1. atonic pseudoparalysis of congenital origin (neither familial nor hereditary), observed especially in infants and characterized by absences of muscular tone only in muscles innervated by the spinal nerves. Syn: congenital atonic pseudoparalysis, myatonia congenita, Oppenheim’s disease, Oppenheim’s syndrome.
2. an indefinite term for a number of congenital neuromuscular disorders that cause generalized myotonia in young children, and that have a benign course (static or regressive).