Case report: The promising application of dynamic functional connectivity analysis on an individual with failed back surgery syndrome

Abstract

Failed back surgery syndrome (FBSS), a chronic neuropathic pain condition, is a common indication for spinal cord stimulation (SCS). However, the mechanisms of SCS, especially its effects on supraspinal/brain functional connectivity, are still not fully understood. Resting state functional magnetic resonance imaging (rsfMRI) studies have shown characteristics in patients with chronic low back pain (cLBP). In this case study, we performed rsfMRI scanning (3.0 T) on an FBSS patient, who presented with chronic low back and leg pain following her previous lumbar microdiscectomy and had undergone permanent SCS. Appropriate MRI safety measures were undertaken to scan this subject. Seed-based functional connectivity (FC) was performed on the rsfMRI data acquired from the FBSS subject, and then compared to a group of 17 healthy controls. Seeds were identified by an atlas of resting state networks (RSNs), which is composed of 32 regions grouped into 8 networks. Sliding-window method and k-means clustering were used in dynamic FC analysis, which resulted in 4 brain states for each group. Our results demonstrated the safety and feasibility of 3T MRI scanning in a patient with implanted SCS system. Compared to the brain states of healthy controls, the FBSS subject presented very different FC patterns in less frequent brain states. The mean dwell time of brain states showed distinct distributions: the FBSS subject seemed to prefer a single state over the others. Although future studies with large sample sizes are needed to make statistical conclusions, our findings demonstrated the promising application of dynamic FC to provide more granularity with FC changes associated with different brain states in chronic pain.

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

“…16,19,23,27,29 However, in contrast to our previous study, 19 these studies have had several limitations such as 1) heterogenous populations of patients; 16 2) limited number of patients; 23 3) lack of analysis of subcortical regions; 23,27 4) lack of comparison to controls 16,23,27 or 5) lack of cross-network analysis. 16,23,27,29 Limitations/Future Directions…”

“…7,20 However, these reports were based upon heterogeneous cLBP populations with different etiologies and pain phenotypes (neuropathic vs nociceptive; constant or intermittent). Several groups have also explored the supraspinal effects of spinal neuromodulation for pain, 16,[22][23][24][25][26][27][28][29][30] recently reviewed in 31 In addition, a few recent fcMRI studies on chronic pain patients with implanted SCS systems have been presented. 16,19,23,27,29 However, in contrast to our previous study, 19 these studies have had several limitations such as 1) heterogenous populations of patients; 16 2) limited number of patients; 23 3) lack of analysis of subcortical regions; 23,27 4) lack of comparison to controls 16,23,27 or 5) lack of cross-network analysis.…”