Mechanisms and potential applications of intestinal electrical stimulation

[Severe small bowel involvement and chronic intestinal pseudo-obstruction in systemic sclerosis (scleroderma): Pathophysiological, diagnostic and therapeutic basis, including parenteral nutrition]

Gastrointestinal involvement in systemic sclerosis can be severe, reaching the critical point of chronic intestinal pseudo-obstruction, secondary to major disorders of small bowel motility. It is associated with some clinical and biological characteristics, in particular the positivity of anti-fibrillarin/U3RNP antibodies. Chronic intestinal pseudo-obstruction (CIPO) is complicated by a small intestinal bacterial overgrowth that requires cyclic antibiotic therapy. CIPO leads to a reduction of the food intake, due to painful symptoms, nausea and vomiting caused by meals, and ultimately to severe malnutrition. Meal splitting is often transiently effective and patients require exogenous nutritional support, mostly parenteral. Systemic sclerosis is not an obstacle to initiation and long-term continuation of parenteral nutrition and central venous catheter implantation is not associated with an increased risk of cutaneous or infectious complications. However, continuation of long-term parenteral nutrition requires monitoring in an expert nutrition center in order to adapt nutritional volumes and intakes and to limit potentially fatal cardiac and hepatobiliary complications. In addition to nutrition, prokinetic treatments, whose side effects must be known, can be associated. Invasive procedures, whose risk-benefit ratio must be carefully assessed, can also be used to treat symptoms exclusively.

An ingestible self-propelling device for intestinal reanimation

Postoperative ileus (POI) is the leading cause of prolonged hospital stay after abdominal surgery and is characterized by a functional paralysis of the digestive tract, leading to symptoms such as constipation, vomiting, and functional obstruction. Current treatments are mainly supportive and inefficacious and yield acute side effects. Although electrical stimulation studies have demonstrated encouraging pacing and entraining of the intestinal slow waves, no devices exist today to enable targeted intestinal reanimation. Here, we developed an ingestible self-propelling device for intestinal reanimation (INSPIRE) capable of restoring peristalsis through luminal electrical stimulation. Optimizing mechanical, material, and electrical design parameters, we validated optimal deployment, intestinal electrical luminal contact, self-propelling capability, safety, and degradation of the device in ex vivo and in vivo swine models. We compared the INSPIRE's effect on motility in models of normal and depressed motility and chemically induced ileus. Intestinal contraction improved by 44% in anesthetized animals and up to 140% in chemically induced ileus cases. In addition, passage time decreased from, on average, 8.6 days in controls to 2.5 days with the INSPIRE device, demonstrating significant improvement in motility. Luminal electrical stimulation of the intestine via the INSPIRE efficaciously restored peristaltic activity. This noninvasive option offers a promising solution for the treatment of ileus and other motility disorders.

Electrical pulse stimulation parameters modulate N2a neuronal differentiation

Electrical pulse stimulation has been used to enhance the differentiation or proliferation of neuronal progenitor cells in tissue engineering and cancer treatment. Therefore, a comprehensive investigation of the effects caused by its parameters is crucial for improvements in those fields. We propose a study of pulse parameters, to allow the control of N2a cell line fate and behavior. We have focused on designing an experimental setup that allows for the knowledge and control over the environment and the stimulation signals applied. To map the effects of the stimulation on N2a cells, their morphology and the cellular and molecular reactions induced by the pulse stimulation have been analyzed. Immunofluorescence, rt-PCR and western blot analysis have been carried out for this purpose, as well as cell counting. Our results show that low-amplitude electrical pulse stimulation promotes proliferation of N2a cells, whilst amplitudes in the range 250 mV/mm-500 mV/mm induce differentiation. Amplitudes higher than 750 mV/mm produce cell damage at low frequencies. For high frequencies, large amplitudes are needed to cause cell death. An inverse relation has been found between cell density and pulse-induced neuronal differentiation. The best condition for neuronal differentiation was found to be 500 mV/mm at 100 Hz. These findings have been confirmed by up-regulation of the Neurod1 gene. Our preliminary study of the molecular effects of electrical pulse stimulation on N2a offers premonitory clues of the PI3K/Akt/GSK-3β pathway implications on the neuronal differentiation process through ES. In general, we have successfully mapped the sensitivity of N2a cells to electrical pulse stimulation parameters.

