Combined biochemical and clinical investigation of chemonucleolysis failures.

To attempt to understand the etiology of failures of chemonucleolysis, biochemical analyses were performed on intervertebral disk material to determine if the enzyme had actually digested the nucleus pulposus proteoglycans. This information was then correlated with the clinical laboratory data to see if a pattern evolved for the failures. Nine chymopapain treated disks, 6 untreated herniated disks and 6 lumbar disks from scoliotic patients were obtained at surgery. The results indicated that 6 out of 9 patients treated with chymopapain had a marked reduction in the proteoglycan (hexosamine) content of their disk compared to the untreated controls. There was a significant inverse correlation of intrinsic lysosomal enzymes and hexosamine content in those cases where the chymopapain failed to destroy the proteoglycan. The other 3 patients, however, had hexosamine levels virtually identical to those disks not treated with chymopapain. The clinical evaluation, consisting of preoperative myelograms, diskograms, the surgeon's observations at laminectomy and evaluation of the postoperative regimen did not explain the failures. This study suggests that the chymopapain failures are not the result of inactivity of the enzyme or failure to digest the nuclear material in at least 6 of the 9 cases. However, there were 3 patients where either the enzyme was not reaching the nuclear material or it was inactive.