Update and review of chemonucleolysis.

To update the status of chymopapain in the treatment of herniated intervertebral discs, a review of the current literature and data from an unpublished Texas study are presented. Studies in animals and humans have consistently demonstrated that chymopapain can dissolve the nucleus pulposus. Twenty-eight uncontrolled and unblinded clinical trials involving 2845 patients showed a positive response rate of 75%. Side effects occurred in 2.4% of chymopapain-treated patients. Anaphylaxis, the most serious adverse reaction associated with chemonucleolysis, was noted in less than 1% of patients. No deaths were reported. The first double-blind, placebo-controlled study of chymopapain in the United States demonstrated no significant efficacy, but both the design and execution of the study have been criticized. Two recent double-blind, placebo-controlled studies showed success rates of 73% and 80% for chymopapain, significantly higher than for placebo treatment. Postinjection back pain and muscle spasm were the most common side effects related to chymopapain administration in one of the trials. In the uncontrolled Texas study the success rate in 408 patients treated by chymopapain was 93%. Chemonucleolysis has achieved a success rate comparable with that of surgery in the treatment of symptomatic herniated discs. Appropriate use of chymopapain can result in substantial savings in time and hospital costs.