An efficient online peak detection algorithm for synchronized intestinal electrical stimulation and its application for treating diabetes

Obesity is one of leading risk factors for type 2 diabetes and other types of chronic diseases. Synchronized intestinal electrical stimulation (SIES) has been explored for treating obesity and diabetes. In SIES, electrical stimulation is delivered to the small intestine in synchronization with the intrinsic intestinal myoelectrical activity (its basic rhythm is called slow wave) and therefore, the accurate detection of intestinal slow waves is critically important for SIES. The aim of this study is to detect the peaks in intestinal slow waves in real-time based on the automatic multiscale peak detection (AMPD) method. In this paper, we introduce an efficient technique for real-time detection of peaks in intestinal slow waves. The presented method is based on peak estimation of a given quasi-periodic signal using the AMPD method. This method uses a multi-scale approach to identify the peaks of the intestinal slow waves with high detection accuracy and a minimal delay. Throughout the experiments, the multi-scale technique is used to estimate the quasi-periodic signals using different signal-to-noise ratio, λ (optimal scale), and the "lag" β (number of datapoints for right hand estimation) as important performance factors. The performance of the presented method is also calculated and utilized in the comparison process for 10 datasets of the intestinal slow waves from rats at λ = 150 ms and two values of β = 100 ms and 150 ms. The experimental results show that the presented method has good overall accuracy for online peak detection while maintaining low memory and computational complexity. Numerically, the overall accuracy is above 90%, and 98% for the rodent intestinal slow waves at a time-lag of 150 ms. The developed SIES system has been applied to successfully reduce postprandial blood glucose in a rodent model of hyperglycemia. In conclusion, the developed algorithm is adequate for on-line peak detection of the intestinal slow waves; the SIES method used the developed peak detection algorithm which is effective in reducing postprandial blood glucose in a rodent model of hyperglycemia.

Correlations between EEG and intestinal electrical stimulation

Many diseases affect the autonomous nervous system and the central nervous system simultaneously, for example Parkinson's disease or irritable bowel syndrome. To study neurophysiologic interactions between the intestinal electrical activity and the electroencephalography (EEG) pattern of the brain, we combined intestinal electrical stimulation (IES) and non-invasive telemetric full-band DC EEG recordings in an acute pig-model. Intestinal motility was monitored with accelerometers. Brain activity was analyzed with regard to network driven phenomena like phase amplitude coupling (PAC) within two time-windows: 1 min after IES (early response) and 3 min after stimulation (late response). Here we present the results for two stimulation sites (small intestine, colon) and two parietal scalp-EEG channels (right and left somatosensory cortex region). Electrical stimulation consisted of a 30 or 130 Hz pulse. In summary, the PAC modulation index at a parietal EEG recording position is decreased after IES. This effect is in line with an inhibitory effect of our IES protocol regarding peristalsis. The surprisingly strong effects of IES on network driven EEG patterns may be translated into new therapeutic techniques and/or diagnostic tools in the future. Furthermore, analytic tools, operating on sparse datasets, may be ideally suited for the integration in implantable intestinal pacemakers as feedback system.

Low-frequency electrical stimulation promotes the recovery of gastrointestinal motility following gynecological laparoscopy (Review)

The rapid recovery of gastrointestinal transit is critical for clinical recovery following laparoscopic procedures, including gynecological laparoscopies (GLs). Rehabilitation interventions post-surgery may provide significant prevention against early post-operative gastrointestinal motility disorders and maid aid in the acceleration of post-operative recovery in patients undergoing GLs. Among others, low-frequency electrical stimulation (LFES) has been demonstrated to pronouncedly mitigate the symptoms caused by gastrointestinal motility disorders; thus, this has attracted increasing attention over the past decade. The present study aimed to present an overview of the efficacy and application of LFES in gastrointestinal motility recovery following GL procedures.

Electronic Bypass for Diabetes: Optimization of Stimulation Parameters and Mechanisms of Glucagon-Like Peptide-1

OBJECTIVES

Intestinal electrical stimulation (IES) has been proposed for treating diabetes; however, its parameters need to be further systematically optimized. This study aimed to optimize the parameters of IES and investigate its possible mechanisms involving glucagon-like peptide-1 (GLP-1) in diabetic rats.

MATERIALS AND METHODS

Thirty-six high-fat diet-induced diabetic rats were chronically implanted with a pair of bipolar electrodes at the duodenum for IES. The oral glucose tolerance test (OGTT) was performed in a number of sessions with IES using different parameters and biphasic charge-balanced waveforms to derive the best values for train on-time, pulse frequency, and pulse width. Incretin hormones such as GLP-1 were assessed and the GLP-1 antagonist Exendin 9-39 was used to assess the role of GLP-1 in the ameliorating effect of IES on hyperglycemia.

