Lumbosacral Radiculopathy: Inciting Events and Their Association with Epidural Steroid Injection Outcomes.

OBJECTIVE: Low back pain is the leading cause of worldwide disability, with lumbosacral radiculopathy accounting for over one-third of these cases. There are limited data on the relationship between etiologies and lumbosacral radiculopathy, and it is unknown whether specific causes predict treatment outcomes. DESIGN, SETTING, AND SUBJECTS: This study explores patient-reported etiologies for lumbosacral radiculopathy in a chronic pain clinic between January 2007 and December 2015 and examines whether these causes affected epidural steroid injection outcomes. METHODS: We reviewed the medical records of 1,242 patients with lumbosacral radiculopathy who received epidural steroid injections. The recording of an inciting event was done contemporaneously based on note templates. A positive outcome following an epidural steroid injection was defined as ≥30% pain relief sustained for six or more weeks without additional intervention. Factors associated with epidural steroid injection outcome were analyzed by multivariable logistic regression. RESULTS: Fifty point seven percent reported an inciting event, and 59.9% of patients experienced a positive epidural steroid injection outcome. The most commonly reported causes were falls (13.1%), motor vehicle collisions (10.7%), and lifting (7.8%). Individuals with a herniated disc (56.3%) were more likely to report a precipitating cause than those with stenosis (44.7%) or degenerative discs (47.8%, P = 0.012). An inciting event did not predict treatment outcome. Factors associated with negative treatment outcome included opioid consumption (odds ratio [OR] = 0.61, 95% confidence interval [CI] = 0.39-0.95, P = 0.027), secondary gain (OR = 0.69, 95% CI = 0.50-0.96, P = 0.030), and baseline pain score (OR = 0.90, 95% CI = 0.84-0.97, P = 0.006). The number of levels injected was associated with a positive outcome (OR = 2.72, 95% CI = 1.28-6.47, P = 0.008). CONCLUSIONS: Reported inciting events are common in patients with lumbosacral radiculopathy but are not associated with outcome following epidural steroid injection, and their occurrence is not always consistent with the purported mechanism of injury.

Analgesic effectiveness of methoxyflurane inhaler during genicular nerve block in knee osteoarthritis: a randomized controlled trial.

BACKGROUND: Up to 30% of patients with knee osteoarthritis (KOA) have evidence of sensitization, with a similar proportion experiencing severe pain during procedures. Most patients with KOA are elderly and often develop side effects from intravenous sedation. Our study investigated the effectiveness of a methoxyflurane inhaler combined with local anesthesia in reducing procedural pain from genicular nerve block compared with local anesthesia alone. METHODS: 42 adults with refractory KOA were randomized into two groups. Methoxyflurane group received a self-titrated methoxyflurane inhaler with local anesthesia whereas lidocaine group received local anesthesia only. The primary outcome was pain score on a 0-10 verbal numerical rating scale (VNRS) during the procedure. Secondary outcomes included changes in VNRS and behavioral pain scale (critical care pain observational tool) during the procedure, hemodynamic changes, anxiety level, sedation score, and adverse events. RESULTS: 42 patients with a mean age of 66±12 years participated in this study. There were no significant baseline differences. During the procedure, the methoxyflurane group experienced a significantly greater VNRS pain reduction from baseline (2 (1, 4) vs -1 (-2, 0); p<0.01) and greater VNRS reduction over time (p=0.01) compared with the lidocaine group, with a higher sedation score (p<0.01). Immediately postprocedure, anxiety levels were lower in the methoxyflurane group compared with the lidocaine group (median State-Trait Anxiety Inventory score 21 (IQR 20, 24) vs 27 (23, 29); p=0.02), but the median reduction in anxiety level was not significant (6 (1, 12) vs 5 (0, 14); p=0.61). There were no differences in behavioral pain scores, hemodynamic parameters, recovery or discharge times, and adverse effects between the two groups. CONCLUSION: A methoxyflurane inhaler combined with local anesthesia provided better procedural pain control than local anesthesia alone with no observable differences in adverse effects. Future studies evaluating the impact of a methoxyflurane inhaler on different types of painful procedures are warranted.

Establishing an optimal "cutoff" threshold for diagnostic lumbar facet blocks: a prospective correlational study.

OBJECTIVES: Diagnostic medial branch blocks (MBB) are considered the reference standard for diagnosing facetogenic pain and selecting patients for radiofrequency (RF) denervation. Great controversy exists regarding the ideal cutoff for designating a block as positive. The purpose of this study is to determine the optimal pain relief threshold for selecting patients for RF denervation after diagnostic MBB. METHODS: In this multicenter, prospective correlational study, 61 consecutive patients undergoing lumbar facet RF denervation after experiencing significant pain relief after MBB were enrolled. A positive outcome was defined as a ≥50% reduction in back pain at rest or with activity coupled with a positive satisfaction score lasting longer than 3 months. The relationship between pain relief after the blocks and denervation outcomes was evaluated by pairwise correlation matrix, receiver's operating characteristic curve, and stratifying outcomes based on 10- and 17-percentage point intervals for MBB. RESULTS: There were no significant differences in RF outcomes based on any MBB pain relief cutoff over 50%. A trend was noted whereby those patients who obtained <50% pain relief reported poorer outcomes. No optimal threshold for designating a diagnostic block as positive, above 50% pain relief, could be calculated. CONCLUSION: Employing more stringent selection criteria for lumbar facet RF is likely to result in withholding a beneficial procedure from a substantial number of patients, without improving success rates.