Comparative analysis of occlusion methods for artificial sphincters

An artificial sphincter is a device that replaces the function of the biological sphincter by occluding the relative biological lumen. The investigation of occlusion methods for artificial sphincters is crucial for a reliable and effective design of such devices. The compression induced onto the tissue by a certain pressure depends on the biomechanical and physiological features of the lumen and on the specific occlusion method. A numerical model and an experimental evaluation are presented here to assess the efficiency of different occlusion methods. Numerical models of circumferential occlusion and clamping occlusion methods to simulate the compression of the biological lumen were developed. Results revealed a relationship between the efficiency of the occlusion method and the physiological condition of the lumen. With differences related to the testing setup, this relationship was also confirmed experimentally by conducting tests on biological simulators. We analyzed the occlusion method to adopt as the physiological pressure (ie, leakage pressure values) changed. In particular, we focused on the urinary incontinence, which is a dysfunction involving the external sphincter surrounding the urethra. In this scenario, we demonstrated that a clamping occlusion is an efficient method to compress the urethra, whose physiological pressures range between 4 and 12 kPa. The clamping occlusion method resulted up to 35% more efficient in terms of sealing pressure than the circumferential one for a closing pressure varying between 2.3 and 11.5 kPa.

Efficacy of Bilateral Transcutaneous Posterior Tibial Nerve Stimulation for Fecal Incontinence

CONTEXT

Posterior tibial nerve stimulation is a new second-line treatment for refractory fecal incontinence.

OBJECTIVE

To assess the efficacy of bilateral transcutaneous posterior tibial nerve stimulation (BTPTNS) for treatment of fecal incontinence in Japanese patients and its impact on quality of life.

DESIGN

A prospective observational-interventional study was conducted from May 2015 to June 2017 in patients with fecal incontinence in whom conservative treatment had failed. All patients received a 30-minute session of stimulation twice weekly for 6 consecutive weeks. Evaluation at baseline and at 6 weeks involved the Wexner score, Fecal Incontinence Quality of Life (FIQL) questionnaire, and anal manometry. Patients recorded episodes of incontinence in a weekly diary.

MAIN OUTCOME MEASURES

Reduction of 50% or greater in incontinence episodes, decreased Wexner score, and improved FIQL scores.

RESULTS

Twenty-two patients with a median age of 64.1 years (range, 26-81 years) and men:women ratio of 9:13 completed BTPTNS. Mean episodes of fecal incontinence were significantly reduced from 4.7 to 1.5 (p < 0.05). An improvement of 50% or better in episodes of fecal incontinence was achieved in 77.2% of patients. The median Wexner score significantly decreased from 10.2 to 6.9 (p < 0.05). The median FIQL score improved from 2.7 to 3.1 (p = 0.06), and significant improvement was seen in the embarrassment domain (2.2 vs 2.8, p < 0.05). Resting and squeezing anal pressures revealed no significant changes.

CONCLUSION

Our findings suggest that BTPTNS is safe and well tolerated and may improve symptoms of fecal incontinence. This technique offers an additional noninvasive, less expensive form of treatment.

Design and Evaluation of an Intelligent Artificial Anal Sphincter System Powered by an Adaptive Transcutaneous Energy Transfer System

Objectives

The aim of this study was to optimize an intelligent artificial anal sphincter system (AASS) II for patients with severe fecal incontinence.

Methods

Redesigning and integrating a pressure sensor into the sphincter prosthesis allows us to reduce the sensor volume and makes it suitable for a chronic, ambulatory application. Furthermore, a close-loop frequency control method was designed for the transcutaneous energy transfer system. Finally, a longer working time of the implanted device was obtained by the low-power design of the hardware and software. The new model was implanted in 2 dogs and studied for periods of up to 5 weeks.

Results

The output voltage induced on the load of 30 Ω, for a variation range in k of 0.12 ~ 0.42, was maintained at approximately 6.8 V with a frequency control range of the 270 ~ 320 kHz. The minimum and maximum output voltages of the pressure sensor were found to be 1.7 V and 2.34 V, respectively, which corresponded to a pressure range of 90 ~ 120 kPa with maximum change rate of approximately 3.7% caused by the temperature variations. Moreover, compared with AASS I, the low-power design resulting in 94% reduction in power consumption.

Conclusions

The efficacy of the device in achieving continence and sensing the need to defecate was assessed in an animal model. The technical concept and the design of the AASS II turned out to be capable of fulfilling the medical requirements.

