Gastric Neuromodulation With Enterra System for Nausea and Vomiting in Patients With Gastroparesis

[A New Paradigm in Diagnosing Functional Gastroduodenal Disorders: High-Resolution Electrogastrography]

High-resolution electrogastrography (HR-EGG) presents a new paradigm in diagnosing and treating functional gastroduodenal disorders. Unlike traditional electrogastrography, HR-EGG allows for a more precise analysis of the gastric electrical activity, offering improved diagnostic accuracy. Recent studies have revealed the clinical potential of HR-EGG, particularly in detecting abnormal electrical patterns in patients with functional dyspepsia and gastroparesis, supporting the development of novel therapeutic strategies. The non-invasive HR-EGG method has shown promise in identifying new biomarkers. Moreover, further integration of artificial intelligence, is expected to enhance diagnostic efficiency and develop more refined treatment models for functional gastrointestinal disorders.

Noninvasive electrical neuromodulation for gastrointestinal motility disorders

INTRODUCTION

Gastrointestinal motility disorders are highly prevalent without satisfactory treatment. noninvasive electrical neuromodulation is an emerging therapy for treating various gastrointestinal motility disorders.

AREAS COVERED

In this review, several emerging noninvasive neuromodulation methods are introduced, including transcutaneous auricular vagal nerve stimulation, percutaneous auricular vagal nerve stimulation, transcutaneous cervical vagal nerve stimulation, transcutaneous electrical acustimulation, transabdominal interference stimulation, tibial nerve stimulation, and translumbosacral neuromodulation therapy. Their clinical applications in the most common gastrointestinal motility are discussed, including gastroesophageal reflux disease, functional dyspepsia, gastroparesis, functional constipation, irritable bowel syndrome, and fecal incontinence. PubMed database was searched from 1995 to June 2023 for relevant articles in English.

EXPERT OPINION

Noninvasive neuromodulation is effective and safe in improving both gastrointestinal symptoms and dysmotility; it can be used when pharmacotherapy is ineffective. Future directions include refining the methodology, improving device development and understanding mechanisms of action.

Systemic sclerosis gastrointestinal dysmotility: risk factors, pathophysiology, diagnosis and management

Nearly all patients with systemic sclerosis (SSc) are negatively affected by dysfunction in the gastrointestinal tract, and the severity of gastrointestinal disease in SSc correlates with high mortality. The clinical complications of this dysfunction are heterogeneous and include gastro-oesophageal reflux disease, gastroparesis, small intestinal bacterial overgrowth, intestinal pseudo-obstruction, malabsorption and the requirement for total parenteral nutrition. The abnormal gastrointestinal physiology that promotes the clinical manifestations of SSc gastrointestinal disease throughout the gastrointestinal tract are diverse and present a range of therapeutic targets. Furthermore, the armamentarium of medications and non-pharmacological interventions that can benefit affected patients has substantially expanded in the past 10 years, and research is increasingly focused in this area. Here, we review the details of the gastrointestinal complications in SSc, tie physiological abnormalities to clinical manifestations, detail the roles of standard and novel therapies and lay a foundation for future investigative work.

Gastric Electrical Stimulation: Role and Clinical Impact on Chronic Nausea and Vomiting

Gastric electrical stimulation (GES) is currently used as an alternative treatment for medically refractory gastroparesis. GES has been initially developed to accelerate gastric motility, in order to relieve the symptoms of the patients. Subsequent studies, unfortunately, failed to demonstrate the acceleration of gastric emptying using high-frequency stimulation - low energy stimulation although the technique has shown a clinical impact with a reduction of nausea and vomiting for patients with gastroparesis. The present review details the clinical efficacy of GES in gastroparesis as well as its putative mechanisms of action.

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.

Artificial Neural Network-Based Automatic Detection of Food Intake for Neuromodulation in Treating Obesity and Diabetes

PURPOSE

Neuromodulation, such as vagal nerve stimulation and intestinal electrical stimulation, has been introduced for the treatment of obesity and diabetes. Ideally, neuromodulation should be applied automatically after food intake. The purpose of this study was to develop a method of automatic food intake detection through dynamic analysis of heart rate variability (HRV).

MATERIALS AND METHODS

Two experiments were conducted: (1) a small sample series with a standard test meal and (2) a large sample series with varying meal size. Electrocardiograms (ECGs) were collected in the fasting and postprandial states. Each ECG was processed to compute the HRV. For each HRV segment, time- and frequency-domain features were derived and used as inputs to train and test an artificial neural network (ANN). The ANN was trained and tested with different cross-validation methods.

RESULTS

The highest classification accuracy reached with leave-one-subject-out-leave-one-sample-out cross-validation was 0.93 in experiment 1 and 0.88 in experiment 2. Retraining the ANN on recordings of a subject drastically increased the achieved accuracy for that subject to values of 0.995 and 0.95 in experiments 1 and 2, respectively.

CONCLUSIONS

Automatic food intake detection by ANNs, using features from the HRV, is feasible and may have a great potential for neuromodulation-based treatments of meal-related disorders.

Nausea and Vomiting in 2021: A Comprehensive Update

GOAL

A comprehensive review of treatments for nausea and vomiting (N/V).

