The Elevated Serum Level of IFN- γ in Patients with Failed Back Surgery Syndrome Remains Unchanged after Spinal Cord Stimulation.

Objectives: We investigated the influence of spinal cord stimulation (SCS) on IFN- γ , IL-1 β , IL-6, TNF- α , IL-10, and TGF- β serum levels in failed back surgery syndrome (FBSS) patients. The study will try to give new insights into the mechanism of SCS action and the role of IFN- γ and other cytokines in neuropathic pain (NP) development.

Materials and Methods: Clinical and biochemical assessment was conducted in four groups of patients: group 0 consisted of 24 FBSS patients qualified to SCS therapy, group 1 included 17 patients who were one month after implantation, group 2 featured 12 patients who were 3 months after the implantation, and group C (the control group) with no NP. Clinical status was assessed with the use of Numeric Rating Scale (NRS), the Pain Rating Index of McGill Pain Questionnaire (SF-MPQ), the Oswestry Disability Index (ODI), and Beck Depression Inventory (BDI). The plasma concentrations of IFN- γ were ascertained by an immunoenzymatic method.

Results: We found a significant difference between the patients before SCS and controls' serum level of IFN- γ . Similarly, a significantly higher level of TNF- α and significantly lower level of IL-10 in FBSS patients than controls were observed. The significant differences were not observed between SCS patients 3 months after the procedure and controls' serum level of IFN- γ and other cytokines. We noticed a positive correlation between IFN- γ concentration with NRS back value before SCS and positive correlation between IFN- γ concentration after SCS with NRS leg value before SCS. Higher IFN- γ concentrations accompanied higher NRS values. Levels of TGF- β and IL-10 may correlate with physical ability and depressive behavior.

Conclusions: SCS did not influence serum cytokine levels significantly. Serum concentration of IFN- γ may be recognized as an occasional pain factor because of its significantly higher level in FBSS patients versus controls and higher IFN- γ value accompanying higher pain intensity.