Concordant pain provocation during transforaminal epidural steroid injection for lumbosacral radiculopathy: effect on pain outcome and predictive factors.

BACKGROUND Anecdotal report suggests that provocation of pain during epidural steroid injection (ESI) that is concordant with typical radicular symptoms predicts pain outcome following injection. However, limited evidence exists that substantiates this theory. Additionally, there is a paucity of literature investigating factors associated with the provocation of pain during ESI. OBJECTIVES The goal of this study was to determine whether provocation of concordant radicular pain during transforaminal ESI predicts pain relief immediately after injection and at short-term follow-up. Demographic, radiologic, and procedural factors associated with the pain provocation and pain outcomes at immediate and short-term follow-up were also investigated. STUDY DESIGN Longitudinal cohort study. SETTING Urban academic outpatient interventional spine clinics. METHODS Adults who underwent a fluoroscopically guided transforaminal ESI without sedation between January 1, 2006, and October 29, 2007, for the treatment of lumbosacral radicular pain were included in this study. The relationships between provocation of concordant pain, immediate post-injection, and follow-up visual analogue scale (VAS) pain scores, as well as with demographic, radiologic, and procedural factors were determined using chi-square/Fisher's exact tests for categorical variables and t-tests or ANOVA for numerical variables. RESULTS One thousand twenty one patients, 42.4% (433) male/57.6% (588) female, with a mean (SD) age of 54.1 (16.7) years were included in the study. Concordant pain provocation did not predict the magnitude of pain reduction (P = 0.9255) or the frequency of achieving > 50% pain relief (P = 0.7449) at short-term follow-up. Radiologic evidence of foraminal stenosis or nerve root impingement (P < 0.0001) and the lack of a medial-superior contrast flow pattern (P = 0.0199) were associated with a greater frequency of pain provocation during transforaminal ESI. LIMITATIONS This study is primarily limited by possible selection bias given that patients who did not follow-up in the clinic could not be studied, and an incomplete follow-up rate (66%). Conclusions regarding subacute and long-term pain outcomes cannot be determined from this study as only short-term data were available. CONCLUSIONS Provocation of concordant radicular pain does not predict pain relief at short-term follow-up after a transforaminal ESI. Foraminal stenosis, nerve root impingement, and lack of a medial-superior contrast flow pattern are associated with pain during the transforaminal ESI. Thus, clinicians should be aware of these radiologic and procedural risk factors for inciting pain during transforaminal ESI.