Foot dystonia and lumbar canal stenosis.

We describe a patient who developed involuntary, painless, dystonic contraction of the toes of the right foot on standing or walking. The development of this abnormal movement had been preceded by sensory disturbance on the soles of both feet, triggered by dorsiflexion of the feet. Examination showed that weight bearing on the right foot and walking brought on clawing of the toes of the right foot, which was relieved within seconds of taking pressure off the right foot. There was sensory and reflex evidence of bilateral S1 root disturbance confirmed by electrophysiology. Magnetic resonance imaging of the lumbar spine showed marked stenosis of the lumbar canal with compression of the L5 and S1 nerve roots bilaterally. The patient underwent a lumbar laminectomy with nerve root exit foramina decompression, which abolished the foot dystonia and has considerably improved the sensory disturbance. This case demonstrates that lumbar canal stenosis and/or nerve root compression, may be responsible for foot dystonia. Amelioration of the abnormal movement by surgical decompression argues strongly in favour of this hypothesis.