BACKGROUND

N/V are common symptoms encountered in medicine. While most cases of acute N/V related to a specific cause can be straightforward to manage, other cases of acute N/V such as chemotherapy-induced N/V and especially chronic unexplained N/V can be difficult to control, leading to a significant decline in the patient's quality of life and increased cost of medical care from repeated hospitalizations.

STUDY

Traditional management has relied on pharmacotherapy which may be inadequate in a certain proportion of these patients. Many of the medications used in the management of N/V have significant side effect profiles making the need for new and improved interventions of great importance.

RESULTS

This review covers a broad review of the pathophysiology of N/V, pharmacotherapy, including safety concerns and controversies with established pharmaceuticals, newer immunotherapies, bioelectrical neuromodulation (including gastric electrical stimulation), behavioral and surgical therapies, and complementary medicine.

CONCLUSION

On the basis of emerging understandings of the pathophysiology of N/V, improved therapies are becoming available.

Gastric Electrical Stimulation for Treatment of Refractory Gastroparesis: the Current Approach to Management

Purpose of Review

Gastroparesis is one of the more challenging entities in the landscape of gastroenterology, posing difficulties for both patients and physicians with regard to effective management and therapies. In this article, we reviewed various gastroparesis treatment options, with an emphasis on gastric electrical stimulation (GES).

Recent Findings

GES has demonstrated a significant reduction of cardinal symptoms in refractory gastroparetic patients, particularly nausea and vomiting, across multiple studies. However, GES has not been shown to conclusively decrease gastric emptying time in these patients. Such finding has led the investigators to analyze the impact of combining GES with pyloroplasty. While this treatment pathway is nascent, its results thus far reveal an amplified improvement of gastroparesis symptomatology in addition to significant reduction of gastric transit, compared to GES by itself.

Summary

Limited treatment choices are available for refractory gastroparesis. Combining GES with pyloroplasty holds promise but requires further assessment in large-scale trials to fully evaluate the risks and benefits.

Noninvasive vagal nerve stimulation for gastroenterology pain disorders

Abdominal pain continues to be a major challenge and unmet need in clinical practice. Normalization of bidirectional gut-brain signaling has generated much interest as a therapeutic approach to treat chronic abdominal pain. Vagal nerve stimulation (VNS) is emerging as a potential non-pharmacologic strategy for the treatment of abdominal pain. In this review paper, we will summarize the etiologies of chronic pain in gastrointestinal disorders and discuss the rational for VNS as a therapeutic approach to chronic abdominal pain, with particular emphasis in the gammaCore stimulator which allows for noninvasive VNS.

Absorbable antibacterial envelope in the surgical management of Twiddler's syndrome in a patient with gastric electric stimulator: a case report

Gastroparesis is a chronic gastric motility disorder characterized by delayed gastric emptying and a multitude of troublesome symptoms, including chronic nausea, vomiting, abdominal pain, malnutrition, and dehydration. Whereas initial management of the gastroparesis is conservative, patient with refractory gastroparesis may benefit from surgical therapy, including gastric electric stimulator (GES) device implantation. Twiddler’s syndrome is a challenging condition well described in the cardiac literature that is characterized by the instability, displacement, leads twisting and resulting malfunction of an implanted device, believed to be due to manipulation (twiddling) by the patient. The condition is not specifically characterized in the GES literature; however, evidence suggest the incidence of the Twiddler’s syndrome is reaching up to 9% of the patients with GES. In the current report we present a case of surgical management of the recurrent Twiddler’s syndrome in a patient with a GES device with novel non-FDA approved use of the TYRX^™ Absorbable Antibacterial Envelope for the device stabilization. Use of the TYRX^™ enveloped provided additional anchoring points of fixation, resulting in the successful resolution of the device instability and the Twiddler’s syndrome with and ongoing follow up of up to 8 months. This report adds to the armamentarium of surgical management of this uncommon and difficult problem.

Gastric Electrical Stimulation Has an Effect on Gastric Interstitial cells of Cajal (ICC) That is Associated With Mast Cells

Introduction

Gastric electrical stimulation (GES) is an emerging therapy for gastric motility disorders, showing improvement of gastroparesis related symptoms in previous studies. Interstitial cells of Cajal (ICC) and mast cells have been shown to have a relevant role in gastroparesis pathogenesis. However, the exact effects of GES in those cells is relatively unknown.

Methods

Full thickness biopsies (FTBx) of 20 patients with refractory gastroparesis were obtained at the time of GES placement and repeated when the device was exchanged (mean of 22.5 months between biopsies). A patient-reported outcomes survey was obtained during each office visit during this period. All biopsies were stained with cluster of differentiation 117 (CD117), S100, and mast cell tryptase antibodies and were analyzed.

Results

Half of the patients had a significant increase of ICC during the repeated biopsy compared with baseline (p=0.01) and the other half had significant decrease in ICC levels (p=0.006) but there was no noticeable difference in mast cells counts at baseline between groups. Mast cells analysis was performed in two different groups depending on ICC change from the baseline biopsy (CD117 increase vs CD117 decrease). There was only a significant increase of mast cells count within the CD117 worsened ICC group (p=0.007).

Conclusion

No significant increase in the number of mast cells count seen in patients who received a GES may indicate an improvement in overall inflammation in patients with refractory gastroparesis after GES placement.

