CLaSSICO study CentraL SenSitisation In patients with Chronic lOw back pain radiating to the leg undergoing segmental nerve root blocks : Study protocol

Background There is growing evidence for an important role of central sensitization (CS) in the development and maintenance of chronic pain. This accounts for patients with chronic low back pain radiating to the leg (CLBPr) as well. Care as Usual (CaU) in these patients consists of diagnostic segmental nerve root blocks (dSNRB) followed by therapeutic interventions, i.e. a therapeutic segmental nerve root block (tSNRB) or pulsed radiofrequency (pRF). However, it is unknown if these procedures affect the amount of CS in these patients. Aim The aim of the present study is to determine the alterations in the presentation of CS in CLBPr patients during care as usual. Hypothesis A decrease in pain measured by NRS correlates with a decrease in CS (signs) in CLBPr patients undergoing SNRBs Method/design Case control study in 50 patients with CLBPr, for whom the physician is considering dSNRB and tSNRB or pRF, and 50 sex- and age-matched healthy controls. Following care as usual protocol, patients will receive dSNRB and tSNRB or pRF. Healthy control subjects will not undergo any procedure. The study has three to five visits,depending on the number of dSNRBs performed (max. 3). Evaluation The bedside examination and questionnaires that are part of CaU will be extended with QST and CSI, NRS, PCS and PVAQ. The measurements will take place just before the dSNRBs, the tSNRBs or pRF and a follow-up four weeks after the intervention. Data collection will take 1 year