Distinct Functional Connectivity Patterns for Intermittent Vs Constant Neuropathic Pain Phenotypes in Persistent Spinal Pain Syndrome Type 2 Patients.

Abstract

Chronic low backpain (cLBP) has been associated with alterations in brain functional connectivity (FC) butbased upon heterogeneous populations and single network analyses. Our goal is to study a more homogeneous cLBP population and focus on multiple cross-network (CN) connectivity analysis. We hypothesize that within this population: 1) altered CNFC, involving emotion and reward/aversion functions are related to their pain levels and 2) altered relationships are dependent upon pain phenotype (constant neuropathic vs intermittent pain). In this case series, resting state fcMRI scans were obtained over a study duration of 60 months from 23 patients (13 constant neuropathic and 10 intermittent pain) with Persistent Spinal Pain Syndrome (PSPS Type 2) being considered for spinal cord stimulation (SCS) therapy at a single academic center. Images were acquired using a Discovery MR750 GE scanner. During the resting state acquisitions, they were asked to close their eyes and relax. The CNanalysis was performed on 7 brain networksand compared to age-matched controls. Linear regression was used to test the correlation between CN connectivity and pain scores. CNFCinvolving emotion networks (STM: striatum network index) was significantly lower than controls in all patients, regardless of pain phenotype (P < 0.003). Pain levels were positively correlated with emotional FCfor intermittent painbut negatively correlated for constant pain. This is thefirst report of 1) altered CN FCinvolving emotion/reward brain circuitry in 2) a homogeneous population of cLBPpatients with 3) two different pain phenotypes (constant vs intermittent) in PSPS Type 2 patients being considered for SCS. FC patterns were altered in cLBPpatients as compared to controls and were characteristic for each pain phenotype. Thesedata supportfcMRI as a potential and objective tool in assessing pain levels in cLBP patients with different painphenotypes.