Pediatric Movement Disorders - Spasticity

Examination

In order to examine a child with spasticity, the involved muscles must be stretched at varying speeds. For example, if the muscles of the upper leg are involved, then, during the examination, the knee is flexed and then extended at slow, intermediate, and fast speeds. Evaluating these stretches helps in determining if the resistance varies with velocity or if "catch" occurs as the velocity becomes fast enough and the spasticity has time to activate. Often there is also a "clasp-knife" release, in which there is a sudden reduction in resistance following the catch.

In children with mild or moderate spasticity, there is no increased resistance to slow movements. Therefore, if the evaluator perceives a continuous "waxy" or "lead-pipe" feeling, this is more suggestive of dystonia or parkinsonian rigidity. Since spasticity is thought to be caused by a failure in communication between the brain and spinal cord, it is also important to check for other evidence of such failure.

In particular, the involved muscles may be weak, with primitive withdrawal reflexes. These reflexes include the "triple-flexion" response of the leg, or Babinski sign (a toe moves upward when the bottom of the foot is stroked firmly with a metal object).

The mechanism in the body that produces spasticity is probably an increase in the stretch reflex; therefore, it is important to look for signs of increased stretch reflex or clonus (multiple jerks from a single tendon tap) throughout the body. The location of spasticity, weakness, and increased reflexes may be a clue to the location of the interruption of communication. In spasticity due to brain injury, including cerebral palsy, it is helpful to determine the overall distribution of weakness in order to classify the syndrome appropriately as diplegia, hemiplegia, etc. As with other childhood movement disorders, spasticity may be only one of several symptoms that are simultaneously present. It is therefore important to examine for dystonia and rigidity contributing to limb stiffness, as well as other possible disorders.