RESULTS

The most effective IES parameters in reducing blood glucose (BG) during the OGTT were derived: 1.2 sec on, 0.3 sec off, 80 Hz, 3 msec. IES with these parameters reduced BG level by at least 29% from 15 min to 180 min (p < 0.05 for all points, N = 10). IES with these stimulation parameters increased plasma GLP-1 level at 30 min, 60 min, 90 min and gastric inhibitory peptide (GIP) level at 30 min (N = 8). Exendin 9-39 blocked the inhibitory effect of IES on BG (p > 0.05, IES + Exendin 9-39 vs. sham-IES, N = 8).

CONCLUSION

IES with the most effective parameters derived in this study improves hyperglycemia in diabetic rats. The ameliorating effect of IES on hyperglycemia is attributed to the enhanced release of GLP-1. IES has great potential for treating diabetes.

Electroacupuncture Alleviates Diabetic Peripheral Neuropathy by Regulating Glycolipid-Related GLO/AGEs/RAGE Axis

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus (DM) and affects over one-third of all patients. Neuropathic pain and nerve dysfunction induced by DM is related to the increase of advanced glycation end products (AGEs) produced by reactive dicarbonyl compounds in a hyperglycemia environment. AGEs induce the expression of pro-inflammatory cytokines via the main receptor (RAGE), which has been documented to play a crucial role in the pathogenesis of diabetic peripheral neuropathy. Electroacupuncture (EA) has been reported to have a positive effect on paralgesia caused by various diseases, but the mechanism is unclear. In this study, we used high-fat-fed low-dose streptozotocin-induced rats as a model of type 2 diabetes (T2DM). Persistent metabolic disorder led to mechanical and thermal hyperalgesia, as well as intraepidermal nerve fiber density reduction and nerve demyelination. EA improved neurological hyperalgesia, decreased the pro-inflammatory cytokines, reduced the generation of AGEs and RAGE, and regulated the glyoxalase system in the EA group. Taken together, our study suggested that EA plays a role in the treatment of T2DM-induced DPN, and is probably related to the regulation of metabolism and the secondary influence on the GLO/AGE/RAGE axis.

Enteric Neuromodulation for the Gut and Beyond

The small intestine is the longest organ in the human body, spanning a length of ∼5 m and compartmentalized into three distinct regions with specific roles in maintenance of comprehensive homeostasis. Along its length exists as a unique and independent system-called the enteric nervous system (ENS)-which coordinates the multitude of functions continuously around the clock. Yet, with so many vital roles played, the functions, relationships, and roles of the small intestine and ENS remain largely elusive. This fundamental hole in the physiology of the small intestine and ENS introduces a substantial number of challenges when attempting to create bioelectronic approaches for treatment of various disorders originating in the small intestine. Here, we review existing therapeutic options for modulating the small intestine, discuss fundamental gaps that must be addressed, and highlight novel methods and approaches to consider for development of bioelectronic approaches aiming to modulate the small intestine.

Use of Bioelectronics in the Gastrointestinal Tract

Gastrointestinal (GI) motility disorders are major contributing factors to functional GI diseases that account for >40% of patients seen in gastroenterology clinics and affect >20% of the general population. The autonomic and enteric nervous systems and the muscles within the luminal GI tract have key roles in motility. In health, this complex integrated system works seamlessly to transport liquid, solid, and gas through the GI tract. However, major and minor motility disorders occur when these systems fail. Common functional GI motility disorders include dysphagia, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, chronic intestinal pseudo-obstruction, postoperative ileus, irritable bowel syndrome, functional diarrhea, functional constipation, and fecal incontinence. Although still in its infancy, bioelectronic therapy in the GI tract holds great promise through the targeted stimulation of nerves and muscles.

Intestinal Electrical Stimulation to Increase the Rate of Peristalsis

BACKGROUND

Pediatric gastrointestinal motility disorders are a large and broad group. Some of these disorders have been effectively treated with electrical stimulation. The goal of our present study is to determine whether the rate of intestinal peristalsis can be increased with electrical stimulation.

METHODS

Juvenile mini-Yucatan pigs were placed under general anesthesia and a short segment of the jejunum was transected. Ultrasound gel was placed inside the segment. The segment of the jejunum was first monitored for 20 min under no stimulation, followed by direct electrical stimulation using a planar electrode. The gel extruded out of the intestine via peristalsis was collected and weighed for each 20-min time interval.

RESULTS

Effective delivery of the current to the intestine was confirmed via direct measurements. When there was no direct intestinal electrical stimulation, an average of 0.40 g of gel was expelled in 20 min, compared to 1.57 g of gel expelled during direct electrical stimulation (P < 0.01).

