[Vitamin B1 deficiency polyneuropathy presenting homolateral imitative synkinesia].

We report a 56-year-old woman with vitamin B1 polyneuropathy, showing bilateral homolateral imitative synkinesia. Needle electromyogram revealed neurogenic changes, and the amplitude of muscle action potential was low. Sural nerve biopsy showed a marked loss of myelinated fibers, and severe axonal degeneration was diagnosed. Spinal and brain MRI revealed no abnormalities. In the literature, these synkinesias were observed in patients with parietal, thalamic, and basal ganglia lesions and with chorea. We suggest that this synkinesia is the release phenomenon in the circuit of the motor programming system due to the disturbance of peripheral nerve or funiculus posterior.