A group of patients have chronic back pain due to arthritis in the cervical or the lumbar spine. It produces localized pain in the lower back, which radiates in the back of the leg, usually above the knees. Pain is dull aching nagging and gets worse with physical activity like bending lifting turning from side to side. Patient will undergo diagnostic lumbar facet injection or a small nerve block to the joint. If patient has a good (50-60%) improvement but short-lived from days to weeks, the patient may be a candidate for lumbar facet rhizotomy.
Rhizotomy can be done chemically, by phenol, by cryoneurolysis that is freezing the nerves or by radio frequency thermo coagulation that is cauterizing the small nerve fibers by heat. It is done under fluoroscopy with light sedation. Some physicians prefer to do it without any sedation.
The radio frequency needle is placed along the small nerve fiber that supplies the facet joints and needle is connected to radio frequency machine. The tip of the needle heats up around 80 degree Celsius, and gives a lesion (bite) of half to one centimeter along the nerve depending upon the size of the needle. Patient does not experience any sensory or motor loss in lower extremities.
Radio frequency thermo coagulation does not permanently disconnect the small nerves that grow back gradually, usually from six months to two years. If pain does return in the future, some patients may need a repeat rhizotomy procedure. In my experience, it usually lasts, on average, nine to ten months.
The patient does experience increased pain and soreness from the rhizotomy procedure for about two to three days, up to three weeks following the rhizotomy. I usually tell my patients that pain may get worse before they experience relief. The pain is usually caused by irritation of the nerves and muscle tissues, due to heat generated by radio frequency lesions.