European consensus on the concepts and measurement of the pathophysiological neuromuscular responses to passive muscle stretch.

BACKGROUND AND PURPOSE: To support clinical decision-making in central neurological disorders, a physical examination is used to assess responses to passive muscle stretch. However, what exactly is being assessed is expressed and interpreted in different ways. A clear diagnostic framework is lacking. Therefore, the aim was to arrive at unambiguous terminology about the concepts and measurement around pathophysiological neuromuscular response to passive muscle stretch. METHODS: During two consensus meetings, 37 experts from 12 European countries filled online questionnaires based on a Delphi approach, followed by plenary discussion after rounds. Consensus was reached for agreement ≥75%. RESULTS: The term hyper-resistance should be used to describe the phenomenon of impaired neuromuscular response during passive stretch, instead of for example 'spasticity' or 'hypertonia'. From there, it is essential to distinguish non-neural (tissue-related) from neural (central nervous system related) contributions to hyper-resistance. Tissue contributions are elasticity, viscosity and muscle shortening. Neural contributions are velocity dependent stretch hyperreflexia and non-velocity dependent involuntary background activation. The term 'spasticity' should only be used next to stretch hyperreflexia, and 'stiffness' next to passive tissue contributions. When joint angle, moment and electromyography are recorded, components of hyper-resistance within the framework can be quantitatively assessed. CONCLUSIONS: A conceptual framework of pathophysiological responses to passive muscle stretch is defined. This framework can be used in clinical assessment of hyper-resistance and will improve communication between clinicians. Components within the framework are defined by objective parameters from instrumented assessment. These parameters need experimental validation in order to develop treatment algorithms based on the aetiology of the clinical phenomena.

Botulinum toxin treatment of spasticity in diplegic cerebral palsy: a randomized, double-blind, placebo-controlled, dose-ranging study.

This study evaluated the efficacy and safety of three doses of botulinum toxin A (BTX-A; Dysport) in 125 patients (mean age 5.2 years, SD 2; 54% male)with dynamic equinus spasticity during walking. Participants were randomized to receive Dysport (10, 20, or 30 units/kg) or placebo to the gastrocnemius muscle of both legs. Muscle length was calculated from electrogoniometric measurements and the change in the dynamic component of gastrocnemius shortening at four weeks was prospectively identified as the primary outcome measure. All treatment groups showed statistically significant decreases in dynamic component compared with placebo at 4 weeks. Mean improvement in dynamic component was most pronounced in the 20 units/kg group, being equivalent to an increase in dorsiflexion with the knee extended at 19 degrees, and was still present at 16 weeks. The safety profile of the toxin appears satisfactory.