

“…The changes in motor unit behavior in both the upper and lower limbs may result from altered physiology such as decreased central drive (e.g., Nielsen et al, 2008; Klein et al, 2013) but also from altered anatomy. Within muscles there may be a reduction in the number of functioning motor units (Hara et al, 2000, 2004; Arasaki et al, 2006; Lukács et al, 2008); and muscle fiber atrophy (Scelsi et al, 1984; Slager et al, 1985) associated with muscle disuse (Ramsay et al, 2011). Perhaps the least understood change in muscles after stroke, and one that will affect the behavior of individual motor units, is the pattern of denervation and reinnervation that is thought to underpin changes in muscle phenotype (for review see Hafer-Macko et al, 2008).…”

Poststroke Muscle Architectural Parameters of the Tibialis Anterior and the Potential Implications for Rehabilitation of Foot Drop

“…Achilles tendon properties have been shown to change between the paretic and nonparetic sides [20], and it is still unclear whether the properties of the tibialis anterior tendon change following stroke. Finally, we did not look at changes in muscle fiber type although [30] performed histological biopsies of the tibialis anterior and found that type II muscle fibers reduce in number and diameter, with a predominant shift towards type I fibers. This change in fiber type ratio, if consistent for chronic stroke survivors, may be indicative of activation failure or disuse.…”

Age- and Stroke-Related Skeletal Muscle Changes

“…After a stroke the number of Type II fibers progressively decrease, resulting in a loss of skeletal muscle cross-sectional area. 11, 31, 32 Similar to age-related muscle atrophy, after stroke there is a progressive decrease in muscle fiber size bilaterally, with greater decreases on the more involved side. 32 Stroke-induced muscle fiber reductions lead to a decrease in muscle cross-sectional area.…”

“…11, 31, 32 Similar to age-related muscle atrophy, after stroke there is a progressive decrease in muscle fiber size bilaterally, with greater decreases on the more involved side. 32 Stroke-induced muscle fiber reductions lead to a decrease in muscle cross-sectional area. In individuals post-stroke, diminished force production and contraction speed secondary to muscle atrophy may be observed as difficulty with sit to stand transfers, 33, 34 limitations in stair negotiation, 35 and impaired balance on compliant surfaces.…”