Chronic pain is a complex neurological disease that adversely impacts function and
quality of life. Brain structure and function are altered when an individual is in the
chronic pain state. Furthermore, chronic pain is associated with disruptions in
functional brain connectivity. Spinal cord stimulation (SCS) is a clinically available
non-pharmacological therapy that is used in the management of chronic pain. Although SCS
is effective for many, there are individuals who do not benefit. Therefore, in order to
better understand brain mechanisms that underlie SCS treatment of chronic pain and to
develop brain biomarkers of SCS efficacy, the investigators propose to evaluate
functional brain changes in response to SCS. Finding a brain signature of pain relief in
response to SCS would improve understanding of how SCS alleviates chronic pain and may
help to identify those most likely to respond. The main objective of this study is to
assess changes in brain connectivity in response to SCS in individuals with chronic
neuropathic pain. The investigators will study two cohorts: Cohort 1 - na�ve to SCS
patients who are undergoing SCS trial period; Cohort 1 - long-term SCS users ( 6 months
post implantation). The investigators aim to identify neurophysiological brain signatures
of pain relief in these two populations using resting state Near Infrared Spectroscopy
and Electroencephalography (rs-fNIRS/EEG). Study Design: The investigators will enroll
Veterans with refractory chronic neuropathic pain who are currently receiving clinical
care within the medical center. Cohort 1: Individuals with chronic neuropathic pain who
are na�ve to SCS and were selected for SCS trial period as part of their clinical care
will participate in two study visits: before the beginning of the SCS trial and the end
of the trial period. Data collection will be consistent across all data collection
timepoints (T1 - T3) and include rs-fNIRS/EEG and clinical pain measures. Cohort 2:
Participants with effective implanted SCS 6 months will participate in three study visits
conducted 24-48 hours apart. Data will be collected during SCS use and following an SCS
washout period. Data collection will be consistent across all data collection
timepoints(T1-T4) and include rs-fNIRS/EEG and clinical pain measures. Both cohorts will
receive paresthesia based SCS. AIM 1 is to characterize neurophysiological (rs-fNIRS/EEG)
brain signature of pain relief during the SCS trial period for patients with chronic
neuropathic pain who are na�ve to SCS. AIM 2 is to characterize neurophysiological
(rs-fNIRS/EEG) brain signature of pain relief in patients with chronic neuropathic pain
who have utilized SCS for 6 months. Outcome Measures to address both aims include
rs-functional connectivity (rs-fNIRS/EEG); and a composite clinical pain assessment that
will include Numeric Pain Rating Scale (NPRS), Patient Reported Outcomes Measurement
Information System-29 profile v2.1(PROMIS-29); EQ-5D-5L; Patient Global Impression of
Change (PGIC); painDetect; and activity monitoring. Significance: Studying changes in
brain connectivity in response to SCS will provide insight into the treatment mechanism
of SCS. Use of neuroimaging methods such as rs-fNIRS/EEG that can be easily applied in
the clinical setting to further refine patient selection for SCS may improve outcome in
SCS therapy. This grant will provide preliminary data for future studies aimed at
developing biomarkers of pain-relief with SCS treatment.