Prognostic factors for recovery in radicular pain caused by lumbar disc herniation

Lumbar radicular pain constitutes only 5%-10% of low back pain conditions, but it accounts for 33% of the sick leave and 47% of the disability benefits due to back pain in Norway. Previous data show that the recovery from lumbar radicular pain may be influenced by physical, psychosocial, surgery-related and clinical factors. In addition, genetic factors can influence on the development of disc degeneration and the recovery after symptomatic disc herniation.\nThe fact that inflammation contributes to the pathogenesis of disc herniation and radicular pain is now well established. The inflammatory response, initiated from the annulus fibrosus in case of disc herniation, may lead to increased levels of pro-inflammatory interleukins (ILs) close to nerve roots. This inflammatory process could also promote Modic changes.\nIn this thesis, the role of such cytokines and genetic factors in recovery from lumbar radicular pain was addressed. The present data demonstrated a significant association between the inflammatory serum cytokine IL-6 and functional recovery from symptomatic disc herniation. Moreover, the genotype IL-1a C>T rs1800587 increased the risk of persistent pain 1-year after disc herniation. Regarding the radiological factors, we showed that type I Modic changes influences the short-term clinical outcome in patients with low back pain and radicular pain. A sex dependent effect of the opioid receptor mu 1 (OPRM1 A118G) rs1799971 genotype on recovery after disc herniation was also identified.\nIt is concluded that inflammatory, radiological and genetic factors may be important for the recovery after lumbar disc herniation.