CONCLUSIONS

Direct intestinal electrical stimulation accelerates the transit of gastrointestinal contents. This approach may be useful in the treatment of a range of pediatric motility disorders.

Accelerometer-Based Assessment of Intestinal Peristalsis: Toward Miniaturized Low-Power Solutions for Intestinal Implants

Intestinal electrical stimulation via implants is already used to treat several disorders like constipation or incontinence. Stimulation parameters are most often empiric and not based on systematic studies. One prerequisite to evaluate effects of intestinal electrical stimulation is a direct assessment of intestinal motility. Some common methods are strain gauge transducers or manometry. With both the methods, it is not possible to record the exact 3-D movement. Therefore, we established a new method to record gastrointestinal motility with ultraminiaturized accelerometers, directly glued to the outer surface of the stomach, small intestine, and colon. With this technique, we were able to record precise local motility changes after electrical stimulation. Due to the low energy demand and the small size of the system, it is potentially useful for chronic measurements at multiple sites of the intestinal tract. We will present our first results regarding stimulation-dependent motility changes using up to eight implanted accelerometers in an acute pig model.

A Wireless Implant for Gastrointestinal Motility Disorders

Implantable functional electrical stimulation (IFES) has demonstrated its effectiveness as an alternative treatment option for diseases incurable pharmaceutically (e.g., retinal prosthesis, cochlear implant, spinal cord implant for pain relief). However, the development of IFES for gastrointestinal (GI) tract modulation is still limited due to the poorly understood GI neural network (gut⁻brain axis) and the fundamental difference among activating/monitoring smooth muscles, skeletal muscles and neurons. This inevitably imposes different design specifications for GI implants. This paper thus addresses the design requirements for an implant to treat GI dysmotility and presents a miniaturized wireless implant capable of modulating and recording GI motility. This implant incorporates a custom-made system-on-a-chip (SoC) and a heterogeneous system-in-a-package (SiP) for device miniaturization and integration. An in vivo experiment using both rodent and porcine models is further conducted to validate the effectiveness of the implant.

Effect of retrograde colonic electrical stimulation on colonic transit and stress-induced visceral hypersensitivity in rats with irritable bowel syndrome

OBJECTIVE

To evaluate the effects of retrograde colonic electrical stimulation (RCES) with trains of short pulses and RCES with long pulses on colonic transit in irritable bowel syndrome (IBS) rats and to investigate whether stress-induced visceral hypersensitivity could be alleviated by RCES so as to find a valuable new approach for IBS treatment.

METHODS

A total of 48 male rats were randomly divided into model group and control group. Visceral hypersensitivity model was induced by a 6-day HIS protocol composed of two stressors, restraint stress for 40 min and forced swimming stress for 20 min. The extent of visceral hypersensitivity was quantified by electromyography and abdominal withdrawal reflex scores (AWRs) of colorectal distension (use a balloon) at different pressures. After the modeling, all rats were equipped with electrodes in descending colon for retrograde electrical stimulation and a PE tube for perfusing phenol red saline solution in the ileocecus. After recovering from surgery, RCES with long pulses, RCES with trains of short pulses, and sham RCES were performed in colonic serosa of rats for 40 min in six groups of 8 each, including three groups of visceral hypersensitivity rats and three groups of health rats. Colonic transit was assessed by calculating the output of phenol red from the anus every 10 min for 90 min. Finally, the extent of visceral hypersensitivity will be quantified again in model group.

RESULTS

After the 6-day HIS protocol, the HIS rats displayed an increased sensitivity to colorectal distention, compared to control group at different distention pressures (P < 0.01). CRES with trains of short pulses and long pulses significantly attenuated the hypersensitive responses to colorectal distention in the HIS rats compared with sham RCES group (P < 0.01). The effects of RCES on rats colon transmission: In the IBS rats, the colonic emptying were (77.4 ± 3.4)%, (74.8 ± 2.4)% and (64.2 ± 1.6)% in the sham RCES group, long pulses group and trains of short pulses group at 90 min; In healthy rats, The colonic emptying was (65.2 ± 3.5)%, (63.5 ± 4.0)% and (54.0 ± 2.5)% in the sham RCES group, long pulses group and trains of short pulses group at 90 min.

CONCLUSION

RCES with long pulses and RCES with trains of short pulses can significantly alleviate stress-induced visceral hypersensitivity. RCES with trains of short pulses has an inhibitory effect of colonic transit, both in visceral hypersensitivity rats and healthy rats.

