Sacral nerve stimulation increases activation of the primary somatosensory cortex by anal canal stimulation in an experimental model

• Published in: British journal of surgery Vol. 98; no. 8; pp. 1160 - 1169
• Main Authors: Griffin, K. M., Pickering, M., O'Herlihy, C., O'Connell, P. R., Jones, J. F. X.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.08.2011; Wiley
• Subjects: Anal Canal - physiology; Animals; Biological and medical sciences; Electric Stimulation; Electric Stimulation Therapy; Evoked Potentials, Somatosensory - physiology; Fecal Incontinence - therapy; Female; General aspects; Lumbosacral Plexus - physiology; Medical sciences; Neural Conduction - physiology; Rats; Rats, Wistar; Somatosensory Cortex - physiology; Medicine; Treatment; Surgery; Primary; Stimulation; Activation; Increase; Models; Experimental study; Sacral nerve; Anal canal
• ISSN: 0007-1323; 1365-2168
• DOI: 10.1002/bjs.7536

Background: Sacral and posterior tibial nerve stimulation may be used to treat faecal incontinence; however, the mechanism of action is unknown. The aim of this study was to establish whether sensory activation of the cerebral cortex by anal canal stimulation was increased by peripheral neuromodulation. Methods: A multielectrode array was positioned over the right primary somatosensory cortex of anaesthetized rats. A brief burst of electrical stimulation was applied to either the left sacral root or the left posterior tibial nerve, and evoked potentials from anal canal stimulation were signal‐averaged at intervals over 1 h. At the end of the experiment, the cerebral cortex was removed and probed for polysialylated neural cell adhesion molecule (PSA‐NCAM). Results: Sacral nerve root and posterior tibial nerve stimulation significantly increased the peak amplitude of primary cortical evoked potentials by 54·0 and 45·1 per cent respectively. This change persisted throughout the period of observation. The density of PSA‐NCAM‐positive cells in the somatosensory cortex underlying the electrode array was increased by approximately 50 per cent in the sacral nerve‐stimulated group. Conclusion: Brief sacral neuromodulation induces profound changes in anal canal representation on the primary somatosensory cortex, providing a plausible hypothesis concerning the mechanism of action of neuromodulation in the treatment of faecal incontinence. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. SNS effect on cortex mediated via anal canal