Magnetic stimulation study in mirror movements.

A young man with congenital mirror movements was studied by non-invasive magnetic stimulation. Radiological examination showed no craniocervical or pituitary abnormality except for mild atrophy of the right hippocampus. Magnetic stimulation of the motor cortex caused large amplitudes in the ipsilateral hand muscles, indicating the possibility of functional disorder in the motor pathways from the motor cortex to muscles in the upper extremities.