Myelopathy in infancy complicating congenital atlantoaxial dislocation.

Two infants had congenital atlantoaxial dislocation associated with myelopathy. One of them, a 3-month-old girl, showed anterior dislocation of the atlas on the axis, and had extreme weakness of the extremities. Another patient, an 8-month-old boy, showed tetraplegia, and posterior dislocation with absent odontoid process was demonstrated radiologically. These cases add another cause to the varied etiologies of floppiness in early infancy.