Neuropathologic findings in the spinal cords of 10 infants with arthrogryposis.

The lumbosacral cord segments of 10 infants with varying clinical forms of neurogenic arthrogryposis were compared with similar spinal cord segments from an infant with congenital contractures secondary to uterine constraint, 8 infants with Werdnig-Hoffman syndrome, and 11 age-matched controls. Neuronal numbers, sizes, and distribution were measured within the anterior horns. In addition to the classical reduction in the numbers of alpha motor neurons in both pathologic states, this study found the smaller neurons of the anterior horn were absent or diminished in Werdnig-Hoffman syndrome, while those cells were present in increased numbers with abnormal histology in all the patients with arthrogryposis. In 5 of the patients with arthrogryposis, the pathologic pattern was consistent throughout each cord segment; in 5 others, normal alpha neurons were retained and unequally distributed in the anterior horn segments. This unequal distribution predicted the muscle group involvement and suggested the mechanism for intrauterine joint fixation in these patients. The pathologic changes in the patients with arthrogryposis appear to be unique in spite of the heterogeneity of etiology and the clinical presentation.