Experimental studies on the effect of chymopapain on nerve root compression caused by intervertebral disk material.

Chymopapain degrades the nucleus pulposus portion of the intervertebral disk of rabbits. The degradation is not grossly visible until 15 days post-injection. Depolymerization of the chondromucoprotein and decreases in the ability of a disk to imbibe fluid, is, in effect, a "chemical decompression" of the nucleur pulposus. The enzyme must come into direct contact with the chondromucoprotein complex of the disk material, and to a significant extent also must reach the area of disk material adjacent to the herniated annulus. Rapid depolymerization of the chondromucoprotein complex on a biomechanical level, and "decompression" of disk material on a biomechanical level can be correlated with relief of pain in all types of disk herniation in human beings. A primary biochemical change in the disk material would lead to a secondary decrease in inflammation if the change led to a "decompression" of the chondromucoprotein. Since the primary effect of chymopapain is on the chondromucoprotein of the disk, beneficial results would not be expected if nerve root compression is due to bony impingement or scar tissue following previous surgery. Chymopapain did not seem to possess any anti-inflammatory properties when bone was used as an irritant under a nerve root. However, this was technically difficult to evaluate and the possibility that chymopapain may also interfere with a chemical mediator of pain or interfere directly with an inflammatory reaction secondary to root compression can not be excluded.