title: Comparison of burst and tonic spinal cord stimulation on spinal neural processing in an animal model.
abstract: OBJECTIVE
  Spinal cord stimulation (SCS) using bursts of pulses suppressed neuropathic pain as well or better than tonic stimulation and limited the incidences of parasthesias. The present translational study explored possible differences in mechanisms of burst and tonic SCS on nociceptive spinal networks and/or the gracile nucleus supraspinal relay.
  
  
  METHODS
  Visceromotor reflexes (VMRs, a nociceptive response) or extracellular activity of either L6-S2 spinal neurons or gracile nucleus neurons were recorded during noxious somatic stimulation (pinching) and visceral stimulation (colorectal distension [CRD]) in anesthetized rats. A stimulating (unipolar, ball) electrode at L2-L3 delivered 40 Hz burst or tonic SCS at different intensities relative to motor threshold (MT).
  
  
  RESULTS
  Average MTs for burst SCS were significantly lower than for tonic SCS. Burst SCS reduced the VMR more than tonic SCS. After high-intensity SCS (90% MT), spinal neuronal responses to CRD and pinch were reduced similarly for burst and tonic SCS. At low-intensity SCS (60% MT), only burst SCS significantly decreased the nociceptive somatic response. Tonic but not burst SCS significantly increased spontaneous activity of neurons in the gracile nucleus.
  
  
  CONCLUSIONS
  Based on the clinically relevant burst versus tonic parameters used in this study, burst SCS is more efficacious than tonic SCS in attenuating visceral nociception. Burst and tonic SCS also suppress lumbosacral neuronal responses to noxious somatic and visceral stimuli; however, burst SCS has a greater inhibitory effect on the neuronal response to noxious somatic stimuli than to noxious visceral stimuli. Reduced or abolished paresthesia in patients may be due in part to burst SCS not increasing spontaneous activity of neurons in the gracile nucleus.
authors.affiliation: Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA; Department of Anesthesiology, The First Hospital of China Medical University, Shenyang, China.
authors.forename: Rurong
authors.initials: R
authors.lastname: Tang
authors.forename: Marte
authors.initials: M
authors.lastname: Martinez
authors.forename: Melanie
authors.initials: M
authors.lastname: Goodman-Keiser
authors.forename: Jay P
authors.initials: JP
authors.lastname: Farber
authors.forename: Chao
authors.initials: C
authors.lastname: Qin
authors.forename: Robert D
authors.initials: RD
authors.lastname: Foreman
mesh_terms: D000818:Animals; D008297:Male; D023421:Models, Animal; D010147:Pain Measurement / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D062187:Spinal Cord Stimulation / Q000379:methods*; D013127:Spinal Nerves / Q000502:physiology*; D059265:Visceral Pain / Q000503:physiopathology
keywords: Basic science; nociceptive pain; paresthesia; spinal cord stimulation; visceral pain