Ingestible transiently anchoring electronics for microstimulation and conductive signaling

Ingestible electronic devices enable noninvasive evaluation and diagnosis of pathologies in the gastrointestinal (GI) tract but generally cannot therapeutically interact with the tissue wall. Here, we report the development of an orally administered electrical stimulation device characterized in ex vivo human tissue and in in vivo swine models, which transiently anchored itself to the stomach by autonomously inserting electrically conductive, hooked probes. The probes provided stimulation to the tissue via timed electrical pulses that could be used as a treatment for gastric motility disorders. To demonstrate interaction with stomach muscle tissue, we used the electrical stimulation to induce acute muscular contractions. Pulses conductively signaled the probes' successful anchoring and detachment events to a parenterally placed device. The ability to anchor into and electrically interact with targeted GI tissues controlled by the enteric nervous system introduces opportunities to treat a multitude of associated pathologies.

Transcutaneous Neuromodulation at ST36 (Zusanli) is More Effective than Transcutaneous Tibial Nerve Stimulation in Treating Constipation

BACKGROUND AND GOALS

Combined transcutaneous neuromodulation (TN) at acupoint ST36 (Zusanli) and TN at the posterior tibial nerve (PTN) has been reported effective in treating functional constipation. This study was designed to compare the effectiveness of TN between these 2 points.

MATERIALS AND METHODS

Eighteen functional constipation patients (M/F: 9/9) were recruited to participate in a cross-over study with a 2-week TN at ST36 and a 2-week TN at PTN. A bowel movement diary, and the questionnaires of Patient Assessment of Constipation Symptom (PAC-SYM) and Constipation Quality of Life (PAC-QoL) were completed; anorectal manometry and spectral analysis of heart rate variability for assessing the autonomic function were performed.

RESULTS

(1) Both TN at ST36 and TN at PTN improved constipation-related symptoms (PAC-SYM scores on pre-TN vs. post-TN: 1.4±0.1 vs. 0.6±0.1 for ST36, 1.4±0.1 vs. 0.9±0.1 for PTN, both P≤0.001). (2) TN at ST36, but not TN at PTN, increased the number of weekly spontaneous bowel movements (0.9±0.2 pre-TN vs. 3.5±0.7 post-TN, P<0.001) and decreased the total PAC-QoL score. TN at ST36 was more potent than TN at PTN in improving the PAC-SYM score (decrement 0.8±0.1 vs. 0.5±0.1, P<0.05). (3) TN at ST36 rather than TN at PTN resulted in a reduction in sensation thresholds, including rectal distention for urge (134.1±14.3 mL pre-TN vs. 85.6±6.5 mL post-TN, P<0.01) and maximum tolerance (P<0.05). (4) Both TN at ST36 and TN at PTN significantly increased vagal activity and decreased sympathetic activity (P<0.05).

CONCLUSIONS

TN at ST36 is more potent than TN at PTN in treating constipation and improving constipation-related symptoms and rectal sensation.

Effectiveness of gastric electrical stimulation in gastroparesis: Results from a large prospectively collected database of national gastroparesis registries

BACKGROUND

Gastric electrical stimulation (GES) for treating gastroparesis symptoms is controversial.

METHODS

We studied 319 idiopathic or diabetic gastroparesis symptom patients from the Gastroparesis Clinical Research Consortium (GpCRC) observational studies: 238 without GES and 81 with GES. We assessed the effects of GES using change in GCSI total score and nausea/vomiting subscales between baseline and 48 weeks. We used propensity score methods to control for imbalances in patient characteristics between comparison groups.

KEY RESULTS

GES patients were clinically worse (40% severe vs. 18% for non-GES; P < .001); worse PAGI-QOL (2.2. vs. 2.6; P = .003); and worse GCSI total scores (3.5 vs. 2.8; P < .001). We observed improvements in 48-week GCSI total scores for GES vs. non-GES: improvement by ≥ 1-point (RR = 1.63; 95% CI = (1.14, 2.33); P = .01) and change from enrollment (difference = -0.5 (-0.8, -0.3); P < .001). When adjusting for patient characteristics, symptom scores were smaller and not statistically significant: improvement by ≥ 1-point (RR = 1.29 (0.88, 1.90); P = .20) and change from the enrollment (difference = -0.3 (-0.6, 0.0); P = .07). Of the individual items, the nausea improved by ≥ 1 point (RR = 1.31 (1.03, 1.67); P = .04). Patients with GCSI score ≥ 3.0 tended to improve more than those with score < 3.0. (Adjusted P = 0.02).

CONCLUSIONS AND INFERENCES

This multicenter study of gastroparesis patients found significant improvements in gastroparesis symptoms among GES patients. Accounting for imbalances in patient characteristics, only nausea remained significant. Patients with greater symptoms at baseline improved more after GES. A much larger sample of patients is needed to fully evaluate symptomatic responses and to identify patients likely to respond to GES.

Systematic review on gastric electrical stimulation in obesity treatment

Introduction: Obesity is a very common public health problem worldwide. However, there is a lack of effective therapies. Only a small portion of patients with morbid obesity are accepting bariatric surgery as the last option due to the risks associated with invasive therapy. Areas covered: In this paper, we review an emerging weight loss treatment: gastric electrical stimulation (GES). The feasibility of GES as a potential therapy for obesity is introduced. Methodologies and parameters of GES are presented. Several GES methods for treating obesity and their effects on food intake and body weight are presented. Possible mechanisms involved in the anti-obesity effect of GES are discussed. Finally, our comments on the potential of GES for obesity and expectations for future development of the GES therapy are provided. The PubMed central database was searched from inception to May 2019. The literature search used the following terms: 'Gastric electrical stimulation' combined with 'obesity' and 'Implantable gastric stimulation' and 'pharmaceutical therapy' and 'bariatric surgery'. Expert opinion: There is a potential to use GES for treating obesity. However, more efforts are needed to develop appropriate stimulation devices and to design an adequate therapy for treating obesity in humans.

