The Elevated Serum Level of IFN- 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-, IL-1, IL-6, TNF-, IL-10, and TGF- 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- and other cytokines in neuropathic pain (NP) development.

MATERIALS AND METHODS

Clinical and biochemical assessment was conducted in four groups of patients: consisted of 24 FBSS patients qualified to SCS therapy, included 17 patients who were one month after implantation, featured 12 patients who were 3 months after the implantation, and (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- were ascertained by an immunoenzymatic method.

RESULTS

We found a significant difference between the patients before SCS and controls' serum level of IFN-. Similarly, a significantly higher level of TNF- 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- and other cytokines. We noticed a positive correlation between IFN- concentration with NRS back value before SCS and positive correlation between IFN- concentration after SCS with NRS leg value before SCS. Higher IFN- concentrations accompanied higher NRS values. Levels of TGF- and IL-10 may correlate with physical ability and depressive behavior.

CONCLUSIONS

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