Spondylolisthesis with sciatica. Magnetic resonance findings and chemonucleolysis.

Fifteen patients with bilateral lumbar isthmic spondylolisthesis and unilateral sciatica were examined with magnetic resonance imaging. All patients had a disc protrusion at the level of the spondylolisthesis. Nine patients had a central herniated disc that caused dural sac deformation; in 6 of these patients there was extension to the disc tissue into the foramen. In 5 patients there was no clear dural sac deformation, but there was a foraminal disc protrusion that caused nerve root compression. In 1 patient there was a hernia lateral to the foramen. In none of the patients was there evidence of compression by bony elements. No abnormalities on adjacent levels were found. All 15 patients were treated with chemonucleolysis. There were no complications. A followup study was done after 19 months (range, 10-42 months). The result was rated as good or excellent in 10 of 12 patients with a spondylolisthesis of L5 and in 1 of 3 patients with a spondylolisthesis of L4. Magnetic resonance imaging showed a decrease in dural sac deformation in 4 patients, no clear decrease in 3, and a slight increase in 2. There were no distinct foraminal changes in 9 of 11 patients.