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Neural correlates of heterotopic facilitation induced after high frequency electrical stimulation of nociceptive pathways.

van den Broeke EN, van Heck CH, van Rijn CM, Wilder-Smith OH - Mol Pain (2011)

Bottom Line: Several studies suggest that this heterotopic effect is the result of central (spinal) plasticity.Two different cortical correlates were found; the first one was a lateralized effect, i.e. a larger N100 amplitude on the conditioned arm than the control arm 30 minutes after end of HFS.This was comparable with the observed lateralized effect of visual analogue scale (VAS) scores as response to the mechanical punctate stimuli.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Pain & Palliative Medicine, Pain & Nociception Neuroscience Research Group, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. E.vandenbroeke@anes.umcn.nl

ABSTRACT

Background: High frequency electrical stimulation (HFS) of primary nociceptive afferents in humans induce a heightened sensitivity in the surrounding non-stimulated skin area. Several studies suggest that this heterotopic effect is the result of central (spinal) plasticity. The aim of this study is to investigate HFS-induced central plasticity of sensory processing at the level of the brain using the electroencephalogram (EEG). To this end we measured evoked potentials in response to noxious electrical pinprick-like stimuli applied in the heterotopic skin area before, directly after and 30 minutes after HFS.

Results: We observed potential cortical electrophysiological correlates of heterotopic facilitation. Two different cortical correlates were found; the first one was a lateralized effect, i.e. a larger N100 amplitude on the conditioned arm than the control arm 30 minutes after end of HFS. This was comparable with the observed lateralized effect of visual analogue scale (VAS) scores as response to the mechanical punctate stimuli. The second correlate seems to be a more general (non-lateralized) effect, because the result affects both arms. On average for both arms the P200 amplitude increased significantly 30 minutes after end of HFS with respect to baseline.

Conclusions: We suggest that for studying heterotopic nociceptive facilitation the evoked brain response is suitable and relevant for investigating plasticity at the level of the brain and is perhaps a more sensitive and reliable marker than the perceived pain intensity (e.g. VAS).

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Behavioral measurements. A) Mean (and SEM) VAS-scores as response to mechanical punctate test stimulation. The VAS-score observed at the conditioned arm was significantly higher than the VAS-score observed at the control arm 30 minutes after experimental conditioning stimulation (post (2)) * = p < .05. B) Mean (and SEM) VAS-scores as response to electrical pinprick-like test stimulation. Averaged for both arms a significant decrease of the VAS-score was present between baseline (pre) and post (1) experimental conditioning stimulation * = p < .05.
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Figure 3: Behavioral measurements. A) Mean (and SEM) VAS-scores as response to mechanical punctate test stimulation. The VAS-score observed at the conditioned arm was significantly higher than the VAS-score observed at the control arm 30 minutes after experimental conditioning stimulation (post (2)) * = p < .05. B) Mean (and SEM) VAS-scores as response to electrical pinprick-like test stimulation. Averaged for both arms a significant decrease of the VAS-score was present between baseline (pre) and post (1) experimental conditioning stimulation * = p < .05.

Mentions: More interestingly a significant Time × Arm interaction effect (F (2,16) = 3.952, p = .040, eta2 = .331) was found. The univariate within-subject contrasts showed a statistically significant difference in VAS-score on post2 (versus pre) between the two arms (conditioned vs. control arm) (F (1,17) = 8.331, p = .010, eta2 = .329). The VAS-score observed at the conditioned arm was significantly higher (M = 3.1) than the VAS-score observed at the control arm (M = 2.1) 30 minutes after experimental conditioning stimulation (figure 3A).


Neural correlates of heterotopic facilitation induced after high frequency electrical stimulation of nociceptive pathways.

van den Broeke EN, van Heck CH, van Rijn CM, Wilder-Smith OH - Mol Pain (2011)

Behavioral measurements. A) Mean (and SEM) VAS-scores as response to mechanical punctate test stimulation. The VAS-score observed at the conditioned arm was significantly higher than the VAS-score observed at the control arm 30 minutes after experimental conditioning stimulation (post (2)) * = p < .05. B) Mean (and SEM) VAS-scores as response to electrical pinprick-like test stimulation. Averaged for both arms a significant decrease of the VAS-score was present between baseline (pre) and post (1) experimental conditioning stimulation * = p < .05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108312&req=5

Figure 3: Behavioral measurements. A) Mean (and SEM) VAS-scores as response to mechanical punctate test stimulation. The VAS-score observed at the conditioned arm was significantly higher than the VAS-score observed at the control arm 30 minutes after experimental conditioning stimulation (post (2)) * = p < .05. B) Mean (and SEM) VAS-scores as response to electrical pinprick-like test stimulation. Averaged for both arms a significant decrease of the VAS-score was present between baseline (pre) and post (1) experimental conditioning stimulation * = p < .05.
Mentions: More interestingly a significant Time × Arm interaction effect (F (2,16) = 3.952, p = .040, eta2 = .331) was found. The univariate within-subject contrasts showed a statistically significant difference in VAS-score on post2 (versus pre) between the two arms (conditioned vs. control arm) (F (1,17) = 8.331, p = .010, eta2 = .329). The VAS-score observed at the conditioned arm was significantly higher (M = 3.1) than the VAS-score observed at the control arm (M = 2.1) 30 minutes after experimental conditioning stimulation (figure 3A).

Bottom Line: Several studies suggest that this heterotopic effect is the result of central (spinal) plasticity.Two different cortical correlates were found; the first one was a lateralized effect, i.e. a larger N100 amplitude on the conditioned arm than the control arm 30 minutes after end of HFS.This was comparable with the observed lateralized effect of visual analogue scale (VAS) scores as response to the mechanical punctate stimuli.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Pain & Palliative Medicine, Pain & Nociception Neuroscience Research Group, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. E.vandenbroeke@anes.umcn.nl

ABSTRACT

Background: High frequency electrical stimulation (HFS) of primary nociceptive afferents in humans induce a heightened sensitivity in the surrounding non-stimulated skin area. Several studies suggest that this heterotopic effect is the result of central (spinal) plasticity. The aim of this study is to investigate HFS-induced central plasticity of sensory processing at the level of the brain using the electroencephalogram (EEG). To this end we measured evoked potentials in response to noxious electrical pinprick-like stimuli applied in the heterotopic skin area before, directly after and 30 minutes after HFS.

Results: We observed potential cortical electrophysiological correlates of heterotopic facilitation. Two different cortical correlates were found; the first one was a lateralized effect, i.e. a larger N100 amplitude on the conditioned arm than the control arm 30 minutes after end of HFS. This was comparable with the observed lateralized effect of visual analogue scale (VAS) scores as response to the mechanical punctate stimuli. The second correlate seems to be a more general (non-lateralized) effect, because the result affects both arms. On average for both arms the P200 amplitude increased significantly 30 minutes after end of HFS with respect to baseline.

Conclusions: We suggest that for studying heterotopic nociceptive facilitation the evoked brain response is suitable and relevant for investigating plasticity at the level of the brain and is perhaps a more sensitive and reliable marker than the perceived pain intensity (e.g. VAS).

Show MeSH
Related in: MedlinePlus