Principles and Uses of Radiofrequency Nerve Lesioning in Chronic Pain Control

In the management of chronic pain, the value of permanent nerve blocks has long been recognized. Number of recent studies confirmed that nerves release substances in the joints, ligaments, and muscle tendons and thus contribute to the chronic inflammation. To this end, several surgical and nonsurgical methods have been devised. Surgical techniques are usually more involved and serve as a last resort. Surgical transection of peripheral nerves may cause neuroma formation and deafferentation pain. Such considerations lead to a search for nonsurgical nerve destruction techniques.

Several methods of nerve destruction are generally accepted:

1. Injection of neurolytic substances, such as absolute alcohol, phenol or glycerin, are done under X-ray with electrical nerve locator and are use for the nerve destruction and muscle denervation.

2. Radiofrequency (RF) lesioning is a more refined technique based on the thermocoagulation of selected nerves using an electrode capable of accurate temperature generation. Radiofrequency is a special type of electricity. The electricity that you use at home alternates with a frequency of 50/sec. In radiofrequency that frequency is much higher, it is 500.000/sec. Radiofrequency has been used in the treatment of pain for over 30 years. A special type of needle was positioned near to the nerve causing the pain. This had to be done very accurately using X-ray control to make sure that the effect would be optimal. Radiofrequency current was then sent through the needle and this caused heating of the needle tip. This caused some damage to the nerve, just enough to relieve the pain.

The advantages of radiofrequency lesioning

* Lesion size can be accurately controlled, allowing lesioning of small nerves without damaging nearby motor and other sensory nerves. * Recovery is rapid and usually uneventful, allowing the patient to return to work or normal daily activity more quickly.

* The nerve lesion is usually long-lasting. An accurately done lesion may give pain relief for years.

* Nerve lesion heals without neuroma formation. * The rate of side effects and complications is low.

* When pain recurs, nerve lesion can be repeated as necessary. Contraindications and limitations

* Pain control with nerve lesioning is a palliative measure and, therefore, should not be considered in place of corrective surgical treatment.

* Before the procedure, the patient must have realistic expectations and must understand that the aim is to reduce the pain, not stop it completely.

* Before neurodestructive procedures, diagnostic blocks should give good pain relief. The same diagnostic block should be repeated at least once more, even if the pain relief from the first block was excellent, to decrease the chance of placebo effect. If the result is not clear, differential blocks should be used.

* Patients with pain complaints at multiple locations or with wide distribution of pain usually respond poorly to RF procedures.

* The patient must realize that single target lesioning may not be sufficient, necessitating complementary blocks for better pain relief. Indications Facet joint pain: Pain originating from facet joints is a common component of low back and neck pain (20 - 40% of patients with back pain). This mechanical aspect of back pain is usually not amenable to surgical intervention and is difficult to manage conservatively. Epidural cortisone injections may be used, but provide limited pain relief and are of short duration. Radiofrequency (RF) lesioning of the medial branch of posterior primary ramus effectively denervates the facet joint and provides long-term, good-quality pain relief in selected patients. Facet rhizotomy has a success rate of 60-70 percent. Considering that little can be done for patients with chronic low back and/or neck pain other than medications and physical therapy, this success rate is quite acceptable. A successful RF facet rhizotomy usually gives pain relief for more than a year.