Electrical therapies for gastrointestinal motility disorders

Gastrointestinal (GI) motility disorders are common in clinical settings, including esophageal motility disorders, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, chronic intestinal pseudo-obstruction, post-operative ileus, irritable bowel syndrome, diarrhea and constipation. While a number of drugs have been developed for treating GI motility disorders, few are currently available. Emerging electrical stimulation methods may provide new treatment options for these GI motility disorders. Areas covered: This review gives an overview of electrical therapies that have been, and are being developed for GI motility disorders, including gastroesophageal reflux, functional dyspepsia, gastroparesis, intestinal motility disorders and constipation. Various methods of gastrointestinal electrical stimulation are introduced. A few methods of nerve stimulation have also been described, including spinal cord stimulation and sacral nerve stimulation. Potentials of electrical therapies for obesity are also discussed. PubMed was searched using keywords and their combinations: electrical stimulation, spinal cord stimulation, sacral nerve stimulation, gastrointestinal motility and functional gastrointestinal diseases. Expert commentary: Electrical stimulation is an area of great interest and has potential for treating GI motility disorders. However, further development in technologies (devices suitable for GI stimulation) and extensive clinical research are needed to advance the field and bring electrical therapies to bedside.

Acceleration of small bowel transit in a canine hypermotility model with intestinal electrical stimulation

OBJECTIVE

Few studies have been performed on the effect of intestinal electrical stimulation (IES) on intestinal dysmotility. This study aimed to investigate the small intestine transit (SIT) in a canine model of intestinal hypermotility when applying IES.

METHOD

Six hound bitches were surgically prepared with two chronic intestinal fistulas, intestinal serosal electrodes of which the proximal pair was used for serosal IES. Pacing wires were attached to a manometric catheter for mucosal IES. A nitrogen oxide synthase inhibitor, Nω-nitro-L-arginine (LNNA) was used to induce intestinal motility. SIT was measured during IES. The study consisted of four randomized sessions: session 1 (LNNA), session 2 (LNNA plus serosal IES), session 3 (LNNA plus mucosal IES) and session 4 (control).

RESULTS

The intestine transit was slowed down from 31.7 ± 6.1 min in the control session to 49.0 ± 6.2 min after using LNNA (P = 0.003). Both mucosal and serosal IES accelerated SIT compared with the LNNA session. The SIT time was reduced to 17.7 ± 3.4 min in the mucosal IES session (P = 0.006 vs. LNNA) and 27.5 ± 6.3 min in the serosal IES session (P = 0.020 vs. LNNA). No difference was noted in the SIT time between mucosal and serosal IES (P = 0.128).

CONCLUSION

IES significantly accelerates delayed SIT in a hypermotility model and intraluminal stimulation is as effective as a serosal one for IES, suggesting that IES may have a therapeutic potential for improving intestinal motility.

Changes of neuronal activities after gut electrical stimulation with different parameters and locations in lateral hypothalamus area of obese rats

This study tested the effects of the gastrointestinal pulse train electrical stimulation with different parameters and at different locations on the neuronal activities of the lateral hypothalamus area (LHA) in obese rats in order to find the optimal stimulation parameter and location. Eight gastric electrical stimulations (GES) with different parameters were performed and the neuronal activities of gastric-distension responsive (GD-R) neurons in LHA were observed. The effects of stimulations with 8 parameters were compared to find the optimal parameter. Then the optimal parameter was used to perform electrical stimulation at duodenum and ileum, and the effects of the duodenal and ileac stimulation on the GD-R neurons in LHA were compared with the gastric stimulation of optimal parameter. The results showed that GES with the lowest energy parameter (0.3 ms, 3 mA, 20 Hz, 2 s on, 3 s off) activated the least neurons. The effects of GES with other parameters whose pulse width was 0.3 ms were not significantly different from those of the lowest energy parameter. Most gastric stimulations whose pulse width was 3 ms activated more LHA neurons than the smallest energy parameter stimulation, and the effects of those 3 ms gastric stimulations were similar. Accordingly, the lowest energy parameter was recognized as the optimal parameter. The effects of stimulations with the optimal parameter at stomach, duodenum and ileum on the LHA neuronal activities were not different. Collectively, gastrointestinal electrical stimulation (GIES) with relatively large pulse width might have stronger effects to the neuronal activities of GD-R neurons in LHA of obese rats. The effects of the GIES at different locations (stomach, duodenum and ileum) on those neurons are similar, and GES is preferential because of its easy clinical performance and safety.

