Factors Underlying Abnormal Posture and Movement in Spastic Hemiparesis

Abstract

Hemiparetic stroke is accompanied by abnormalities of muscle tone (identified as spastic hypertonia), weakness for voluntary movement, and disturbances of muscular coordination. The first two disturbances, i.e., spasticity and weakness, are the most visible and the most intensively studied, yet the disturbance of muscular coordination is often the most incapacitating, and the least well understood. For example, it is widely known that in many subjects disturbances of voluntary movement may be masked by abnormalities of muscle tone and/or concurrent muscular weakness. Yet when these physical signs are treated effectively, or when they resolve spontaneously, the resulting incoordination and motor impairment is still severe. It is therefore likely that in many hemiparetic stroke subjects, neither increases in muscle tone nor muscular weakness are the primary sources of movement dysfunction or of their global disability.