Role of a wireless surface electromyography in dystonic gait in functional movement disorders: A case report

BACKGROUND: Dystonic gait (DG) is one of clinical symptoms associated with functional dystonia in the functional movement disorders (FMDs). Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation. There is no report for DG in FMDs caused by an abnormal pattern in the ankle muscle recruitment strategy during gait. CASE SUMMARY: A 52-year-old male patient presented with persistent limping gait. When we requested him to do dorsiflexion and plantar flexion of his ankle in the standing and seating positions, we didn’t see any abnormality. However, we could see the DG during the gait. There were no evidences of common peroneal neuropathy and L5 radiculopathy in the electrodiagnostic study. Magnetic resonance imaging of the lumbar spine, lower leg, and brain had no definite finding. No specific finding was seen in the neurologic examination. For further evaluation, a wireless surface electromyography (EMG) was performed. During the gait, EMG amplitude of left medial and lateral gastrocnemius (GCM) muscles was larger than right medial and lateral GCM muscles. When we analyzed EMG signals for each muscle, there were EMG bursts of double-contraction in the left medial and lateral GCM muscles, while EMG analysis of right medial and lateral GCM muscles noted regular bursts of single contraction. We could find a cause of DG in FMDs. CONCLUSION: We report an importance of a wireless surface EMG, in which other examination didn’t reveal the cause of DG in FMDs.