Lumbar disk degeneration in spinal dysraphism.

Eight of the 22 patients had spina bifida aperta, and 14 had spina bifida occulta. These included eight cases with repaired myelomeningocele, seven with an intraspinal lipoma and tethering of cord , three with dermal sinuses, and one with diastematomyelia. Bulging and low signal intensity of the nucleus pulposus on T2-weighted images are the criteria for disk degeneration [1 , 2] . In our study, 12 patients (54 .5%), eight with spina bifida occulta and four with spina bifida aperta, had signs of disk degeneration in 17 disks. Twelve of these disks were present in the patients with spina bifida occulta, and five were present in those with spina bifida aperta. In nine disks, the most remarkable sign was the low signal on T2-weighted images. In seven of the 17 disks, however, bulging was the most striking phenomenon. The distribution of the 17 degenerated disks was as follows: three at the L3-L4 level , seven at the L4-L5 level, and seven at the L5-S1 level (Figs. 1 and 2).