IFN-γ Correlations with Pain Assessment, Radiological Findings, and Clinical Intercourse in Patient after Lumbar Microdiscectomy: Preliminary Study

Abstract

Objectives. We investigated the influence of pain decrease after lumbar microdiscectomy on the interferon gamma (IFN-γ) serum level in patients with lumbar disc herniations. The study challenges the mechanism of sciatica pain and the role of IFN-γ in radicular pain development. Material and Methods. We performed clinical and immunoenzymatic assessment in a group of 27 patients with lumbar radicular pain due to disc herniations before and 3 months after surgery. Clinical status was assessed with the use of the Numeric Rating Scale (NRS), the Pain Rating Index and Pain Intensity 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 observe significant correlations between the results of the pain in the back region assessment NRS back scale after the surgery with the level of IFN-γ before the procedure ( $r_s=0.528$ ; $p=0.008$ ) and after the procedure ( $r_s=0.455$ ; $p=0.025$ ). These are moderate and positive correlations—the decrease in pain is correlated with the lower IFN-γ level. Additionally, there are significant correlations between the results of the PRI scale and the IFN-γ level. The PRI score before surgery correlates positively with IFN-γ after surgery ( $r_s=0.462$ ; $p=0.023$ ), and the PRI score after surgery correlates positively with IFN before surgery ( $r_s=0.529$ ; $p=0.005$ ) and after surgery ( $r_s=0.549$ ; $p=0.003$ ). All correlations are moderate in severity—severe pain before surgery correlates with a higher level of IFN-γ after surgery and also higher IFN-γ before surgery. There were significant differences in the IFN-γ level before ( $Z=-2.733$ ; $p=0.006$ ) and after ( $Z=-2.391$ ; $p=0.017$ ) surgery in the groups of patients with and without nerve compression. In the group of patients with nerve compression, the level of IFN-γ before and after surgery was lower. Conclusions. Less pain ratio after operation correlates with the level of IFN-γ. In the group of patients without significant nerve compression confirmed by MRI scans, the level of IFN-γ before and after surgery was higher than that in the group with nerve root compression.