Abnormal projection of corticospinal tracts in a patient with congenital mirror movements.

A 31 year-old woman with familial congenital mirror movements not associated with other neurological defects underwent a detailed neurophysiological evaluation including: voluntary electromyographic activity recorded from upper limbs in response to acoustic stimuli, motor evoked potentials from the thenar muscles to focal transcranial magnetic stimulation, F waves from upper extremities, scalp somatosensory evoked potentials and long-latency responses from thenar muscles to electric stimulation of the median nerve. The results were consistent with the presence of fast-conducting pathways connecting each hand motor cortex with both contra- and ipsilateral spinal motoneurones.