A gastrointestinal electrical stimulation system based on transcutaneous power transmission technology

Electrical stimulation has been suggested as a possible treatment for various functional gastrointestinal disorders (FGID). This paper presents a transcutaneous power supplied implantable electrical stimulation system. This technology solves the problem of supplying extended power to an implanted electrical stimulator. After implantation, the stimulation parameters can be reprogrammed by the external controller and then transmitted to the implanted stimulator. This would enable parametric studies to investigate the efficacy of various stimulation parameters in promoting gastrointestinal contractions. A pressure detector in the internal stimulator can provide real-time feedback about variations in the gastrointestinal tract. An optimal stimulation protocol leading to cecal contractions has been proposed: stimulation bursts of 3 ms pulse width, 10 V amplitude, 40 Hz frequency, and 20 s duration. The animal experiment demonstrated the functionality of the system and validated the effects of different stimulation parameters on cecal contractions.

Advances in research of colonic electrical stimulation

In recent years great attention has been paid to the study of colonic electrical stimulation. Colonic electrical stimulation is expected to become a valuable option for treatment of gastrointestinal dysfunction. This article reviews the classification, mechanisms and clinical applications of colonic electrical stimulation.

Review article: the assessment and management of chronic severe gastrointestinal dysmotility in adults

BACKGROUND

The characterisation and management of chronic severe gastrointestinal (GI) dysmotility are challenging. It may cause intestinal failure requiring home parenteral nutrition (HPN).

AIMS

To review the presentation, aetiology, characterisation, management and outcome of chronic severe GI dysmotility, and to suggest a pragmatic management algorithm.

METHODS

PubMed search was performed up to December 2012 using appropriate search terms, restricted to human articles and reviewed for relevance. Segmental dysmotility, acute ileus, functional syndromes and non-English articles were excluded. Evidence and recommendations were evaluated using the GRADE system.

RESULTS

In total, 721 relevant articles were reviewed. A coherent and definitive picture is hampered by overlapping classification systems using multi-modal characterisation methods, subject to pitfalls and some requiring further validation. The literature is confined to case series with no randomised trials. Fewer than 20% undergo full thickness jejunal biopsy, which are otherwise labelled idiopathic. However, in studies with up to 80% biopsy rates, neuromuscular abnormalities may be found in 90%. Between 14% and 50% will require HPN, comprising 8-14% of all HPN patients, of which 2/3 are primary/idiopathic and 1/3 secondary, with scleroderma being the leading secondary cause. Ten-year  mortality ranges from 13% to 35% and is worst in elderly scleroderma patients. Management includes limited treatments for secondary causes, prokinetics, symptom palliation, psychological support, nutrition, hydration and judicious surgery.

CONCLUSIONS

Severe dysmotility often remains idiopathic. It is rarely possible to alter disease trajectory; consequently, prognosis may be poor. Multi-disciplinary teams in a specialist setting can improve outcomes. Graded recommendations are enumerated and a pragmatic algorithm is suggested.

Colonic electrical stimulation for the treatment of slow-transit constipation: a preliminary pilot study

BACKGROUND

Electrical stimulation of the gastrointestinal tract is an attractive concept. In this article we report on a procedure for electrical colonic pacing due to intramuscular electrode placement for slow-transit constipation and some preliminary results.

METHODS

From January 2011 to December 2012, all consecutive patients affected by constipation and evaluated in our Pelvic Floor Center were prospectively assessed. Patients who underwent colonic electrical stimulation were evaluated for the present study.

RESULTS

In the study period, 256 patients were evaluated for constipation; 58% were identified as having obstructed defecation syndrome, 27.3% with irritable bowel syndrome or mixed forms, 4% with pelvic floor dyssynergia, and 10.5% (27 patients) as having slow-transit constipation. After failure of all the maximal conventional therapies, two patients, candidates for colectomy, agreed to undergo colonic electrical stimulation before a resective treatment. Both patients were females, aged 34 and 29 years, and were suffering from severe constipation since childhood. The follow-up was 19 and 6 months. The number of bowel movements per week increased from 0.3 to 3.5 in the first patient and from 0.5 to 2.5 in the second patient. Both patients no longer needed laxatives, enemas, or any other treatment. The hospital stay was 4 days, the mean operative time was 120 min, and no complications were reported.

CONCLUSIONS

Colonic pacing seems to be feasible and shows positive results. Further studies are required with a larger number of patients and a longer follow-up period to confirm the role of this promising treatment for slow-transit constipation.

Diffused and sustained inhibitory effects of intestinal electrical stimulation on intestinal motility mediated via sympathetic pathway

OBJECTIVE

The aims were to investigate the energy-dose response effect of intestinal electrical stimulation (IES) on small bowel motility, to compare the effect of forward and backward IES, and to explore the possibility of using intermittent IES and mechanism of IES on intestinal motility.