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.

Vagal Nerve Stimulation for Glycemic Control in a Rodent Model of Type 2 Diabetes

BACKGROUND

Vagal nerve stimulation (VNS) has been reported to reduce body weight and improve sympathovagal imbalance in both basic and clinical studies. Its effects on glycemic control were however unclear. The aims of this study were to investigate the effects of VNS with various parameters on blood glucose and its possible mechanisms in rats.

METHODS

A hyperglycemic rodent model induced by glucagon was used initially to optimize the VNS parameters; then, a type 2 diabetic rodent model induced by high-fat diet combined with streptozotocin was used to validate the VNS method. The VNS electrodes were implanted at the dorsal subdiaphragmatic vagus; three subcutaneous electrodes were implanted at the chest area for recording electrocardiogram in rats induced by glucagon.

RESULTS

(1) VNS with short pulse width of 0.3 ms but not 3 ms reduced blood glucose during an oral glucose tolerance test (OGTT), with a 38.4% reduction at 15 min and 26.9% at 30 min (P < 0.05, vs. sham-VNS respectively). (2) VNS at low frequency of 5 Hz but not 14 Hz or 40 Hz reduced blood glucose during the OGTT (P < 0.05, vs. sham-VNS). (3) Intermittent VNS was more potent than continuous VNS (P < 0.01). (4) No difference was found between unilateral VNS and bilateral VNS. (5) VNS enhanced vagal activity (P = 0.005). (6) The hypoglycemic effect of VNS was blocked by glucagon-like peptide-1 (GLP-1) antagonist exendin-4.

CONCLUSIONS

VNS at 5 Hz reduces blood glucose in diabetic rats by enhancing vagal efferent activity and the release of GLP-1.

Per-oral Pyloromyotomy (POP) for Medically Refractory Gastroparesis: Short Term Results From the First 100 Patients at a High Volume Center

OBJECTIVE

For patients with gastroparesis, temporary pyloric disruption has been shown to improve symptoms and gastric emptying. Per-oral pyloromyotomy (POP) is an innovative endoscopic procedure to divide the pylorus from within a submucosal tunnel, as a corollary to surgical pyloromyotomy. Here we evaluate subjective and objective outcomes 12-weeks after POP at a high volume center.

METHODS

The first 100 consecutive patients undergoing POP were included, with procedure dates between January 2016 and October 2017. Patients were evaluated using the Gastroparesis Cardinal Symptom Index (GCSI), and 4-hour solid-phase scintigraphic gastric emptying studies (GES) prior to procedure and at 90 days post-POP RESULTS:: The study cohort was 85% female with a mean age of 45.0 ± 14.6 years. Gastroparesis etiologies were divided among idiopathic (56%), diabetic (21%), postsurgical (19%), and other in 4%. There were 67% of the patients who had previous endoscopic or surgical interventions for gastroparesis. Most POP procedures were performed in the operating room (97%) and were completed in an average of 33 minutes. Ten patients incurred complications (10%), which included 1 diagnostic laparoscopy and 2 cases of gastrointestinal bleeding. Overall GCSI improved from a preoperative mean of 3.82 ± 0.86 to 2.54 ± 1.2 (P < 0.001). The improvement in each GCSI subscore was also highly statistically significant. Among the patients with postoperative GES available, 78% had objectively better 4-hour emptying with a mean improvement in retention by 23.6% (P < 0.001). This included 57% of patients with normal gastric emptying post-POP.

CONCLUSION

For patients with medically refractory gastroparesis, POP results in both subjective and objective improvement in the majority of patients. Prior intervention does not obviate POP as a therapeutic option. POP should be included along the treatment algorithm for patients with gastroparesis as an organ-sparing procedure.

Ameliorating effects of optimized gastric electrical stimulation and mechanisms involving nerve growth factor and opioids in a rodent model of gastric hypersensitivity

BACKGROUND

Gastric electrical stimulation (GES) has been applied to treat gastric motility disorders for decades. This study was designed to investigate the effects and mechanisms of GES for visceral hypersensitivity in a rodent model of functional dyspepsia (FD).

METHODS

Male Sprague-Dawley rat pups at 10-days old received 0.1% iodoacetamide (IA) daily for 6 days. The experiments were performed when the rats reached 8-11 weeks of age, and visceral hypersensitivity was established. Then, GES parameters were optimized and the chronic effects of GES on gastric hypersensitivity were assessed by electromyogram (EMG). Naloxone (3 mg/kg), D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP, 1 mg/kg), and anti-NGF (16 μg/kg) were individually intraperitoneally injected to investigate opioid and nerve growth factor (NGF) mechanisms. Tissues were analyzed for NGF expression.

