Muscle alterations in individuals with upper motor neuron lesions

Abstract

Patients with upper motor neuron lesions (UMNL) experience movement and posture dysfunction, which hinder their mobility and performance in daily activities. Traditionally, spasticity has been considered the major determinant of movement dysfunction in these individuals. However, there is evidence that changes in muscle characteristics may contribute to movement deficits in this population. The aim of this study was to critically appraise the literature regarding characterization of passive stiffness, length-tension relationship and extensibility of muscles of individuals with UMNL. The review shows that patients with UMNL present increase in passive stiffness, shifts in the length-tension relationship, and decrease in muscle extensibility. Such alterations appear to be the result of tissue remodelling in response to specific patterns of use, with histochemical and histological alterations. Such changes in muscle tissues, in turn, may contribute to movement and posture patterns presented by these patients. The interplay between muscle properties and movement function needs to be addressed in more detail to allow the elaboration of more efficient strategies of intervention to promote functional improvement of the population with neurological deficits.