[18p-syndrome with bilateral pyramidal tract signs, dystonia of the lower extremities and concentric visual field defect].

A case, diagnosed as 18p-syndrome by typical clinical appearance and by chromosomal analysis, presented with multiple nervous system defects consisting of bilateral pyramidal tract signs, weakness and focal dystonia of the lower extremities, and concentric visual field defect. Chromosomal analysis revealed karyotype 46, X, dic (Y;18) (p11;p11), inv(9) (p11q13), and the points of chromosomal breakages were thought to be in the short arm of chromosome 18 and in the short arm of Y chromosome. 18p-syndrome is caused by a chromosomal deletion, and presents with a wide variety of clinical appearances. Many cases have been reported since the original descriptions by de Grouchy in 1963, though with few mentions of neurological deficits other than mental retardation. Furthermore, there have been no reports of pyramidal tract signs, weakness and focal dystonia of the lower extremities, or visual field defect, without recognizable anatomical abnormalities. Our case of 18p-syndrome is quite rare because of multiple nervous system abnormalities mentioned above, not accompanied by malformations of the central nervous system.