Indications for Repeat Diagnostic Medial Branch Nerve Blocks Following a Failed First Medial Branch Nerve Block

Abstract

No studies have directly measured the false negative rate of medial branch block (MBB) with correlation to medial branch neurotomy (MBN) outcome. We investigated the potential false negative MBB rate and the subsequent MBN outcome on a consecutive audit of all patients undergoing a double MBB protocol. We prospectively collected audit data and retrospectively collected data by phone on 229 consecutive patients undergoing diagnostic MBB. One-hundred-twenty-two patients reporting greater than 50% of subjective pain relief subsequently underwent either MBN or a confirmatory block followed by MBN. A total of 55 patients underwent a second confirmatory MBB and within that group 27.3% (15/55) reported less than 50% relief post initial MBB and 30.9% (17/55) between 50% and 69% relief. We performed an in-depth analysis of these 2 subgroups focusing on the reason a second MBB was performed despite a “negative” or “indeterminant” first MBB. We divided the “negative” responders to the first MBB into those reporting < 50% relief (Group 1) and those reporting between 50% and 69% relief (Group 2). We calculated a potential 46.7% false negative rate in Group 1 and 47.1% false negative in Group 2; however, the false negative results in Group 1 were predominately in those patients reporting delayed relief of pain and those re-blocked greater than 2 years after the first MBB. The success rate in all patients undergoing MBN was 87% compared to the 75% relief in the false negative groups with no statistically significant difference. In summary, the false negative rate for patients reporting less than 50% relief post MBB is probably less than 20% although there is a high “apparent negative” responds in patients reporting delayed relief or in those who had a second block 2 or more years post initial MBB. Patients reporting between 50 and 69% pain relief have a false negative response rate of 47.1% and should be considered for a confirmatory block. Key words: Facet rhizotomy, zygapophyseal joint, low back pain, chronic pain, facet joint, radiofrequency neurotomy, medial branch block, medial branch neurotomy

Ultrasound-guided lumbar medial branch blocks and intra-articular facet joint injections: a systematic review and meta-analysis

“… 8 , 38 , 39 , 42 The false-negative rate may be magnified by imaging modalities that miss the target nerve or cannot reliably detect intravascular uptake. 11 The findings of this meta-analysis suggest that US-guided MBB could further impede the ability to accurately identify patients for radiofrequency denervation. However, use of US may be indicated in austere environments or select clinical scenarios where avoiding radiation exposure is a key outcome.…”

Consensus practice guidelines on interventions for lumbar facet joint pain from a multispecialty, international working group

“…5 For diagnostic criteria, research and review articles abound on the ideal cut-off for designating a block as positive, and the optimal number of blocks that should be performed before lumbar facet radiofrequency ablation (RFA) treatment, with no consensus emerging. [6][7][8][9][10][11] Lumbar facet interventions comprise the second most common procedure performed in interventional pain practices, with millions per year being performed in the USA alone. 12 For lumbar RFA, a recent review of the Marketscan commercial claims and encounters databases from 2007 to 2016 demonstrated a 130.6% overall increase in utilization (9.7% annually).…”

Consensus practice guidelines on interventions for cervical spine (facet) joint pain from a multispecialty international working group

“…The rationale for the lumbar facet guidelines to recommend single blocks was based in large part on the incidence of false-negative blocks of the lumbar medial branch nerves, which were estimated to be 47% in a retrospective study by Derby et al [ 299 ] using either 50% (46.7%) or 70% (47.1%) cut-off thresholds. In this study, among the eight patients with initial false-negative blocks who underwent lumbar medial branch RFA after a positive subsequent block, six (75%) experienced a positive outcome.…”