"MP$4me," the procedure is called a rhyzotomy (also called "radio frequency ablation" or " spinal nerve root denervation"). It is NOT radioactive. But, it is performed under radiological instrumentation (like fluoroscopy). The physician inserts a large-diameter needle into the the thecal area, near a spinal nerve root. Electricity is then used to destroy the nerve root. The high temperature achieved in this process has led people to call it "burning" a nerve root.
This process is typically quite painful, because very little anesthesia is used. The reason for this is because the physician needs the patient alert enough to describe how it feels during portions of the procedure. Therefore, only a small amount of local anesthetic is employed; and that is used only near the surface of the skin.
The success rate for a rhyzotomy is about 50-60%. It is somewhat higher for patients who have not had prior spine surgery. This and many other spinal procedures is described in the most comprehensive recent research here
www.painphysicianjournal.com/2009/july/2009;12;699-802.pdf.
The morbidity associated with a rhyzotomy is low. There is risk of nerve root impingement. And, as I mentioned, it is quite painful. But, the risk of complication is low. BTW, I had one many years ago. The result was a significant INCREASE in pain that lasted about a year.