[Crossed plantar extension. A clinical and physiological study (author's transl)].

A 44 year-old man was examined for a slowly progressive left hemiplegia predominating on the lower limb. A left sign of Babinski was present. On the right side the plantar response was flexor. Stimulation of the right sole elicited a left extensor plantar response. CT Scan showed calcification sin the right paracentral lobule. The variations of the contralateral soleus H reflex when conditioned by a nociceptive stimulus applied on the right little toe were studied. No modification was seen. This contrasts with the facilitation observed in normal subjects and in patients with a lesion of the cerebral hemisphere not involving the paracentral lobule. It is suggested that this abnormality could contribute to the development of a crossed extensor plantar responses. Possible mechanisms of this phenomenon are briefly considered.