The mechanism of sciatic pain relief by chemonucleolysis.

Chemonucleolysis must relieve sciatic pain by some means other than the removal of the disc protrusion from the neural canal, because the protrusion characteristically persists despite the resolution of sciatic pain. This paper analyzes the mechanism of symptom production in sciatica and identifies how chemonucleolysis relieves these symptoms.Pressure can be exerted on a nerve root by a disc protrusion without compression against the posterior wall of the neural canal. This pressure is the result of tension produced in the nerve root when it is deformed by the disc protrusion. A previously unrecognized principle of nerve root-disc protrusion mechanics is identified. For a given disc protrusion, narrowing the disc reduces the tension in the nerve root and therefore the pressure on the nerve root; conversely, widening the disc increases the tension and pressure on the nerve root. Disc narrowing is in itself a mechanism by which chemonucleolysis relieves sciatic pain.