KEY RESULTS

In the IA-treated rats, the visceromotor response to gastric distension was significantly increased, and both acute GES with optimized stimulation parameters (0.25 seconds on, 0.25 seconds off, 100 Hz, 0.25 ms, 6 mA) and chronic GES (7 days, 2 hours/day) normalized gastric hypersensitivity. The inhibitory effect of GES on gastric hypersensitivity was blocked by naloxone and CTOP. Anti-NGF normalized EMG responses in IA-treated rats. The expressions of NGF in the tissues of IA-treated rats were dramatically increased, and these increases were suppressed with GES.

CONCLUSIONS AND INFERENCES

GES with optimized parameters improves gastric hypersensitivity induced by neonatal treatment of IA mediated peripherally by suppressing NGF and via the opioid mechanism involving the µ receptor. GES as a potential therapy for treating visceral pain may be explored in clinical studies.

A Formal Approach for Scalable Simulation of Gastric ICC Electrophysiology

OBJECTIVE

Efficient and accurate organ models are crucial for closed-loop validation of implantable medical devices. This paper investigates bio-electric slow wave modeling of the stomach, so that gastric electrical stimulator (GES) can be validated and verified prior to implantation. In particular, we consider high-fidelity, scalable, and efficient modeling of the pacemaker, Interstitial cells of Cajal (ICC), based on the formal hybrid input output automata (HIOA) framework.

METHODS

Our work is founded in formal methods, a collection of mathematically sound techniques originating in computer science for the design and validation of safety-critical systems. We modeled each ICC cell using an HIOA. We also introduce an HIOA path model to capture the electrical propagation delay between cells in a network. The resultant network of ICC cells can simulate normal and diseased action potential propagation patterns, making it useful for device validation.

RESULTS

The simulated slow wave of a single ICC cell had high correlation ( ≈ 0.9) with the corresponding biophysical models.

CONCLUSIONS

The proposed model is able to simulate the slow wave activity of a network of ICC cells with high-fidelity for device validation.

SIGNIFICANCE

The proposed HIOA model is significantly more efficient than the corresponding biophysical models, scales to larger networks of ICC cells, and is capable of simulating varying propagation patterns. This has the potential to enable verification and validation of implantable GESs in closed-loop with gastrointestinal models in the future.

Wisconsin's Enterra Therapy Experience: A multi-institutional review of gastric electrical stimulation for medically refractory gastroparesis

BACKGROUND

Gastric electrical stimulation is a treatment for symptoms of diabetic or idiopathic gastroparesis refractory to medical management. We sought to evaluate the outcomes of gastric electrical stimulation in the state of Wisconsin during a more than 10-year period.

METHODS

Data were collected prospectively from patients undergoing implantation of the gastric electrical stimulation to initiate gastric electrical stimulation therapy at two Wisconsin institutions from 2005-2017. The Gastroparesis Cardinal Symptom Index was administered during clinical encounters and over the phone preoperatively and postoperatively.

RESULTS

A total of 119 patients received gastric electrical stimulation therapy (64 diabetic and 55 idiopathic). All devices were placed laparoscopically. Mean follow-up was 34.1 ± 27.2 months in diabetic and 44.7 ± 26.2 months in idiopathic patients. A total of 18 patients died during the study interval (15.1%). No mortalities were device-related. Diabetics had the greatest rate of mortality (25%; mean interval of 17 ± 3 months post implantation). GCSI scores improved, and prokinetic and narcotic medication use decreased significantly at ≥1 year. Satisfaction scores were high.

CONCLUSION

Gastric electrical stimulation therapy led to the improvement of symptoms of gastroparesis and a better quality of life. Patients were able to decrease the use of prokinetic and narcotic medications and achieve long-term satisfaction. Diabetic patients who develop symptomatic gastroparesis have a high mortality rate over time.

Proof of concept: short-term non-invasive cervical vagus nerve stimulation in patients with drug-refractory gastroparesis

BACKGROUND

Gastric electric stimulation (GES) is a treatment approach to refractory gastroparesis, possibly acting centrally via afferent vagus nerve stimulation (VNS). Non-invasive VNS (nVNS) is a potential alternative to GES that could eliminate the safety risks of or identify likely responders to implantable neurostimulators.

OBJECTIVE

This open-label proof-of-concept study assessed the effects of nVNS in patients with severe drug-refractory gastroparesis.

METHODS

Patients used the Gastroparesis Cardinal Symptom Index (GCSI) to grade symptoms in diaries daily for 2 weeks before treatment (baseline) and during ≥3 weeks of nVNS therapy. Adverse events (AEs) were also diarised. Treatment was self-administered using an nVNS device (gammaCore, electroCore) and consisted of 120 s stimulations to the vagus nerve in the neck (two stimulations to each side three times daily during weeks 1 and 2; three stimulations to each side three times daily during week 3 and beyond). Response was defined as a ≥1 point decrease from baseline in GCSI score.

RESULTS

Thirty-five patients enrolled; 23 were compliant with study procedures and were included in the analysis; 7 continued treatment beyond 3 weeks. Response rates were 35% (8/23) at 3 weeks and 43% (10/23) for the duration of therapy (3-6 weeks). For the entire cohort and the 10 responders, improvements from baseline were noted for mean total GCSI and GCSI subscale scores (nausea/vomiting, postprandial fullness/early satiety, bloating). No serious AEs were reported.

CONCLUSIONS

These preliminary results provide a signal that nVNS may be useful for treating refractory gastroparesis. Larger controlled studies are warranted.

