Tonic foot: clinical and neurophysiological study of a case

A case of involuntary plantar flexion of the toes and sole with no other neurological pathological sign is reported. The electromyographic activity of some muscles of the involved limb. the behavior of the phenomenon during the sleep-wakefulness cycle and spinal reflex excitability have been studied. According to the clinical and neurophysiological findings, the phenomenon appears to be a dystonia. Such a dystonia may occur as the only pathological neurological sign or together with the other signs of central nervous system involvement. Particular care has to be taken to distinguish 'tonic foot' from hypertonus of sole flexor muscles occurring almost always in all spastic hemipareses.