Power flow control of TET system for a novel artificial anal sphincter system

This paper presents an adaptive transcutaneous energy transfer system (TETS) integrated with a novel elastic scaling artificial anal sphincter system (ES-AASS) for treating severe faecal incontinence (FI). The ES-AASS is based on a novel executive mechanism that uses a spring scalable structure to clamp the rectum. To deliver the correct amount of power (i.e. to match the load demand under variable coupling conditions or different operation stages of the implanted device) for internal battery charging and ensure safety for the human body, theoretical analysis was conducted as a control rule with respect to the relationship between the phase of driver signals and output voltage. An easy regulating procedure to stabilize output voltage with a phase shift controller is also presented. To validate the phase control rules, a prototype of the TETS was constructed and its performance was validated across the whole coupling coefficient range (0.09 ∼ 0.29) as well as load resistance (50 ∼ 120 Ω). The results show that the output voltage of the secondary side can be maintained at a constant 7 V with a phase regulation range of 78.7-178.2° and the proposed controller has reached a maximal end-to-end power efficiency of 74.2% at 1 W.

Current and emerging treatment options for fecal incontinence

Fecal incontinence (FI) is a multifactorial disorder that imposes considerable social and economic burdens. The aim of this article is to provide an overview of current and emerging treatment options for FI. A MEDLINE search was conducted for English-language articles related to FI prevalence, etiology, diagnosis, and treatment published from January 1, 1990 through June 1, 2013. The search was extended to unpublished trials on ClinicalTrials.gov and relevant publications cited in included articles. Conservative approaches, including dietary modifications, medications, muscle-strengthening exercises, and biofeedback, have been shown to provide short-term benefits. Transcutaneous electrical stimulation was considered ineffective in a randomized clinical trial. Unlike initial studies, sacral nerve stimulation has shown reasonable short-term effectiveness and some complications. Dynamic graciloplasty and artificial sphincter and bowel devices lack randomized controlled trials and have shown inconsistent results and high rates of explantation. Of injectable bulking agents, dextranomer microspheres in non-animal stabilized hyaluronic acid (NASHA Dx) has shown significant improvement in incontinence scores and frequency of incontinence episodes, with generally mild adverse effects. For the treatment of FI, conservative measures and biofeedback therapy are modestly effective. When conservative therapies are ineffective, invasive procedures, including sacral nerve stimulation, may be considered, but they are associated with complications and lack randomized, controlled trials. Bulking agents may be an appropriate alternative therapy to consider before more aggressive therapies in patients who fail conservative therapies.

Outcome of percutaneous tibial nerve stimulation (PTNS) for fecal incontinence: a prospective cohort study

OBJECTIVES

The aim of this study was to assess the long-term efficacy of percutaneous tibial nerve stimulation (PTNS) in fecal incontinence (FI).

BACKGROUND

There is extensive evidence regarding the efficacy of PTNS in urinary incontinence. Data on the efficacy of PTNS for FI are limited to a few small case series with relatively short-follow up.

METHODS

A prospective cohort of patients with FI was studied. Incontinence scores were measured using a validated questionnaire (Cleveland Clinic Florida-FI score) at specific time points: before treatment, after completion of a treatment course (12 PTNS sessions), and before the last maintenance ("top-up") therapy. Deferment time and average number of weekly incontinence episodes were also estimated from a prospective bowel dairy kept by the patient at these time points. Quality of life was assessed with the Rockwood Fecal Incontinence Quality of Life questionnaire.

RESULTS

A total of 150 patients were recruited to the study between January 2008 and June 2012. Analysis was performed on 115 patients who continued to receive PTNS after a median follow-up of 26 (range, 12-42) months. The baseline Cleveland Clinic Florida-FI score ±SD (12.0 ± 3.9) improved after 12 PTNS sessions (9.4 ± 4.6, P < 0.0001) and after "top-up" treatments (10.0 ± 4.3, P < 0.0001). The increase in the Cleveland Clinic Florida-FI score between the end of the 12th session and the last "top-up" therapy was also significant (P = 0.04). A similar pattern was seen for the deferment time and the quality of life scores. The median time between "top-up" sessions was 12 months (range, 1-40 months), significantly longer than the recommended interval of 6 months.

CONCLUSIONS

PTNS is a well-tolerated treatment with high acceptability in the majority of patients. It provides a sustained improvement in FI up to 42 months in a relatively noninvasive manner. The effect of PTNS diminishes with time and additional therapy sessions at 6 monthly intervals may result in greater improvements. PTNS ought to be considered as the first step in all patients with FI refractory to maximum conservative therapies.

What is the best option for failed sphincter repair?

AIM

This study aimed to evaluate the outcome of various procedures for patients with fecal incontinence following failed sphincteroplasty.

METHOD

Patients who underwent surgery for failed sphincteroplasty from January 2000 to June 2011 [corrected] were identified. They were assessed using the Fecal Incontinence Quality of Life (FIQoL) scale and the Cleveland Clinic Florida-Wexner Fecal Incontinence Score (CCFFIS).

