Colonosphincteric electromyographic responses to sacral root stimulation: evidence for a somatosympathetic reflex.
The aim of the present study was to determine the effects of selectively stimulating the afferent fibres running in the dorsal sacral roots (S1, S2, S3) and the somatic (radial and sciatic) nerves on colonic and internal anal sphincter (IAS) electromyographic (EMG) activity in anaesthetized cats to try to understand how sacral nerve stimulation can improve fecal continence in human. Electrically stimulating the afferent fibres present in the sacral dorsal roots and somatic nerves inhibited the colonic spike potential frequency (n = 97) and increased the slow variations in the sphincteric membrane potential (n = 76). These effects were found to have disappeared after administering an alpha-noradrenergic receptor blocker (n = 64) or sectioning the sympathetic efferent fibres innervating these organs (n = 69) suggesting the involvement of the sympathetic system in the effects observed. Moreover, no significant differences were observed between the effects of sacral dorsal root vs somatic nerve stimulation on colonic and sphincteric EMG activity. In conclusion, the data obtained here show that neurostimulation applied to the sacral spinal roots may improve fecal continence by inhibiting colonic activity and enhancing IAS activity via a somatosympathetic reflex.
Laboratoire de Physiologie Neurovégétative, (UMR 6153 CNRS/UMR 1147 INRA/Université Paul Cézanne-Aix-Marseille III), Service d'Hépato-Gastro-Entérologie, CHU Nord, Marseille, France.
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Vitton
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Abysique
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Gaigé
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Leroi
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Bouvier
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D001003:Anal Canal / Q000294:innervation / Q000502:physiology*; D000818:Animals; D019771:Axotomy; D002415:Cats; D003106:Colon / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D003672:Defecation / Q000502:physiology; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy; D005242:Fecal Incontinence / Q000503:physiopathology; D005260:Female; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D010646:Phentolamine / Q000494:pharmacology; D012018:Reflex; D012445:Sacrococcygeal Region; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D010646:Phentolamine