Hereditary congenital mirror movements

Background: Mirror movements are involuntary movements of one side of the body that accompany intentional movements of the other. They occur especially at the distal upper extremities. In a mild extend, they can regularly be seen up to the 10th year of age. Persistence into adulthood is seldom and then frequently is inherited autosomal dominant. Mirror movements can also be a symptom of Klippel-Feil syndrome, Kallmann syndrome or congenital hemiplegia.

Index patient: A 7-year-old boy was presented with mirror movements of both hands. After inconspicuous development up to the age of 2 years, the mother recognized a simultaneous movement of the passive hand while grasping with the other. Symptomatology persisted while the boy had a normal motoric and cognitive development. He had problems especially when performing complex movements, different movements with both hands, or when being distracted. Writing with the right hand, he pressed the left hand on the desk top for compensation. The examination showed no further pathologies. Electroencephalogram was normal. A further evaluation with MRI and transcranial magnetic stimulation was refused so far. Occupational therapy supporting suppression of mirror movements led to reduction of symptomatology.

Family: The mother also suffered from mirror movements and had problems especially when writing or tipping. By the time, she had learned to suppress these involuntary movements or to fix the passive hand for compensation. When performing different movements with both hands, she still has great problems. The boy has a dizygotic twin, who is asymptomatic. No further relatives are known to suffer from mirror movements.

Conclusion: Occurrence of congenital mirror movements in this family is consistent with an autosomal dominant inheritance. In principal, it is a benign movement disorder. Coping by means of fixation or suppression can be supported by occupational therapy.