RESULTS

Fifty-nine patients [97% females; median age 52 (25-81) years] were identified. They underwent either repeat sphincteroplasty (RS; n = 33), artificial bowel sphincter (ABS; n = 11) or sacral nerve stimulation (SNS; n = 15). The median follow-up was 31 (3-138) months. The RS group had a significantly wider external sphincter defect and had undergone fewer previous sphincteroplasties. The most common complication was infection. The incidence of complications was significantly higher after ABS (73%) compared with RS (24%) and SNS (33%) (P = 0.01). Seventeen (29%) patients required re-operation for complications or failure, with a lower rate in the RS group (P = 0.004). There was no difference in the rates of device removal after ABS or SNS. Ten (17%) patients underwent further surgery or re-implantation of the device with no difference between the groups. At follow-up, five (45%) ABS and 10 (67%) SNS patients retained a functioning device (P = 0.4). The mean postoperative CCFFIS decreased from 17.5 to 11.5 in the RS group, from 18.7 to 8.6 in the ABS group, and from 17.6 to 9.1 in the SNS group (P ≤ 0.02 for all). There were no differences in the improvement of CCFFIS or FIQoL scores among groups.

CONCLUSION

RS, ABS and SNS are associated with similar improvements in continence after failed sphincteroplasty. Due to increased complications and re-operation with ABS and SNS, RS may be the first step in managing these patients.

What's New in the Toolbox for Constipation and Fecal Incontinence?

Constipation and fecal incontinence (FI) are common complaints predominantly affecting the elderly and women. They are associated with significant morbidity and high healthcare costs. The causes are often multi-factorial and overlapping. With the advent of new technologies, we have a better understanding of their underlying pathophysiology which may involve disruption at any levels along the gut-brain-microbiota axis. Initial approach to management should always be the exclusion of secondary causes. Mild symptoms can be approached with conservative measures that may include dietary modifications, exercise, and medications. New prokinetics (e.g., prucalopride) and secretagogues (e.g., lubiprostone and linaclotide) are effective and safe in constipation. Biofeedback is the treatment of choice for dyssynergic defecation. Refractory constipation may respond to neuromodulation therapy with colectomy as the last resort especially for slow-transit constipation of neuropathic origin. Likewise, in refractory FI, less invasive approach can be tried first before progressing to more invasive surgical approach. Injectable bulking agents, sacral nerve stimulation, and SECCA procedure have modest efficacy but safe and less invasive. Surgery has equivocal efficacy but there are promising new techniques including dynamic graciloplasty, artificial bowel sphincter, and magnetic anal sphincter. Despite being challenging, there are no short of alternatives in our toolbox for the management of constipation and FI.

Outcomes associated with Interstim therapy for medically refractory fecal incontinence

BACKGROUND

Fecal incontinence is a common, socially debilitating disorder. Initial management involves dietary manipulation with bulking agents or antidiarrheal medications and pelvic floor biofeedback. For patients failing these modalities, traditional surgical approaches are morbid and of variable efficacy. Sacral nerve neuromodulation (Interstim, sacral nerve stimulation) was approved in May 2011 for management of medically refractory fecal incontinence. This report summarizes our experience with this treatment modality.

METHODS

A prospectively maintained database from a colorectal specialty practice was reviewed from December 2011 to June 2013. Patient demographics, incontinence etiology, and medical treatment regimens were reviewed. Outcomes for Interstim placement and surgical morbidity were reviewed.

RESULTS

A total of 330 patients were evaluated in the clinic for fecal incontinence during the study period. A total of 33 patients (10%) were offered Interstim therapy. The mean age was 63 (39 to 91) years, and 91% (30 of 33) were female. The etiology of the incontinence was obstetric (81%), rectal prolapse (11%), neurogenic (5%), and iatrogenic (3%). The entire group failed either supplemental fiber or antidiarrheal medications and 73% (24 of 33) failed pelvic floor biofeedback. The mean number of bowel accidents/2-week bowel diary before implant was 19 (9 to 52). After phase I implant, 88% (29 of 33) experienced a successful test phase and proceeded to phase II permanent implant. The mean number of bowel accidents/2-week diary postimplant was 3 (0 to 12). A trend toward less severe episodes of incontinence postimplant was observed. There were no complications associated with either the phase I or phase II implant. There were no phase II failures although 1 patient underwent device explant 9 months after phase II implant for chronic pain.

CONCLUSIONS

Sacral nerve neuromodulation (Interstim, sacral nerve stimulation) is an effective and efficacious tool for management of medically refractory fecal incontinence that offers a less morbid surgical approach to this problem. Interstim should be considered the first-line surgical approach for medically refractory fecal incontinence.

