IC 25 : The End Organ : Muscle in the Cerebral Palsies

Introduction Intervention to lengthen the musculotendinous unit, or to reduce its activity, are commonly performed in children with cerebral palsy (CP) with joint passive range being used as a surrogate outcome measure of musculotendinous unit length. The development of muscle deformity in children with CP is often attributed to spasticity, which has been defined variably as a velocity-dependent resistance to stretch or a persisting increase in muscle tone. Stretch of skeletal muscle is thought to be needed to encourage muscle growth: spasticity, by impairing the ability of a muscle to be stretched, is thus considered to lead to a failure of appropriate muscle growth and the consequent development of deformity. Nonoperative intervention to lengthen muscle generally involves the use of muscle stretch, either applied for short periods or over a prolonged period, with the aim of preventing muscle deformity and facilitating muscle growth by the addition of sarcomeres to muscle fibres. Short stretches are applied through stretching programmes, while more prolonged stretches are applied through the use of serial casting or orthoses. Spasticity is addressed by denervation of muscle using botulinum toxin, with the aim of improving the capacity of a muscle to respond to passive stretch and in this way to facilitate muscle growth and function. Consensus statements have recommended the use of continuous passive stretch for children with CP from the age of six months (Gericke 2006) and the use of repeat intramuscular botulinum toxin injection from the age of two years (Heinen 2010). Nonoperative intervention, in the form or stretching modalities or botulinum toxin, is generally used with the aims of maintaining muscle growth or at least of deferring muscle growth until a single surgical intervention can be performed as the child nears skeletal maturity. Surgical intervention is generally considered to be potentially destructive to muscle and is not usually considered as an initial intervention in younger children.