Gastric neuromuscular histology in patients with refractory gastroparesis: Relationships to etiology, gastric emptying, and response to gastric electric stimulation

BACKGROUND

The aims of this study were to describe the histology in gastroparesis, specifically to relate histopathology to etiology of gastroparesis (idiopathic and diabetic gastroparesis), gastric emptying, and clinical response to gastric electric stimulation.

METHODS

Full thickness gastric body sections obtained during insertion of gastric stimulator in gastroparetics were stained with Hematoxylin & Eosin, Masson Trichrome and immunohistochemical stains for Neuron-Specific Enolase and c-Kit.

KEY RESULTS

In all, 145 gastroparetics (71 diabetics, 71 idiopathic, 2 post-surgical, and 1 chronic intestinal pseudo-obstruction) had full thickness gastric body biopsies. A lymphocytic infiltrate was seen in the intermyenteric plexus in 22 diabetic and 23 idiopathic gastroparesis patients. Fibrosis was present in the inner circular layer in 13 diabetic and 15 idiopathics and in the outer longitudinal layer in 46 diabetic and 51 idiopathics. Diabetic gastroparesis had less ganglion cells (3.27±1.82 vs 4.81±2.81/hpf; P<.01) and less ganglia (0.90±0.44 vs 1.10±0.50/hpf; P=.01) than idiopathic gastroparesis. Interstitial cells of Cajal (ICC) count was slightly lower in the inner circular layer in diabetic than idiopathics (2.77±1.47 vs 3.18±1.34/hpf; P=.08). Delayed gastric emptying was associated with reduced ICCs in the myenteric plexus. Global therapeutic response to gastric electric stimulation was inversely related to ganglia/hpf (R=-.22; P=.008). In diabetics, improvements in nausea, vomiting, and abdominal pain were inversely related to fibrosis.

CONCLUSION AND INFERENCES

Histologic assessment of full thickness gastric biopsy specimens allows correlation of histopathology to the gastroparesis disease process, its etiology, gastric emptying, and response to gastric electric stimulation treatment.

Laparoscopic treatment of gastroparesis: a single center experience

BACKGROUND

Gastroparesis (GP) is a chronic disorder of gastric motility with delayed gastric emptying. Gastric electrical stimulator (GES) implantation and Roux-en-Y gastric bypass (RYGB) are surgical options for medically refractory GP.

OBJECTIVE

Evaluate operational outcomes and symptom improvement of patients with diabetic (DM) and idiopathic (IP) GP.

SETTING

University Hospital, United States.

METHODS

A retrospective chart review was performed of all patients who underwent surgical treatment of GP from February 2003 to December 2014. Subgroup analysis was performed based on etiology of GP (DM versus IP) and procedure received (GES versus RYGB). Postoperative outcomes and postoperative symptom improvements were compared between groups.

RESULTS

Of 93 patients, 47 (50.5%) had IP and 46 (49.5%) had DM. The majority underwent GES implantation (83.8%, n = 78), and 15 patients (16%) underwent RYGB. There were significant differences in hospital stay (2 versus 3 days) and reoperation rate (30% versus 7%) between IP and DM. Operation time, complication rate, and 30-day readmission rate were similar in both groups. DM patients significantly improved GP-related complaints compared with preoperatively. IP patients also improved nausea and vomiting and had no change in abdominal pain between pre- and postoperative period. GES showed significant improvement of nausea, vomiting, and abdominal pain. RYGB showed improvement of nausea, but not vomiting or abdominal pain.

CONCLUSIONS

Surgery is a feasible intervention for GP for both DM and IP patients; however, based on the data presented in this manuscript and the current literature, the use of gastric bypass as an effective treatment modality for patients with intractable GP remains highly controversial. Care must be taken for IP patients in the postoperative period due to high incidence of reoperation. Although both procedures offer some degree of symptomatic improvement, GES seems to provide improvement of more GP symptoms. However, there is no significant difference in the need for postoperative medications regardless of the procedure used.

Effectiveness and feasibility of robotic gastric neurostimulator placement in patients with refractory gastroparesis

Gastric neurostimulation (GNS) with Enterra^® therapy device (Medtronic, Minneapolis, MN) appears as the last resort for patients with refractory gastroparesis. Currently, the device has Humanitarian Use status by Food and Drug Administration, thereby requiring further investigation. We aim to describe its feasibility and clinical outcomes using robotic technique. From June 2014 to September 2016, 15 consecutive patients underwent robotic insertion of Enterra^® device. Patient demographics, comorbidities, and clinical outcomes including mortality, length of stay, readmission rates, reoperation and complications were retrospectively collected. Patients were also assessed based on a validated 14-point questionnaire regarding satisfaction with the operation, quality of life and symptomatic relief. Mean age was 41.6 years ± 13.8 and there were 11 females (73.3%). No mortality was reported. The annual hospital admissions were reduced after GNS (2.5 ± 4.1 vs. 3.6 ± 4.4, p = 0.004). The frequency of bloating (p = 0.029) and severity of emesis (p = 0.038), early satiety (p = 0.042) and bloating (p = 0.031) were reduced after GNS. The severity and frequency total scores were also improved after GNS (12.6 ± 1.4 vs. 18.1 ± 2.7, p = 0.008 and 12.9 ± 2.2 vs. 16.1 ± 1.1, p = 0.016, respectively). This is the first report describing the clinical experience with robotic insertion of GNS device. This approach is safe and feasible and seems to have similar long-term outcomes as laparoscopic technique. Potential advantages to robotic technique include enhanced dexterity and suturing of the device within gastric wall. Further experience with large prospective studies and randomized clinical trials may be warranted.

