[Adult-onset primary focal foot dystonia]

Adult-onset primary focal foot dystonia is a rare event. Up to now, only 7 cases have been reported in the literature. Since the idiopathic-type food dystonia is uncommon in adults, secondary types must be ruled out.

We present the case of a 51 year woman with a 3 year history of focal food dystonia. She had abnormal posture of the foot with plantar flexion and inversion, which worsened with action. Complementary studies aimed at ruling out secondary causes were all negative. The dystonia remained limited to her food and she did not develop any other neurological symptoms. She benefited from botulinum toxin treatment.

Primary focal foot dystonia is uncommon in adults. The most common pattern is plantar and five toes flexion. Associated pain is common. Its pathogenesis is only partially understood, the neurophysiologic studies and functional resonance showing a loss of inhibitory control at spine and brainstem levels, abnormal cortical plasticity and altered sensorimotor integration. The response of this disorder to drugs is poor, however, the patients may benefit from botulinum toxin infiltrations of the muscles involved.