Neuropathologic aspects of arthrogryposis multiplex congenita.

Arthrogryposis multiplex congenita is not a specific disorder but rather a symptom complex of congenital joint contractures associated with both neurogenic and myopathic disorders. Pathologic studies, including autopsy evaluation and muscle biopsy alone, were performed on 74 children with features of arthrogryposis. In 69 children (93%), the deformities were found to be neurogenic in origin, while five (7%) had myopathic disorders. The children in these two groups could be subdivided into 17 specific disorders, depending on the site of the pathologic lesions: anterior horn cells, roots, peripheral nerves, motor end-plates, or muscle. Disorders associated with dysgenesis of anterior horn cells were the most common pathologic type. The neurogenic groups were also characterized by a high incidence of other congenital anomalies, while the myopathic group had few associated defects. The main feature shared by these disorders appears to be the presence of severe weakness early in fetal development, which immobilizes joints, resulting in contractures.