Internal anal sphincter augmentation and substitution

There is an increasing recognition of the importance of internal anal sphincter (IAS) dysfunction presenting as passive faecal incontinence. This problem may manifest after anal sphincterotomy or following the more minimally invasive operations for haemorrhoids, as well as with advancing age. Because of the poor results of IAS plication and the beneficial outcomes with peri-urethral bulking agents in urology, these materials have been developed for use in IAS dysfunction. This review outlines the basic purported mechanisms of action, defining the materials in clinical use, their methods of deployment, complications and reported outcomes. There is still much that is unknown concerning the ideal agent or the volume and the technique of deployment, which will only be answered by powerful, prospective, randomized, controlled trials. The specific role of autologous stem cells designed to regenerate the sphincters in cases of functional impairment or muscle loss is yet to be seen.

Feedback control of TET system with variable coupling coefficients for a novel artificial anal sphincter

For treating severe faecal incontinence, the authors developed an intelligent artificial anal sphincter system (AASS) equipped with a feedback sensor that utilized a transcutaneous energy transfer system (TETS). To deliver the correct amount of power (i.e. to match the load demand under variable coupling conditions caused by changes in positioning between the coils due to fitting and changes in posture), a regulating method to stabilize output voltage with a closed loop variable-frequency controller was developed in this paper. The method via which the voltage gain characteristics of a voltage-fed series-tuned TETS were derived is also described. The theoretical analysis was verified by the results of the experiment. A numerical analysis method was used as a control rule with respect to the relationship between operating frequency and output voltage. To validate the feedback control rules, a prototype of the TET charging system was constructed, and its performance was validated with the coupling variation between 0.12-0.42. The results show that the output voltage of the secondary side can be maintained at a constant 7 V across the whole coupling coefficient range, with a switching frequency regulation range of 271.4-320.5 kHz, and the proposed controller has reached a maximal end-to-end power efficiency of 67.5% at 1 W.

Anorectal incontinence: a challenge in diagnostic and therapeutic approach

Anorectal incontinence is a symptom of a complex multifactorial disorder involving the pelvic floor and anorectum, which is a severe disability and a major social problem. Various causes may affect the anatomical and functional integrity of the pelvic floor and anorectum, leading to the anorectal continence disorder and incontinence. The most common cause of anorectal incontinence is injury of the sphincter muscles following delivery or anorectal surgeries. Although the exact incidence of anorectal incontinence is unknown, various studies suggest that it affects ~2.2-8.3% of adults, with a significant prevalence in the elderly (>50%). The successful treatment of anorectal incontinence depends on the accurate diagnosis of its cause. This can be achieved by a thorough assessment of patients. The management of incontinent patients involves conservative therapeutic procedures, surgical techniques, and minimally invasive approaches.

Infection rates in a large investigational trial of sacral nerve stimulation for fecal incontinence

INTRODUCTION

Treatment options for patients with fecal incontinence (FI) are limited, and surgical treatments can be associated with high rates of infection and other complications. One treatment, sacral nerve stimulation (SNS), is approved for FI in Europe. A large multicenter trial was conducted in North America and Australia to assess the efficacy of SNS in patients with chronic fecal incontinence. The aim of this report was to analyze the infectious complication rates in that trial.

METHODS

Adult patients with a history of chronic fecal incontinence were enrolled into this study. Those patients who fulfilled study inclusion/exclusion criteria and demonstrated greater than two FI episodes per week underwent a 2-week test phase of SNS. Patients who showed a > or = 50% reduction in incontinent episodes and/or days per week underwent chronic stimulator implantation. Adverse events were reported to the sponsor by investigators at each study site and then coded. All events coded as implant site infection were included in this analysis.

RESULTS

One hundred twenty subjects (92% female, 60.5 +/- 12.5 years old) received a chronically implanted InterStim Therapy device (Medtronic, Minneapolis, MN, USA). Patients were followed for an average of 28 months (range 2.2-69.5). Thirteen of the 120 implanted subjects (10.8%) reported infection after the chronic system implant. One infection spontaneously resolved and five were successfully treated with antibiotics. Seven infections (5.8%) required surgical intervention, with infections in six patients requiring full permanent device explantation. The duration of the test stimulation implant procedure was similar between the infected group (74 min) and the non-infected group (74 min). The average duration of the chronic neurostimulator implant procedure was also similar between the infected (39 min) and non-infected group (37 min). Nine infections occurred within a month of chronic system implant and the remaining four infections occurred more than a year from implantation. While the majority (7/9) of the early infections was successfully treated with observation, antibiotics, or system replacement, all four of the late infections resulted in permanent system explantation.

CONCLUSION

SNS for FI resulted in a relatively low infection rate. This finding is especially important because the only other Food and Drug Administration-approved treatment for end-stage FI, the artificial bowel sphincter, reports a much higher rate. Combined with its published high therapeutic success rate, this treatment has a positive risk/benefit profile.