fMRI-study in Patients With Small Fiber Neuropathy

Small fiber neuropathy (SFN) is a form of peripheral neuropathy, which is characterized by neuropathic pain and autonomic dysfunction. Mutations in SCN9A, the gene encoding for the voltage-gated sodium channel NaV1.7, are associated with SFN. SCN9A-associated SFN often results in chronic neuropathic pain, which is difficult to treat. Chronic neuropathic pain may cause structural and functional changes in the brain. Until now, only one small study examined the structural and functional changes of the brain in SFN patients. No studies have been performed in strictly defined SFN patients. Therefore, it would be interesting to explore whether in SFN patients with an SCN9A mutation, the genotype will lead to a distinct brain activation pattern on functional MRI (fMRI) and if the integrity or structural connectivity of the brain is altered using diffusion tensor imaging (DTI). This may provide a better understanding of the pathophysiological pathways for chronic pain and might serve as a biomarker for evaluating therapy. The objective of this study is to explore whether there is an indication whether patients with SCN9A-associated SFN have an abnormal brain activation pattern on resting state fMRI and during advanced thermal stimulation and altered structural connectivity on DTI versus SFN patients without a mutation and versus age- and gender-matched healthy controls. With this knowledge, objective pain measurement for patients with SFN may serve as a biomarker in evaluating efficacy of targeted therapy.