MATERIALS AND METHODS

Five dogs implanted with a duodenal cannula and one pair of intestinal serosal electrodes were studied in five sessions: 1) energy-dose response study; 2) forward IES; 3) backward IES; 4) intermittent IES vs. continuous IES; 5) administration of guanethidine. The contractile activity and tonic pressure of the small intestine were recorded. The duration of sustained effect after turning off IES was manually calculated.

RESULTS

1) IES with long pulse energy dose dependently inhibited contractile activity and tonic pressure of the small intestine (p < 0.001). 2) The duration of sustained inhibitory effect of IES on the small intestine depended on the energy of IES delivered (p < 0.001). 3) The potency of the inhibitory effect was the same between forward and backward IES. 4) The efficacy of intermittent IES was the same as continuous IES in inhibiting motility of the small intestine. 5) Guanethidine blocked the inhibitory effect of IES on intestinal motility.

CONCLUSIONS

IES with long pulses inhibits small intestinal motility; the effect is energy-dose dependent, diffused, and sustained. Intermittent IES has the same efficacy as the continuous IES in inhibiting small intestinal motility. Forward and backward IES have similar inhibitory effects on small bowel motility. This IES-induced inhibitory effect is mediated via the sympathetic pathway.

Gastric electrical stimulation for the treatment of obesity: from entrainment to bezoars-a functional review

GROWING WORLDWIDE OBESITY EPIDEMIC HAS PROMPTED THE DEVELOPMENT OF TWO MAIN TREATMENT STREAMS: (a) conservative approaches and (b) invasive techniques. However, only invasive surgical methods have delivered significant and sustainable benefits. Therefore, contemporary research exploration has focused on the development of minimally invasive gastric manipulation methods featuring a safe but reliable and long-term sustainable weight loss effect similar to the one delivered by bariatric surgeries. This antiobesity approach is based on placing external devices in the stomach ranging from electrodes for gastric electrical stimulation to temporary intraluminal bezoars for gastric volume displacement for a predetermined amount of time. The present paper examines the evolution of these techniques from invasively implantable units to completely noninvasive patient-controllable implements, from a functional, rather than from the traditional, parametric point of view. Comparative discussion over the available pilot and clinical studies related to gastric electrical stimulation outlines the promises and the fallacies of this concept as a reliable alternative anti-obesity strategy.

Treatment of high-frequency gastric electrical stimulation for gastroparesis

BACKGROUND AND AIMS

The aim of this study was to assess the effects of gastric electrical stimulation (GES) on symptoms and gastric emptying in patients with gastroparesis, and the effects of GES on the three subgroups of gastroparesis.

METHODS

A literature search of clinical trials using high-frequency GES to treat patients with gastroparesis from January 1995 to January 2011 was performed. Data on the total symptom severity score (TSS), nausea severity score, vomiting severity score, and gastric emptying were extracted and analyzed. The statistic effect index was weighted mean differences.

RESULTS

Ten studies (n = 601) were included in this study. In the comparison to baseline, there was significant improvement of symptoms and gastric emptying (P < 0.00001). It was noted that GES significantly improved both TSS (P < 0.00001) and gastric retention at 2 h (P = 0.003) and 4 h (P < 0.0001) in patients with diabetic gastroparesis (DG), while gastric retention at 2 h (P = 0.18) in idiopathic gastroparesis (IG) patients, and gastric retention at 4 h (P = 0.23) in postsurgical gastroparesis (PSG) patients, did not reach significance.

CONCLUSIONS

Based on this meta-analysis, the substantial and significant improvement of symptoms and gastric emptying, and the good safety we observed, indicate that high-frequency GES is an effective and safe method for treating refractory gastroparesis. DG patients seem the most responsive to GES, both subjectively and objectively, while the IG and PSG subgroups are less responsive and need further research.

Gastric stimulation for weight loss

The prevalence of obesity is growing to epidemic proportions, and there is clearly a need for minimally invasive therapies with few adverse effects that allow for sustained weight loss. Behavior and lifestyle therapy are safe treatments for obesity in the short term, but the durability of the weight loss is limited. Although promising obesity drugs are in development, the currently available drugs lack efficacy or have unacceptable side effects. Surgery leads to long-term weight loss, but it is associated with morbidity and mortality. Gastric electrical stimulation (GES) has received increasing attention as a potential tool for treating obesity and gastrointestinal dysmotility disorders. GES is a promising, minimally invasive, safe, and effective method for treating obesity. External gastric pacing is aimed at alteration of the motility of the gastrointestinal tract in a way that will alter absorption due to alteration of transit time. In addition, data from animal models and preliminary data from human trials suggest a role for the gut-brain axis in the mechanism of GES. This may involve alteration of secretion of hormones associated with hunger or satiety. Patient selection for gastric stimulation therapy seems to be an important determinant of the treatment’s outcome. Here, we review the current status, potential mechanisms of action, and possible future applications of gastric stimulation for obesity.

