Ask Dr. Z

"Treatment is: R&L - L3, L4 & L5 - medial branch neurotomy. The L5 posterior ramus was lesioned at the junction of the sacral ala & root of the superior articular process of S1. RF curved probe was placed under fluoroscopic guidance. Impedances were appropriate & sensory testing c/w proximity to medial branch nerves. Testing was carried out to check proximity of probe to motor nerve and all were negative. The patient was then exposed to 1, 90 thermal RF @ 80 C. In order to treat the involved (2) levels L3-L4 & L4-L5 it was necessary to address each of the following three lumbar medial branch nerves: L3, L4, & L5." 

Can you resolve a debate? Some of us coded this as: 64635-50, 64636 & 64636-XS. Others coded it as: 64635-50 & 64636 x4. Please indicate the correct coding and if -KX modifier is required.