Segmental myoclonus in a child with spinal cord tumour.

Segmental spinal myoclonus (SSM) involving a child's lower limb revealed the presence of a spinal cord tumour from T8 to T12. The clinical and electrophysiological features of SSM-during the child's development were studied. The presence of this disorder at two months of age did not disturb the development of walking, but did lead to orthopaedic complications. Four electromyographic recordings performed between 23 months and 7 years 10 months of age revealed the topographical extension of the SSM, its passage to rhythmicity, variable frequency and change in the sequence of activation of the muscles. These electroclinical features enable discussion of the pathophysiology of SSM by reference to neonatal motor automatisms and spinal generators.