Repetitive transcranial magnetic stimulation over primary motor vs non-motor cortical targets; effects on experimental hyperalgesia in healthy subjectsReportar como inadecuado




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BMC Neurology

, 14:166

Neuromuscular disorders and peripheral neurology

Abstract

BackgroundHigh frequency repetitive transcranial magnetic stimulation rTMS targetted to different cortical regions primary motor-sensory, prefrontal are known to alter somatosensory responses. The mechanisms for these effects are unclear. We compared the analgesic effects of rTMS at different cortical sites on hyperalgesia induced using topical capsaicin cream.

MethodsFourteen healthy subjects had capsaicin cream applied to a 16 cm area of the medial aspect of the right wrist 60 min on 4 separate occasions over 6 weeks. rTMS 10Hz for 10s-min = 2000 stimuli @ 90% resting motor threshold of first dorsal interosseus muscle was applied to the optimum site for right hand M1, left dorsolateral prefrontal DLFPC and occipital midline OCC in a pseudo-randomised order. Thermal and mechanical perception and pain thresholds were determined using standardised quantitative sensory testing QST methods at the capsaicin site. Subjective responses to thermal stimuli pain score on a numerical rating scale from −2.5°C to +2.5°C of the individualised heat pain threshold HPT resulted in a hyperalgesia curve. Sensory testing took place prior to capsaicin application PRE-CAP, after 30 min of capsaicin POST-CAP and following rTMS 30 min = POST-TMS.

ResultsCapsaicin application resulted in substantial changes in thermal but not mechanical sensitivity to both heat and cold eg. HPT PRE-CAP = 43.6°C to POST-CAP = 36.7°C p < 0.001 with no differences between groups pre-rTMS. POST-TMS HPT showed no changes for any of the treatment groups, however the pain scores for the hyperalgesia curve were significantly lower for M1 vs OCC −24.7%, p < 0.001 and for M1 vs DLFPC −18.3%, p < 0.02.

ConclusionrTMS over the primary motor cortex results in a significant analgesic effect compared to other cortical areas.

KeywordsExperimental pain Capsaicin Repetitive TMS Electronic supplementary materialThe online version of this article doi:10.1186-s12883-014-0166-3 contains supplementary material, which is available to authorized users.

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Autor: Paul Sacco - Michael Prior - Helen Poole - Turo Nurmikko

Fuente: https://link.springer.com/







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