Chemonucleolysis is the term used to denote chemical destruction of nucleus pulposus [Cehmo+nucleo+lysis]. This involves the intradiscal injection of chymopapain which causes hydrolysis of the cementing protein of the nucleus pulposus. This causes a decrease in water binding capacity leading to a reduction in size and drying the disc.
Chemonucleolysis is one of the methods to treat disc herniation not responding to conservative therapy.
Basis of Chemonucleolysis
Nucleus Pulposus is soft, gelatinous material in the center of the disc and is surrounded by a tough fibrous coating annulus fibrosus. In disc herniation weakened or torn annulus fibrosus allows nucleus pulposus to ooze out
Chemonucleolysis uses chymopapain, an enzyme derived from papyrus, to dissolve the disk material. Chemonucleolysis is appropriate for only some cases of HNP.
Chemonucleolysis is not effective in sequestered discs. In a sequestered disk, a fragment of the nucleus pulposus breaks loose from the disk and is free in the spinal canal.
Indications and Patient Profile
A patient is a good candidate for chemonucleolysis if
- 18-50 years of age
- Leg pain is worse than lower back pain
- Failure of conservative treatment
- There is a documentable compression of neural structures by the herniated disc
- Patient prefers than to surgical removal to avoid surgery
There are some situations in which chemonucleolysis should not be performed.
- Allergy to chymopapain
- Pregnant patients
- Sequestered disc
- Presence of neurological disease such as multiple sclerosis
How Chemonucleolysis is Done?
Before the procedure a confirmation of disc as a cause of pain is necessary. This most unequivocally is done by discography but some settle for CT Myelogram
The patient might be admitted a day prior to the procedure or the procedure can be done on an outpatient basis.
The patient might be put under general or local anesthesia may be used. An intravenous access should be present before the procedure is carried out.
The patient is taken in the left lateral decubitus position and the disc is reached using a needle. Discogram may be done to confirm the place of the needle. The enzyme is injected and the needle is withdrawn.
Recovery can take 6-12 weeks. This means that there is no need to worry if it will take some weeks for the relief of pain. It is advisable to prescribe NSAID treatment on a routine basis for the first 1-2 weeks. A support corset can be of benefit.
Following the treatment patients may feel lower back stiffness, which goes away in a few weeks. Heavy lifting and sports activities should be avoided for three months.
Risks and Complications
The greatest risk is that the patient may be allergic to chymopapain. Increased back pain and muscle spasms after the injection may occur. Severe back pain that may limit daily activities for up to 3 months after treatment for many people.
There is an increase in serum levels of keratan sulfate and urinary glycosaminoglycans during the first 5 days after injection due to degradation of disc proteoglycans is dose-dependent.
Too high a dose produces significant annular destruction. Re-expansion of a narrowed disc after chymopapain injection, as has been noted in healthy discs in young animals, is not seen consistently, but does occur in clinical practice.
Most of the adverse events in most instances appear to be the consequence of poor needle placement.
Infections can occur in rare cases.
Hemorrhages within the central nervous system are caused by intrathecal [inside the spinal canal] injection of the enzyme.
Many patients feel immediate relief from pain, but, in about 30% of patients, maximal relief takes six weeks. The long-term (seven to 20 years) success rate averages about 75%, which is comparable to the success rate for conventional surgery.
Discectomy (or microdiscectomy) is more effective than chemonucleolysis and has fewer potential side effects
Chemonucleolysis is an attempt to eliminate pain sooner than nature does. The ideal patient for chemonucleolysis is also the patient for surgical discectomy. Success can be expected if there is a sciatic pain, and there is demonstrable compression.
Current Place In Medical Practice
The chemonucleolysis is subject of controversy and is a matter of debate when the comparison is made with surgery. There are people in favor of and against the treatment vis a vis surgery.
The treatment is more popular in Europe than America.