Predictive value of receptive fields for persistence of pain after spinal surgery ? a cohort study

F. TREICHEL; J. A. BIURRUN MANRESA; M. MÜLLER; L. ARENDT-NIELSEN; O. K. ANDERSEN; P. JÜNI; M. CURATOLO

Vienna

Congreso; 9th Congress of the European Pain Federation EFIC; 2015

European Pain Federation EFIC

Background and aim: Failed back surgery is a largely unresolved clinical issue. Central hypersensitivity is a potential determinant of persistent postoperative pain. The area of Reflex Receptive Fields (RRF) is a novel method to assess central hypersensitivity. The RRF denotes the area of the foot sole from which spinal nociceptive reflexes (NWR) can be elicited. The aim was to evaluate the predictive value of the RRF area for failed back surgery.Methods: We performed a prospective cohort study in patients undergoing spinal surgery and compared the RRF area in patients with failed and non-failed back pain surgery at two month?s follow-up. Treatment failure was defined as less than 30% reduction from baseline pain. NWR were evoked by electrical stimulation at ten sites on the foot sole. RRF was defined as the skin area from which a NWR could be evoked following a pre-defined detection criterion. We tested the hypothesis that the size of the RRF area is larger in failed back surgery patients, as compared with non-failures. The data were analyzed by Student?s-t-test.Results: We included 111 patients who underwent low back spinal surgery. 17% of all patients showed treatment failure two months after surgery. Failures showed a mean RRF area of 0.327 (SD 0.206), which was not significantly different from non-failure patients with a mean RRF area 0.328 (SD 0.207), p=0.99.Conclusion: Central hypersensitivity as detected by an expansion of RRF area is unlikely toexplain persistent pain two months after spinal surgery.