Writer’s Cramp with Mirror Movements
Motor overflow refers to unintentional muscle contractions which accompany but are anatomically separate from primary involuntary dystonic movements. In the case of writer’s cramp, mirror movements are a form of overflow in which abnormal movements occur in the unoccupied affected hand while writing with the opposite unaffected hand. This phenomenon suggests the presence of more widespread abnormalities of motor control in patients with focal dystonia, possibly due to a loss of normal inhibitory mechanisms. When looked for in individuals with writer’s cramp, the appearance of mirror dystonia in the affected resting hand is common when writing with the opposite unaffected hand.
KeywordsPublic Health Internal Medicine Motor Control Botulinum Toxin Inhibitory Mechanism
Writer's Cramp w. mirror movements.mp4 (MP4 17,400KB)
Clip 1: the patient attempts to write with her dominant right hand. She exhibits severe flexion dystonia of the right wrist and fingers with ipsilateral overflow to the elbow and shoulder regions. Writing is intermittently interrupted due to severe cramps in her right hand. Clip 2: the patient begins to write with her unaffected left hand and within seconds develops mirror dystonia in the right hand manifested by flexion of the right wrist and fingers.