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.

Some Non-FDA Approved Uses for Neuromodulation in Treating Autonomic Nervous System Disorders: A Discussion of the Preliminary Support

INTRODUCTION

Neuromodulation, including cavernous nerve stimulation, gastric electrical stimulation, deep brain stimulation, and vagus nerve stimulation, has been used with success in treating several functional disease conditions. The FDA has approved the use of neuromodulation for a few indications. We discuss in our review article the evidence of using neuromodulation for treating some important disorders involving the autonomic nervous system that are not currently FDA approved.

METHODS

This was a review article that included a systematic online web search for human clinical studies testing the efficacy of neuromodulation in treating erectile dysfunction, gastroparesis, gastroesophageal reflux disease, obesity, asthma, and heart failure. Our review includes all feasibility studies, nonrandomized clinical trials, and randomized controlled trials.

RESULTS

Our systematic literature search found 3, 4, 5, 4, 1, and 4 clinical studies relating to erectile dysfunction, gastroparesis, gastroesophageal reflux disease, obesity, asthma, and heart failure, respectively.

CONCLUSION

This review article shows preliminary support based on clinical studies that neuromodulation can be of benefit for patients with important autonomic nervous system disease conditions that are not currently approved by the FDA. All of these investigational uses are encouraging; further studies are necessary and warranted for all indications discussed in this review before achieving FDA approval.

Functional Nausea in Children

Chronic nausea is a highly prevalent, bothersome, and difficult-to-treat symptom among adolescents. When chronic nausea presents as the predominant symptom and is not associated with any underlying disease, it may be considered a functional gastrointestinal disorder and named "functional nausea." The clinical features of functional nausea and its association with comorbid conditions provide clues to the underlying pathophysiological mechanisms. These may include gastrointestinal motor and sensory disturbances, autonomic imbalance, altered central nervous system pathways, or a combination of these. This review summarizes the current knowledge on mechanisms and treatment strategies for chronic, functional nausea in children.

Gastric Electric Stimulation for Refractory Gastroparesis: A Prospective Analysis of 151 Patients at a Single Center

BACKGROUND

Gastric electric stimulation (GES) is used to treat patients with refractory gastroparesis symptoms. However, the effectiveness of GES in clinical practice and the effect of GES on specific symptoms of gastroparesis are not well delineated.

AIMS

To determine the effectiveness of GES for treatment for refractory symptoms of gastroparesis, the improvement in specific symptoms of gastroparesis, and clinical factors impacting on outcome.

METHODS

Enterra GES was used to treat refractory gastroparesis symptoms. Patients filled out a symptom severity questionnaire (PAGI-SYM) prior to insertion. At each follow-up visit, the patient filled out PAGI-SYM and assessed their therapeutic response using the Clinical Patient Grading Assessment Scale (CPGAS).

RESULTS

One hundred and fifty-one patients (120 females) with refractory gastroparesis (72 diabetic, 73 idiopathic, 6 other) underwent GES. Of the 138 with follow-up (1.4 ± 1.0 years), the average CPGAS was 2.4 ± 0.3 (SEM): 104 patients (75 %) improved (CPGAS > 0) and 34 (25 %) did not (CPGAS ≤ 0). Sixty patients (43 %) were at least moderately improved (CPGAS score ≥4). Clinical improvement was seen in both diabetic and idiopathic patients with the CPGAS in diabetic patients (3.5 ± 0.3) higher in idiopathic patients (1.5 ± 0.5; p < 0.05). Symptoms significantly improving the most included nausea, loss of appetite, and early satiety. Vomiting improved in both diabetic and idiopathic patients although the diabetic subgroup experienced a significantly greater reduction in vomiting than the idiopathic subgroup.

CONCLUSIONS

In this cohort of patients with refractory gastroparesis, GES improved symptoms in 75 % of patients with 43 % being at least moderately improved. Response in diabetics was better than in nondiabetic patients. Nausea, loss of appetite, and early satiety responded the best.

Current advances in treatment of gastroparesis

INTRODUCTION

Gastroparesis is a syndrome defined by delayed gastric emptying in the absence of mechanical obstruction. Gastroparesis has significant symptomatology and negative impacts on the patient's quality of life.

AREAS COVERED

This article reviews current treatment options for gastroparesis, recent advances in treatment and future directions that treatment may head. Current options are broadly divided into prokinetics and symptom modulators. Within each group, current modalities as well as recent advances are discussed according to agent mechanism of action. Lastly, findings regarding the cellular pathophysiology involved in gastroparesis will be briefly reviewed along with their implications for future treatments.

EXPERT OPINION

The numerous motor functions and neural inputs that control gastric motility are complex and not fully understood. Our lack of understanding of its pathophysiology has led to treatment options which are empirical, palliative and often ineffective. Newly intensified interest in the cellular pathophysiology behind gastroparesis provides promise for a new era of treatments. Identification of common cellular changes in gastroparesis has provided targets for treatment that may allow us to one day better treat the symptoms of gastroparesis related to its underlying pathophysiology. This is the future of gastroparesis therapy.

