[Dissociation of maturity: a typical variant of motor development (author's transl)]

71 cases are described of a typical variant of motor development, characterized by dissociation of maturity between the upper and the lower extremities. The affected children develop head and trunk control at the normal time, as well as skill in the use of their arms and hands, but they refuse to stand and walk well into their second year of life. Further characteristic features of this developmental type are: slender limbs generalized reduction of muscular tonus with well-preserved strength and lively spontaneous movements, mental irritation with temper tantrums and stereotype movements. Intellectual development is normal or moderately retarded. The following causes are discussed: constitutional and genetic factors (girls predominate), cerebral damage and treatment with hip abduction splints. The developmental type simulates cerebral palsy, chiefly spastic diplegia. There are only rare descriptions of this condition in the literature. Precise diagnosis is of practical importance, since despite similarities to spastic diplegia, the theurapeutic consequences are quite different. The prognosis of "dissociation of motor development" is good, at least with regard to the neurological symptoms. Normal standing and walking are achieved at the latest by the end of the second year of life. the prognosis of intellectual development depends on the cause and should be individually assessed.