PATHOPHYSIOLOGY OF CONGENITAL MIRROR MOVEMENTS

A case of congenital mirror movements occurring in association with mi ld hemiparesis and unilateral schizencephaly was investigated using fo cal transcranial magnetic stimulation. The cortical motor representati ons for first dorsal interosseous, abductor digiti minimi and biceps b rachii were mapped for both cerebral hemispheres: bilateral short late ncy EMG responses were elicited with stimulation over the non-schizenc ephalic hemisphere while no short latency responses were obtained with stimulation over the schizencephalic hemisphere. The cortical represe ntations for all three homologous muscle pairs studied were colocalize d, and the responses occurred at identical latencies bilaterally, Our findings, plus previous observations suggesting a single functional mo tor cortex in schizencephaly, are consistent with the suggestion that mirror movements are the result of branched corticospinal projections to distal muscle groups. (C) Pearson Professional Ltd 1997