Hereditary mirror movements--a case report.

A five-year-old girl with abnormal mirror movements is described. The phenomenon is observed in the distal parts of the extremities and is most marked in the hands. An extensive neuropediatric examination including computerized tomography of the brain has not revealed any further abnormalities, nor has it been possible to identify the pathogenetic mechanism. The clinical picture corresponds to that previously reported in cases of hereditary mirror movements--a condition with unknown pathogenesis affecting individuals that in other respects are neurologically normal. The disorder is considered to be dominantly inherited but in this case available data suggest a recessive mode of inheritance. There is no doubt that the girl of this report is getting increasingly embarrassed by her condition. Obviously mirror movements of this degree constitute a slight to moderate handicap.