Sacral agenesis with progressive neurological deficit.

In the past, sacral agenesis was thought to be a form of bony malformation associated with static neurological deficits. The majority of therapeutic recommendations involved orthopedic correction of foot and leg deformities. Myelographic studies were seldom obtained, and surgical exploration was rarely attempted. We recently encountered two cases of sacral agenesis with progressive neurological deficits; both patients had myelographically demonstrable lesions and both responded favorably to surgical treatment. We believe that patients with caudal agenesis can be divided into two groups: one with static neurological deficits that probably would not improve after operation, and the other with progressive neurological findings probably associated with specific neuropathological lesions that would be amenable to operative therapy. We therefore endorse a more aggressive approach toward the management of patients in the second group. Upon the diagnosis of caudal agenesis, a detailed documentation of the base line neurological status, the bladder and bowel functions, and the degree of lower limb deformities should be obtained. A diligent follow-up program is essential to detect progression which, when present, should be followed promptly by myelography and surgical intervention. The etiology, classifications, and clinical features of sacral agenesis are discussed, and the associated neuropathological abnormalities are analyzed.