Nucleus pulposus regeneration after chemonucleolysis with chymopapain?

Abstract

Chemonucleolysis was unsuccessful in 100 out of 519 patients with herniated lumbar discs treated within a period of 3 years. These patients were subsequently submitted to open surgery. Disc material from 88 of the 100 patients was examined by light microscopy (hematoxylin and eosin, van Gieson's, Nissl's and periodic acid-Schiff staining) to verify the effect of enzymatic activity compared to the histologic findings in a similar control group. In 84 of the 88 cases, signs of enzymatic activity were revealed by eosinophilia of the ground substance, altered Nissl staining and positive periodic acid-Schiff reaction within the chondrocyte halos. These alterations indicate that the enzyme was active and confirm the results of previous studies with smaller numbers of cases. Histologic alterations were quantified according to the intensity and extent of staining. The signs of enzymatic activity were significantly (P < 0.01) stronger after short time intervals between chemonucleolysis and surgery than after long intervals. These findings may be interpreted as indicating a regenerative potential of the nucleus pulposus.