Background and Objectives Facet interventions for spine pain have high failure rates, and preprocedural prediction of response is nearly impossible. A potential explanation may be aberrant central pain processing as that existing in conditions like fibromyalgia. To test this hypothesis, we conducted a retrospective study investigating the impact of having characteristics of fibromyalgia on the acute analgesic response to a first diagnostic medial branch block (MBB).
Methods We evaluated the analgesic responses of 187 patients that underwent MBB. Patients were categorized as “fibromyalgia-positive” or “fibromyalgia-negative” using the 2011 fibromyalgia survey criteria. Preprocedural and postprocedural pain scores and patient-completed pain diaries up to 24 hours postprocedure were collected. A linear mixed model was used to study longitudinal effects of MBB on pain responses.
Results Fibromyalgia-positive patients had a worse preprocedural pain phenotype (ie, greater pain severity, higher levels of depressive and anxiety symptoms, reduced function). Binary categorization of fibromyalgia status was not associated with a difference in immediate postprocedural pain relief; however, the longitudinal analgesic response across time varied significantly between groups (P = 0.0005). Fibromyalgia-negative subjects showed the expected steep decline in pain scores, followed by gradual return to baseline, whereas a more aberrant pattern was noted in the fibromyalgia-positive group. Pain scores for fibromyalgia-negative patients were also lower by −1.07 (SE = 0.37) on average after the MBB (P = 0.005).
Conclusions Characteristics of fibromyalgia may indicate pain that is more centralized in nature, a factor that may explain the aberrant analgesic response to this peripheral intervention. This may have implications for future prediction of treatment response, although prospective studies are needed.
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This study was performed at the Department of Anesthesiology, University of Michigan, Ann Arbor, MI.
This study was supported by the American Society of Regional Anesthesia and Pain Medicine Chronic Pain Research Grant (PI Brummett), with additional support from the Department of Anesthesiology, University of Michigan, Ann Arbor, MI.
Preliminary results were presented at Anesthesiology 2012: American Society of Anesthesiologists 2012 Annual Meeting, held October 13–17, 2012, in Washington, DC.
Dr Brummett receives research funding from Neuros Medical Inc. (Willoughby Hills, OH). Dr Hassett receives research funding from Bristol-Myers Squibb and Pfizer. In addition, Dr Hassett is a consultant for Lexicon Pharmaceuticals and Precision Health Economics. There are otherwise no relevant disclosures.
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