Biomedical subjects
N J Kenefick
Publications and source records attributed to N J Kenefick.
A review of sacral nerve stimulation for the treatment of faecal incontinence.
Sacral nerve stimulation is an emerging surgical technique that uses chronic low-level electrical stimulation, applied to the nerves of the sacral plexus, to produce a clinically beneficial physiological effect on the lower bowel, pelvic floor and anal canal. Faecal incontinence is common, maximal conservative therapy may improve some patients but many require surgery. Results are variable and often unsatisfactory and further options are limited, the traditional end-point being the formation of a colostomy. Sacral nerve stimulation appears to be an alternative treatment that is successful, has low morbidity, is maintained in the medium term and associated with an improved quality of life. The technique has the advantage of a minimally invasive test procedure with high predictive value and the surgery is minor. The underlying mechanism of action although predominately neurological in nature remains to be determined. Precise patient selection is currently unclear however, results are superior to other techniques.
Effect of sacral nerve stimulation on autonomic nerve function.
BACKGROUND: Sacral nerve stimulation has been used successfully to treat motility disorders of the bladder and bowel. The mechanism of action remains unknown. This study examined the effect of stimulation on rectal blood flow as a measure of autonomic nerve function. METHODS: Sixteen patients (15 women) of median age 59 (range 38-71) years were studied. All had undergone permanent electrode implantation for faecal incontinence, a median of 27 (range 2-62) months previously, with clinical benefit. Rectal laser Doppler flowmetry was performed at the level of chronic stimulation, without stimulation, and then at 0.1-V stepwise increments between zero and 1.0 V, and at 1-V increments to 5 V. RESULTS: There was a significant difference in the median flux between no stimulation and chronic stimulation: 545 (range 355-887) versus 869 (range 507-989) flux units (P = 0.001). Stepwise increments of 0.1 V, between zero and 1.0 V, caused a significant immediate rise in flux (P < 0.001). Further increments did not result in any further significant increase. CONCLUSION: Chronic sacral nerve stimulation has a significant effect on rectal blood flow and the autonomic innervation of the distal bowel. The response is rapidly reversible and varies in a dose-dependent manner up to a level of stimulation of 1.0 V.
Medium-term results of permanent sacral nerve stimulation for faecal incontinence.
BACKGROUND: Anal sphincter surgery for faecal incontinence is associated with significant morbidity and a variable outcome. Sacral nerve stimulation may provide a good functional outcome with minimal morbidity. This paper reports the experience in a single centre over 5 years. METHODS: Fifteen consecutive patients (14 women), median age 60 (range 37-71) years, underwent temporary, and subsequent permanent, stimulation. All had incontinence to solid or liquid stool; the aetiology was obstetric injury (seven patients), scleroderma (four), idiopathic (two), fistula surgery (one) and repaired rectal prolapse (one). Median duration of symptoms was 6 (range 2-15) years. Clinical evaluation, endoanal ultrasonography, bowel diary, quality of life questionnaire (Short Form (SF) 36) and anorectal physiological testing were performed before and after stimulation. RESULTS: Continence had improved in all patients at median follow-up of 24 (range 3-60) months. Eleven patients were fully continent. Episodes of faecal incontinence decreased from median (range) 11 (2-30) per week before stimulation to 0 (0-4) per week after permanent stimulation (P < 0.001). Urgency improved in all patients (median (range) ability to defer less than 1 (0-1) versus 8 (1-15) min; P = 0.01). 'Social function' and 'role-physical' subscales of the SF36 improved significantly. Mean resting pressure (35 versus 49 cmH2O with temporary stimulation; P < 0.05) and squeeze pressure increment (43 versus 69 cmH2O with permanent stimulation; P < 0.01) increased. Rectal sensitivity to initial distension changed (mean 47 versus 34 ml air; P < 0.05). There were no major complications. CONCLUSION: Sacral nerve stimulation is a safe and effective treatment for faecal incontinence when conventional treatment has failed. There is minimal morbidity. The benefit is maintained in the medium term.
Permanent sacral nerve stimulation for treatment of idiopathic constipation.
BACKGROUND: Constipation can usually be managed using conservative therapies. A proportion of patients require more intensive treatment. Surgery provides variable results. This paper describes an alternative approach, in which the neural control of the bowel and pelvic floor is modified, using permanent sacral nerve stimulation. METHODS: Four women (aged 27-36 years), underwent temporary and then permanent stimulation. All had idiopathic constipation, resistant to maximal therapy, with symptoms for 8-32 years. Clinical evaluation, bowel diary, Wexner constipation score, symptom analogue score, quality of life questionnaire and anorectal physiology were completed. RESULTS: There was a marked improvement in all patients with temporary, and in three with permanent, stimulation. Median follow-up was 8 (range 1-11) months. Bowel frequency increased from 1-6 to 6-28 evacuations per 3 weeks. Improvement occurred, at longest-follow-up, in median (range) evacuation score (4 (0-4) versus 1 (0-4)), time with abdominal pain (98 (95-100) versus 12 (0-100) per cent), time with bloating (100 (95-100) versus 12 (5-100) per cent), Wexner score (21 (20-22) versus 9 (1-20)), analogue score (22 (16-32) versus 80 (20-98)) and quality of life. Maximum anal resting and squeeze pressures increased. Rectal sensation was altered. Transit time normalized in one patient. CONCLUSION: Permanent sacral nerve stimulation can be used to treat patients with resistant idiopathic constipation.
