title: Brain activity modifications following spinal cord stimulation for chronic neuropathic pain: A systematic review.
abstract: OBJECTIVE
  Spinal cord stimulation (SCS) is believed to exert supraspinal effects; however, these mechanisms are still far from fully elucidated. This systematic review aims to assess existing neurophysiological and functional neuroimaging literature to reveal current knowledge regarding the effects of SCS for chronic neuropathic pain on brain activity, to identify gaps in knowledge, and to suggest directions for future research.
  
  
  METHODS
  Electronic databases and hand-search of reference lists were employed to identify publications investigating brain activity associated with SCS in patients with chronic neuropathic pain, using neurophysiological and functional neuroimaging techniques (fMRI, PET, MEG, EEG). Studies investigating patients with SCS for chronic neuropathic pain and studying brain activity related to SCS were included. Demographic data (age, gender), study factors (imaging modality, patient diagnoses, pain area, duration of SCS at recording, stimulus used) and brain areas activated were extracted from the included studies.
  
  
  RESULTS
  Twenty-four studies were included. Thirteen studies used neuroelectrical imaging techniques, eight studies used haemodynamic imaging techniques, two studies employed both neuroelectrical and haemodynamic techniques separately, and one study investigated cerebral neurobiology.
  
  
  CONCLUSIONS
  The limited available evidence regarding supraspinal mechanisms of SCS does not allow us to develop any conclusive theories. However, the studies included appear to show an inhibitory effect of SCS on somatosensory evoked potentials, as well as identifying the thalamus and anterior cingulate cortex as potential mediators of the pain experience. The lack of substantial evidence in this area highlights the need for large-scale controlled studies of this kind.
authors.affiliation: Faculty of Health, Education & Life Sciences, Birmingham City University, UK.
authors.forename: L D
authors.initials: LD
authors.lastname: Bentley
authors.affiliation: Department of Public Health, Epidemiology and Biostatistics, University of Birmingham, UK.
authors.forename: R V
authors.initials: RV
authors.lastname: Duarte
authors.affiliation: Aston Brain Centre, Aston University, Birmingham, UK.
authors.forename: P L
authors.initials: PL
authors.lastname: Furlong
authors.affiliation: Faculty of Health, Education & Life Sciences, Birmingham City University, UK.
authors.forename: R L
authors.initials: RL
authors.lastname: Ashford
authors.affiliation: Faculty of Health, Education & Life Sciences, Birmingham City University, UK.|Department of Pain Management, Russells Hall Hospital, Dudley Group of Hospitals NHS Trust, UK.
authors.forename: J H
authors.initials: JH
authors.lastname: Raphael
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D059350:Chronic Pain / Q000503:physiopathology* / Q000628:therapy*; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000503:physiopathology* / Q000628:therapy*; D062187:Spinal Cord Stimulation