N. R. Binnie

Outlet obstruction constipation (anismus) managed by biofeedback.

Fifteen subjects presenting with intractable constipation due to obstructive defecation, mean (SEM) duration 8.8 (1.8) years, had the inappropriate contraction and electromyographic changes in the pelvic floor muscles and external and sphincter typical of this condition. An electromyographically derived index was used to grade its severity. A self applied biofeedback device was used to allow electromyographic recording of the abnormal external anal sphincter. The subjects were encouraged to reduce the abnormal electromyographic activity on straining after instruction and training. The procedure was intended as a relearning process in which the non-relaxing activity of the pelvic floor was gradually suppressed. Biofeedback training was maintained on a domiciliary basis for a mean time of 3.1 weeks and resulted in a significant reduction in the anismus index (mean (SEM) 69.9 (7.8)% before biofeedback, mean 14 (3.9)% after biofeedback, p less than 0.01). There was an associated reduction in the time spent straining at stool and in the difficulty of defecation and an increased frequency of defecation. Defecatory video proctograms in six subjects showed improvements in the anorectal angle during straining and evacuation. The clinical benefit to the patients persisted after a mean follow up of 6.2 months.

Constipation associated with chronic spinal cord injury: the effect of pelvic parasympathetic stimulation by the Brindley stimulator

Ten subjects with severe constipation due to complete spinal cord injury (SCI) had prolonged oro-anal transit time (p<0.01), diminished faecal water content (p<0.05) and a reduced frequency of defaecation (p<0.01) compared to 10 non-SCI subjects. Paraplegics with an implanted Brindley S234 anterior sacral nerve root stimulator had a significant increase in frequency of defaecation (p<0.01), compared to the SCI group while the faecal water content was less although not significantly so. The Brindley stimulator group also showed a more rapid colonic transit than the SCI group but this did not reach statistical significance. SCI is associated with constipation which therefore appears to be favourably influenced by the Brindley S234 anterior nerve root stimulator. The effects produced are compatible with stimulation of left colonic motility, which facilitates the emptying of the distal colon, but also suggest that part of the response restricts transit in some areas of the colon or rectum. Since the motility changes induced by the Brindley stimulator do not affect the right colon a relatively greater residence time of the faecal bolus in this part of the large bowel would enhance water absorption.

The action of Cisapride on the chronic constipation of paraplegia

Paraplegic patients have intractable constipation associated with prolonged colonic transit time. The agent Cisapride significantly reduced the colonic transit time from 7.7 days to 5.1 days. It also improved the intraluminal tone in the rectum, resulting in a significant reduction in maximal rectal capacity from 305.8 ml to 224.3 ml. There was a reduction in residual urine volume from 51.5 ml to 27.7 ml. The increased number of stools containing transit markers showed that intraluminal mixing was increased by cisapride. Faecal water remained unchanged. A side effect was retention of urine in one subject after sudden withdrawal of the drug but this was avoided by its gradual reduction over 2 days.

Use of the pudendo-anal reflex in the treatment of neurogenic faecal incontinence.

An electrical stimulator has been devised to treat neurogenic faecal incontinence caused by pudendal nerve neuropathy and works on the basis of repeated stimulation of the pudendo-anal reflex arc. Although conduction in the pudendo-anal reflex arc may be prolonged, and is so in neurogenic faecal incontinence, it must be shown to be present before the method can be used. This stimulation results in an immediate rise in the pressure in the anal canal and a significant increase in the electromyographic activity of the external anal sphincter. Maintenance of the stimulus over a two month period raised the mean resting pressure significantly in the anal canal and increased the reflex and voluntary responses of the external anal sphincter to coughing and squeezing actions respectively. The length of the sphincter was not affected. There was widening of the mean motor unit potential duration, though this was not significant. The resting electromyogram was enhanced after the course of treatment, indicating greater spontaneous activity in the external sphincter. The changes led to seven of the eight patients studied becoming continent at the end of the treatment.

Motility Effects of Electrical Anterior Sacral Nerve Root Stimulation of the Parasympathetic Supply of the Left Colon and Anorectum in Paraplegic Subjects

The extent and nature of colonic and anorectal motility responses to S2, S3, and S4 anterior nerve root stimulation were studied in seven paraplegic patients with a Brindley electromicturition sacral implant. After sequential S2, S3 and S4 stimulation wave height activity was increased above basal from the transverse colon to the rectum. The mean motility index response to sequential stimulation was greatest at the splenic flexure. The greatest peak wave height and mean motility index response to individual anterior nerve root stimulation was to S3, which could empty the left colon by a distal motility gradient. S4 anterior root stimulation increased the intrarectal pressure and also raised the anal canal pressure to high levels.

Effect of Electrical Anterior Sacral Nerve Root Stimulation on Pelvic Floor Function in Paraplegic Subjects

The effect of the Brindley stimulator on pelvic floor function has been studied in seven paraplegic subjects by standard manometric, radiologic, and electrophysiologic methods. There was no difference in the maximum resting pressure in the anal canal between the stimulated group and paraplegic subjects without sacral stimulators acting as controls. The fall in pressure in response to the rectosphinteric reflex as a percentage of the original resting pressure was significantly less, indicating a proportional effect on the external sphincter. There was less descent of the pelvic floor at rest in the stimulated group, but no difference in the pudendoanal reflex latency, motor unit potential duration, or resting electromyogram activity of the external anal sphincter. The maximum resting pressure in the anal canal, the pudendoanal reflex response amplitude, and the external anal sphincter electromyogram activity increased, however, with the duration of the implant. The S4 root had the dominant effect on the pelvic floor, with decreasing effects from the S3 and S2 roots on the pressure and integrated electromyogram activity generated by the external anal sphincter. The anorectal angle had not changed at rest in the group with the stimulator, but S4 root stimulation made it more acute than S3 or S2 root stimulation. The results suggest profound effects of S4 anterior root stimulation on the pelvic floor with additional effects of S3 and S2 anterior roots on pelvic function.