Clinical Evaluation of Hypertonia in the Triceps Surae Muscles

Abstract

Hypertonia of the triceps surae muscles is a common consequence of acquired brain injury. The increased resistance to passive lengthening results from rheologic changes within the musculotendinous unit, in addition to altered descending facilitatory influences on the alpha motor-neurone pool. Hypertonia can contribute to abnormal ankle joint biomechanics during the performance of functional tasks. In order to achieve effective outcomes, therapeutic interventions need to be based on accurate measurement and analysis of the various components of hypertonia. Some options for the clinical evaluation of hypertonia at the ankle joint are discussed in this paper. Reflex hyper-excitability and rheologic changes within the musculotendinous unit are inextricably linked. Serial evaluation of passive range of motion and muscle stiffness in patients with hypertonia provides useful information for treatment planning. In addition to measurement of the available passive range of motion when maximal force is applied, there is a need to consider methods of monitoring changes in muscle stiffness following brain injury.