Cervical medial branch block progression to radiofrequency neurotomy: A retrospective clinical audit

BACKGROUND: Chronic axial neck pain (CANP) due to zygapophysial joint arthropathy is best diagnosed via cervical medial branch block (MBB). However, the paradigm by which MBB is used to select patients for cervical radiofrequency neurotomy (RFN) is contested. Dual diagnostic cervical MBB with a minimum of ≥80% pain relief to diagnose cervical zygapophysial joint pain has been accepted by some Medicare Local Coverage Determinations as the method for selecting patients for cervical RFN. There are some who would argue that the utility of the dual diagnostic MBB and the ≥80% pain relief cut off lacks utility in clinical practice. The suspicion being those who progress from MBB1 to MBB2 will then flow from MBB2 to RFN without fail. Does clinical practice using dual diagnostic MBBs and using an ≥80% pain relief cut off reduce patient eligibility for cervical RFN after both MBB1 and MBB2? METHODS: A retrospective clinical audit was carried out at an academic institution spine center from January 1(st) to December 31st, 2019. Charts were selected based on Current Procedural Terminology codes for MBB, then included if the cervical medial branches were targeted. Charts were then reviewed for procedural progression. RESULTS: 21/51 (24%, 95% Confidence Interval 12-35%) patients progressed from MBB1 to MBB2. Of those 21 patients, 13 patients progressed from MBB2 to RFN (62%, 95% CI 41-83%). In total, 13/51 (14%, 95% CI 14-37%) patients who were initially suspected to have CANP due to zygapophysial joint pain progressed to RFN. Both MBB1 and MBB2 hindered the progression of 30/51 patients (59%, 95% CI 45-72%) and 8/21 patients (38%, 95% CI 17-59%), respectively. CONCLUSION: Both MBB1 and MBB2 served to filter patients from progression to RFN using dual MBBs with an ≥80% pain relief cutoff.