Double-blind placebo-controlled crossover study of sacral nerve stimulation for idiopathic constipation.
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Treatment of resistant anal fissure with advancement anoplasty.
OBJECTIVE: The primary aim of this study was to assess the outcome of advancement anoplasty in the treatment of chronic anal fissure, resistant to conventional therapy. The secondary aim was to evaluate the anal resting pressure in these patients with resistant fissures. PATIENTS AND METHODS: Over a five-year period eight patients (2 male, median age 55 years, range 20-74) with resistant anal fissure were referred from 6 centres. They had endured symptoms for a median of 8 years (range 2-20) and had undergone a median of 2 previous surgical procedures (range 1-3), including lateral sphincterotomy and anal dilatation. Anorectal physiological testing was performed on all patients who then underwent advancement anoplasty. The outcome was analysed retrospectively. RESULTS: Pre-operative anorectal physiological testing showed a significantly lowered median maximal anal resting pressure of 42 mm H2O (range 12-72 mm H2O, normal range > 60 mm), P=0.03. All patients underwent advancement anoplasty. At a median of seven months follow-up (range 2-22) seven of eight patients had healed their fissure and were asymptomatic. The median healing time was four months (range 2-6). CONCLUSION: Patients with chronic anal fissure, resistant to conventional therapy, may be successfully treated by advancement anoplasty. Healing time however, may be prolonged. In this series patients had a decreased anal resting pressure rather than anal hypertonia.
Injectable silicone biomaterial for faecal incontinence due to internal anal sphincter dysfunction.
BACKGROUND: A weak or disrupted internal anal sphincter can cause passive faecal incontinence. Conservative measures may help some patients but there is no simple surgical solution for those who fail conservative treatment. A successful technique using trans-sphincteric injection of a bulking agent to augment the internal anal sphincter was developed in a previous pilot study. AIM: To determine the clinical results and underlying physiological effects of biomaterial injection. PATIENTS: Six patients (four males, median age 53 years (range 36-65)) with faecal incontinence to solid or liquid stool related to poor internal anal sphincter function, of varied aetiology, were recruited. METHODS: Silicone based biomaterial injections were performed, under local anaesthesia, with antibiotic cover. Three injections were placed circumferentially, trans-sphincterically, entering away from the anal margin and injecting at or just above the dentate line. Anorectal physiological studies, endoanal ultrasound, a bowel symptom diary, a validated incontinence score, and quality of life questionnaires were completed before treatment and on completion of follow up. RESULTS: At a median follow up of 18 months (range 15-19), five of six patients had marked symptom improvement. Faecal incontinence scores improved from a median of 14/24 (range 11-20) before to 8/24 (6-15) after injection. Short form-36 quality of life physical and social function scores improved from a median of 26/100 (5-33) to 79/100 (25-100) and from 10/100 (5-37) to 100/100 (50-100), respectively. There was a corresponding physiological increase in maximum anal resting and squeeze pressures. Ultrasound showed the Bioplastique to be retained in the correct position in the improved patients without migration. There were no complications. CONCLUSION: Trans-sphincteric injection of silicone biomaterial can provide a marked improvement in faecal incontinence related to a weak or disrupted internal anal sphincter. This is associated with improved sphincter function and quality of life.
Sacral nerve stimulation for faecal incontinence due to systemic sclerosis.
BACKGROUND: Faecal incontinence occurs in over one third of patients with systemic sclerosis. The aetiology is multifactorial. Conventional treatment is often unsuccessful. Sacral nerve stimulation is a new effective treatment for resistant faecal incontinence. AIMS: To evaluate sacral nerve stimulation in patients with systemic sclerosis. PATIENTS: Five women, median age 61 years (30-71), with scleroderma associated faecal incontinence were evaluated. All had failed maximal conventional treatment. Median number of preoperative weekly episodes of incontinence was 15 (7-25), median duration of incontinence was five years (5-9), and scleroderma 13 years (4-29). METHODS: All patients were screened with temporary stimulation. Those who benefited underwent permanent implantation. At baseline and after stimulation a bowel diary, the SF-36 quality of life assessment, endoanal ultrasound, and anorectal physiology were performed. RESULTS: Four patients were continent at a median follow up of 24 months (6-60). One patient failed temporary stimulation and was not permanently implanted. The weekly episodes of incontinence decreased from 15, 11, 23, and 7 to 0. Urgency resolved (median time to defer <1 minute (0-1) v 12.5 minutes (5-15)). Quality of life, especially social function, improved. Endoanal ultrasound showed an atrophic internal anal sphincter (median width 1.0 mm (0-1.6)). Anorectal physiology showed an increase in median resting pressure (37 pre v 65 cm H(2)O post) and squeeze pressure (89 v 105 cm H(2)O). Stimulation produced enhanced rectal sensitivity to distension. There were no major complications. CONCLUSIONS: Sacral nerve stimulation is a safe and effective treatment for resistant faecal incontinence secondary to scleroderma. The benefit is maintained in the medium term.
Non-surgical management of faecal incontinence.
Faecal incontinence is a common symptom causing reduction in quality of life and social isolation. Conservative treatments should be used as first and second lines of therapy and can also be of use as adjuncts to surgical treatment. This article reviews the current status of these modalities of treatment.
Factors predictive of outcome after surgery for faecal incontinence.
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