Radio frequency denervation for facet joint pain
This technique targets the small nerves which supply the facet joints in the back. If the nerve can be damaged or destroyed, perhaps some level of pain relief could be expected.
The nerves in this area are divided into the medial (inside) branches and the lateral (outside) branches. In the low back, the medial branches are responsible for conducting pain signals from the facet joints, the lateral branches conducting pain from the sacro-iliac joints. They do not control muscle contraction (except for small back muscles which are not very important) or feelings in the arms or legs so these cannot be damaged.
Before this procedure is decided upon, it is important to decide if the target joints are actually the source of the patient’s pain. Diagnostic injections with an anaesthetic drug should reduce or abolish the typical pain, and if this is effective for a while then radio-frequency denervation may be helpful
Radio frequency denervation or neurotomy (neurotomy = cutting a nerve) is a specialized form of injection or blocking procedure. Heat damage (referred to as a lesion) is created on the nerves thought to be responsible for the pain, with the aim of cutting pain signals along this nerve. This should relieve pain, at lease until the nerve regenerates.
Success of radio frequency denervation
This procedure can provide pain relief lasting from nine to fourteen months and perhaps longer. Then the nerve tends to regenerate and the pain may return. Success rates vary from about 30% to 50% of patients experiencing significant pain relief up to two years. About half of the remaining patients will get some pain relief for a shorter period. Some patients do not experience any pain relief.
The radio frequency denervation procedure
Radio frequency denervation is performed under fluoroscopy (a form of live x-ray). It is important to be sure that the placement of the needle is accurate, to damage the correct small nerve and avoid unintended consequences.
Patients are advised to avoid driving and strenuous activities for the day of the procedure, and to continue taking their normal medications except aspirin or other blood-thinning medications.
An intravenous line is inserted so that relaxation drugs can be given as required and the patient asked to lie face down on the x-ray table.
A local anaesthetic is given to the area of skin where the procedure is to be performed. Fluoroscopy, which is live x-ray guidance, is used to place the needle alongside the medial or lateral branch nerves. A small electrical charge is passed through the needle to check it is in the right area next to the nerve. This stimulation should bring on the patient’s typical pain and make the back muscles twitch.
The target nerves are then anaesthetized to minimize the pain while the lesion is being made, and repeated as often as the number of nerves to be treated. The whole thing takes from 30-90 minutes.
Follow up after facet joint denervation
The next day, the patient can return to regular activities, with care. The neck or back is often very sore over the next one to four days, caused by muscle spasm and irritability while the targeted nerves are dying from the heat damage over the next one to two weeks. Resting for a few days before resuming normal activities is normal, with painkilling medication given as appropriate.
Full pain relief is usually developed about two to three weeks after the procedure, by which time the nerves have completely died. The back or neck may feel odd or slightly weak for several weeks after.
The nerves will eventually grow back with time, but the pain may or may not come back, and if it does, a second procedure can be performed. In some cases the pain never returns.
Worries about facet joint denervation
People worry they will injure or over strain the joints as they are unable to feel them after the nerves have been heat damaged. This has not been found to occur, even with the very large number of these procedures which have been performed.
There is a small chance, less than 5%, that the pain will worsen after the procedure. This may be due to increased irritation of a partially damaged nerve, which was not completely destroyed. Treatment with medication can help this and it usually goes away in several months.
Complications of radiofrequency denervation
Complications are uncommon but do occur, and include pain or discomfort around the injection site, numbness of the skin in the same area, increased pain from muscle spasm in the injection area, permanent nerve pain, allergies or reactions to the medication and infection.