Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641626
Title: The effect of spinal cord injury on the motor function of the human colon, and the assessment of the influence of implanted radiofrequency stimulating electrodes
Author: Binnie, N. R.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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Abstract:
The control of bowel function in spinal cord injury is the principal problem examined in this thesis. After a preliminary review of the relevant anatomy and physiology, the accepted methods for the study of distal bowel function and of the pelvic floor are reviewed. A new anal plug electrode with longitudinal alignment of the electrode plates has been designed for surface acquistion of external anal sphincter EMG activity. This electrode is compared to an old electrode with circumferential electrode plates and is found to be significnatly more sensitive in detecting external anal sphincter EMG activity during standard electrophysiological investigations such as the pudendo-anal reflex latency test. The new electrode is also compared to invasive fine wire electrodes and shows a significant direct correlation at rest, squeeze and strain activities thus validating use of the new electrode in the detection of anismus. A study of paraplegics with and without neurogenic bowel stimulation by the Brindley stimulator compared with controls confirms a slow transit type of constipation with prolonged colonic transit time, reduced frequency of defaecation and reduced faecal water content. The Brindley S234 anterior sacral nerve root stimulator reduces the colonic transit time and increases the frequency of defaecation but is paradoxically associated with a further decrease in faecal water content. Stimulation of the S234 anterior roots results in increased peak wave height and colonic motility index above basal activity in all areas from the transverse colon to the rectum. The area most responsive to stimulation is the splenic flexure and S3 anterior root stimulation. The position of the pelvic floor and pressure generated by the external anal sphincter are maximally elevated by S43 anterior root stimulation. The maximum pressure produced by the external anal sphincter during S4 stimulation shows significant direct correlation with the duration of the implant and is in keeping with hypertrophy of the sphincter. The drug cisapride reduces the oro-anal gastrointestinal transit time in paraplegic subjects by significantly reducing the colonic transit time. The drug also increases the frequency of defaecation and intestinal mixing of transit markers. A non-invasive dorsal genital nerve stimulator was then designed to activate the external anal sphincter for the control of continence via a train of stimulations of the pudendo-anal reflex. The stimulator is shown to produce a significant rise in external anal sphincter pressure and EMG activity. An eight week course of repeated stimulation with this device is shown to return continence to a group of women with neurogenic faecal incontinence who have an intact pudendo-anal reflex. Finally the problem of intractable constipation with inappropriate contraction of the external anal sphincter during straining at defaecation, anismus, is shown to be amenable to correction by a course of electrical biofeedback training using a portable EMG device with a new type of anal-plug electrode. In a final discussion, neural control is seen as a means whereby it is possible to manipulate neurogenic and reflex distal bowel activity in paraplegic man and in others with incontinence and severe chronic constipation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.641626  DOI: Not available
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