Imitation synkinesia and sensory control of movement.

Immitation synkinesia is usually associated with thalamic or parietal lesions. Analysis of three cases shows that the lesions may affect the posterior columns of the spinal cord or even the peripheral nervous system. In our cases, two facts stand out, a large measure of integrity of motor activity and predominant disturbances of lemniscal sensation. Imitation synkinesia should therefore not be seen as due to a lesion of a particular structure but to the disorganization of the lemniscal system at any level. Functional interconnection between the lemniscal and motor systems occurs only in the cerebral cortex. In the light of this fact, imitation synkinesia can be interpreted as the loss of particular functions in the principal cortical motor neurons.