The success rate for a facet rhyzotomy (you call it "burning the nerve") is about 60%, nearly the same success rate for spinal fusion. Here is the latrest comprehensive research on all major spinal treatment interventions:
http://www.painphysicianjournal.com/2009/july/2009;12;699-802.pdf . I had one that significantly
increased my pain forvever. The slight risk is needle nerve root impingement. Ask the physician how many of them he or she has done first.
I am somewhat mystefied (I've had DDD for 40 yeas, along with 4 failed spine surgeries, including multilevel fusion) with why your doctor would bring up having another fusion. Fusion exists for one purpose - to stabilize the spinal vertebra. Unless your fusion has had a disunion, why would he want to repeat it? Did your physican tell you that you have instability?
Each additional surgery will produce more damage to spinal nerve roots, the vertebra and nearby tissue. It increases the risk of future osteophytes (bone spur). Worse yet, each surgery creates more fibrosis (scarring). Fibrosis can impinge a nerve roots, just the same as an osteophyte or extruded disc. My last mylogram resembled a road map of New Jersey from all of the fibrotic tissue. I would want at least 3 spine surgeons to tell me that I had a disunion and instability before I would have have another fusion. Get some new opinions. A spine surgeon is a neurosurgeon or an orthopedic surgeon who has completed a fellowship in spine surgery. They can typically be found at or near teaching hospitals. Good luck.