Facet rhizotomies are relatively safe but this really depends upon the experience and care of the treating physician. C2-3 and C3-4 facets are the most common of all the facet treatments I order.
Ablation depends upon normal anatomy. The “burn zone” from the treatment probe in my understanding is about 3-4 mm. If the nerve is not in a normal anatomic position, the burn zone may “miss” the nerve. If the nerve is in the outside edge of the zone where a partial burn occurs, this could theoretically damage the nerve without fully destroying it.
In my experience, this procedure works about 75% of the time. There are a small subset of patients that become worse but normally, the flair-up of symptoms resolve in about three months. About 30% of patients need a repeat rhizotomy after about one year due to the nerves attempt to grow back.
Pulsed ablation in my understanding is more common in the thoracic spine where the medial branch nerves are much closer to the origins of the roots and there is some increased concern of injury. In my experience, pulsed frequency is less effective.
Cat scans may not be necessary in the case of facet originated pain. Sometimes, the facets may not look too degenerated but still will cause pain. Using the X-rays, MRI and a good physical examination should reveal facet mediated pain in the majority of cases. There are circumstances that CT scan is valuable but less than you might think.