Segmental spinal dysgenesis: A report of three cases

Segmental spinal dysgenesis is an uncommon congenital spinal defect charact erized by localized segmental agenesis of the upper lumbar or thoracolumbar spine. Bony defects include significant focal canal stenosis, hypoplastic or absent vertebrae, subluxation of the spinal column, and instability. The distal bony architecture is usually normal but may be bifid. Then is signi ficant narrowing of the thecal sac and absence of adjacent nerve roots at t he level of the lesion. Distal neurologic deficits are variable in severity , the prevalence of neurogenic bladder is high, and associated anomalies ar e common. Progressive kyphosis is inevitable. The cause is unknown, but an association with maternal diabetes and with various medications and toxins has been noted. Other authors suggested a relation to an aberrant segmental vascular supply. Treatment should be directed at the establishment and mai ntenance of spinal stability and arrest of the progressive kyphosis. It sho uld consist of early anterior and posterior arthrodesis, with or without an terior decompression of the cord. Accurate visualization of this unusual de formity is difficult with conventional radiographic techniques. Three-dimen sional computerized tomographic reconstruction can therefore be invaluable in preoperative planning. We report three cases of segmental spinal dysgene sis, all of which have been uniquely detailed by striking three-dimensional imaging studies.