Is transcranial direct current stimulation an effective predictor for invasive occipital nerve stimulation treatment success in fibromyalgia patients?

Abstract

Background Fibromyalgia is a disorder distinguished by pervasive musculoskeletal pain that has pervasive effects on affected individuals magnifying the importance of finding a safe and viable treatment option. Objective The goal of this study is to investigate if transcranial direct current stimulation (tDCS) treatment can predict the outcome of occipital nerve field stimulation (ONFS) via a subcutaneous electrode. Methods Nine patients with fibromyalgia were selected fulfilling the American College of Rheumatology-90 criteria. The patients were implanted with a subcutaneous trial-lead in the C2 dermatome innervated by the occipital nerve. After the treatment phase of ONFS using a C2 implant, each patient participated in three sessions of tDCS. Stimulation outcomes for pain suppression were examined between the two methods to determine possible correlations. Results Positive correlation of stimulation effect was noted between the numeric rating scale changes for pain obtained by tDCS treatments and short-term measures of ONFS, but no correlation was noted between tDCS and long-term ONFS outcomes. A correlation also was noted between short-term ONS C2 implant pain suppression and long-term ONS C2 implant treatment success. Conclusions This pilot study suggests that tDCS is a predictive measure for success of OFNS in short-term but cannot be used as a predictive measure for success of long-term OFNS. Our data confirm previous findings that ONFS via an implanted electrode can improve fibromyalgia pain in a placebo-controlled way and exert a long-term pain suppression effect for ONFS via an implanted electrode.