Elevated serum inflammatory markers in post-poliomyelitis syndrome

ObjectivesTo determine (i) whether serum inflammatory markers TNFα, IL-1β. IL-6, and leptin are increased in post-poliomyelitis syndrome (PPS) compared to healthy controls; and (ii) whether an association exists between elevated inflammatory markers and clinical parameters in PPS. The cause of PPS is unknown, but abnormal inflammatory responses have been implicated in several small studies.MethodsSerum inflammatory markers were measured (by Luminex) in 51 PPS patients and 26 normal controls. Clinical parameters assessed included disease duration, muscle strength (Medical Research Council sumscore), fatigue (Fatigue Severity Scale and Multidimensional Fatigue Inventory), and pain (visual analog scale scores).ResultsIn PPS, TNFα levels, as well as IL-6 and leptin were significantly increased compared to controls (Wilcoxon rank-sum test, p = 0.03 for TNFα, p = 0.03 for IL-6, p = 0.01 for leptin). The elevated TNFα levels in PPS were associated with increased pain due to illness (Spearman correlation coefficient r = 0.36, 95% C.I. 0.09 to 0.57) and specifically, with muscle pain (r = 0.38, 95% C.I. 0.11 to 0.59). There were no correlations between inflammatory markers in PPS and joint pain, muscle strength, fatigue, or disease duration.ConclusionsSerum TNFα, IL-6 and leptin levels are abnormally increased in PPS patients. Elevated TNFα levels appear to be specifically associated with increased muscle pain.