Hypoglycemic effects of intraluminal intestinal electrical stimulation in healthy volunteers

BACKGROUND

Intestinal electrical stimulation (IES) has been shown to delay gastric emptying and reduce nutrient absorption in humans. The aim of this study was to investigate the effect of IES using an intraluminal method on postprandial blood glucose.

METHODS

An oral glucose tolerance test with 150 g of glucose was performed in 10 healthy volunteers with and without IES (13 pulses/min, 300 ms and 5 mA). An intraluminal catheter with a pair of ring electrodes was incubated into the duodenum under endoscopy and used for IES. Gastric emptying was performed simultaneously using an established ultrasonic technique.

RESULTS

(1) IES significantly decreased the postprandial glucose level from 15 min to 90 min after the glucose load. (2) The serum insulin level at 30 min but not other times after the meal was lower in the IES session than that in the control session (p = 0.06). (3) The half-time of gastric emptying with IES was increased from 27 ± 4.8 min in the control session to 36 ± 8.5 min with IES (p < 0.01). (4) The symptoms score of dyspepsia were almost the same between the two sessions except that IES induced a slightly higher nausea symptom score.

CONCLUSIONS

IES decreases postprandial blood glucose possibly by delaying gastric emptying and other unknown mechanisms and the intraluminal method of IES may serve as an excellent screening and research tool for various applications of IES. Further clinical studies are needed to explore therapeutic potentials of IES for diabetes.

Duodenum electrical stimulation delays gastric emptying, reduces food intake and accelerates small bowel transit in pigs

Duodenum electrical stimulation (DES) has been shown to delay gastric emptying and reduce food intake in dogs. The aim of this study was to investigate the effects of DES on gastric emptying, small bowel transit and food intake in pigs, a large animal model of obesity. The study consisted of three experiments (gastric emptying, small bowel transit, and food intake) in pigs implanted with internal duodenal electrodes for DES and one or two duodenal cannulas for gastric emptying and small bowel transit. We found that (i) gastric emptying was dose-dependently delayed by DES of different stimulation parameters; (ii) small bowel transit was significantly accelerated with continuous DES in proximal intestine but not with intermittent DES; (iii) DES significantly reduced body weight gain with 100% duty cycle (DC), but not with DES with 40% DC. A marginal difference was noted in food intake among 100% DC session, 40% DC session, and control session. DES with long pulses energy-dependently inhibits gastric emptying in pigs. DES with appropriate parameters accelerates proximal small bowel transit in pigs. DES reduces body weight gain in obese pigs, and this therapeutic effect on obesity is mediated by inhibiting gastric emptying and food intake, and may also possibly by accelerating intestinal transit. DES may have a potential application to treat patients with obesity.

Electrical stimulation of the isolated rat intestine in the presence of nutrient stimulus enhances glucagon-like peptide-1 release

The release of small intestinal hormones by constituents of ingested food, such as fatty acids, is integral to post-prandial responses that reduce food intake. Recent evidence suggests that small intestinal electrical stimulation reduces food intake, although the mechanism of action is debated. To test the hypothesis that intestinal stimulation directly alters hormone release locally we used isolated rat distal ileum and measured glucagon-like peptide-1 (GLP-1) released in the presence or absence of linoleic acid (LA) and electrical field stimulation (EFS). Intact segments were oriented longitudinally between bipolar stimulating electrodes in organ bath chambers containing modified Krebs-Ringers bicarbonate (KRB) buffer including protease inhibitors. Incubation in LA (3 mg ml(-1)) for 45 min increased GLP-1 concentration (21.9 +/- 2.6 pM versus KRB buffer alone 3.6 +/- 0.1 pM). Eleven electrical stimulation conditions were tested. In the presence of LA none of the stimulation conditions inhibited LA-evoked GLP-1 release, whereas two high frequency short pulse widths (14 V, 20 Hz, 5 ms and 14 V, 40 Hz, 5 ms) and one low frequency long pulse width (14 V, 0.4 Hz, 300 ms) EFS conditions enhanced LA-evoked GLP-1 release by >250%. These results are consistent with a local effect of intestinal electrical stimulation to enhance GLP-1 release in response to luminal nutrients in the intestines. Enhancing hormone release could improve the efficacy of intestinal electrical stimulation and provide a potential treatment for obesity and metabolic conditions.