Neurostimulation of the gastrointestinal tract: review of recent developments

OBJECTIVE

Neurostimulation is one manifestation of neuromodulation of the gastrointestinal (GI) tract. This manuscript reviews the history of neurostimulation of the GI tract with emphasis on current methods of stimulation.

MATERIALS AND METHODS

A review was completed of the current research on GI neurostimulation methods with an emphasis on their clinical applications.

RESULTS

Upper GI disorders can be modulated with both temporary (placed endoscopically or surgically) or permanent (placed surgically) gastric electrical stimulation (GES) devices. The current GI neurostimulation of stomach (GES) devices have been used in both children and adults, and some patients have been followed in excess of 15 years with good long-term results. Similar GES devices also have been used for a variety of lower GI disorders, including constipation and fecal incontinence, for a number of years.

CONCLUSIONS

GI neurostimulation, as a type of neuromodulation, has been demonstrated to function at several locations in the GI tract for a variety of disorders. The future of neurostimulation in the GI tract will likely be influenced by a better understanding of pathophysiology as well as the development of new techniques and devices for neuromodulation.

Effectiveness of gastric neurostimulation in patients with gastroparesis

BACKGROUND

Patients with gastroparesis have significantly delayed gastric emptying because of impaired nerve function. Gastric neurostimulation from Enterra Therapy provides electrical pulses to the stomach tissue that promotes stimulation of stomach smooth muscle, thereby enhancing gastric emptying. This study evaluates the effectiveness of Enterra Therapy (Medtronic, Minneapolis, Minnesota) in reducing symptoms and improving the quality of life of patients with drug-refractory gastroparesis.

MATERIAL AND METHODS

In this study 25 patients underwent minimally invasive, laparoscopic placement of the Enterra Therapy device. Patients were asked to rank their severity of symptoms and quality of life retrospectively by completing the Gastrointestinal Symptoms Rating Scale and Short Form 36 Health Survey with respect to their condition before and 6 months after initiation of Enterra Therapy.

RESULTS

Eighteen patients completed the surveys. Patients showed statistically significant improvement in their overall Gastrointestinal Symptoms Rating Scale scores and the mental health component of the Short Form 36 Health Survey.

DISCUSSION

Currently, Enterra Therapy has Humanitarian Use Device status, which means that more clinical evidence is needed to prove its effectiveness in gastroparesis. By showing that Enterra Therapy reduces symptoms of gastroparesis and improves patient quality of life, this study contributes to the increasing amount of data supporting its use and potential Food and Drug Administration approval.

Antiemesis effect and brain fMRI response of gastric electrical stimulation with different parameters in dogs

BACKGROUND

The aims of this study were to investigate the effect of gastric electrical stimulation (GES) with different parameters on emesis induced by apomorphine, and possible center mechanisms by brain functional magnetic resonance imaging (fMRI).

METHODS

Six dogs implanted with electrodes on gastric serosa were used in this study. Part 1: Apomorphine was injected in the control session and GES sessions. GESs with different parameters were applied in GES session. Gastric slow waves and emesis and behaviors suggestive of nausea were recorded in each session. Part 2: Each dog was anesthetized and given GESs with different parameters or sham stimulation for 15 min after baseline (5 min), respectively. The location of cerebral activation induced by GES was investigated by fMRI.

KEY RESULTS

Apomorphine induced emesis and behaviors suggestive of nausea, and gastric dysrhythmia. The emesis frequency in control session was 5.5 ± 0.99, and symptoms score was 22.17 ± 1.01. GES with short pulse and long pulse could not improve emesis and symptoms induced by apomorphine. The emesis frequency (4.5 ± 0.76 in short pulse and 6.33 ± 1.05 in long pulse) and symptoms scores had no significant difference compared to control session (each p > 0.05). GES with trains of short pulse reduced emesis time frequency (3.83 ± 0.7, p = 0.042 vs control) and symptoms score (p = 0.037 vs control) obviously. Brain fMRI showed that GES with short pulse and long pulse activated brain stem region, and trains of short pulse made amygdala and occipital lobe activation.

CONCLUSIONS & INFERENCES

Apomorphine induced emesis and gastric dysrhythmia. GES with trains of short pulses relieves emetic responses through activation of amygdala region.

Chronic idiopathic nausea

Chronic nausea is a prevalent but poorly described symptom in adolescents. It often co-occurs with other functional gastrointestinal disorders (FGIDs) but may also present in isolation. A multitude of triggers and complex neural pathways underlie the sensation of nausea. These include gastrointestinal and blood-borne insults, dysmotility, vestibular or central nervous system pathways, an aberrant autonomic nervous system, and psychosocial factors. Although clinical algorithms are lacking, diagnosis is typically made on the basis of a thorough clinical history and without extensive testing. Treatment is mainly empiric and may be directed at comorbid symptoms such as migraine, delayed gastric emptying, orthostatic intolerance, and visceral hypersensitivity. Chronic idiopathic nausea is an increasingly prevalent symptom that needs careful clinical assessment and individualized treatment plans.

Why does vomiting stop a migraine attack?

Migraine is commonly associated with nausea and vomiting, though, interestingly, vomiting has also been reported by some patients to be therapeutic, and may actually stop a migraine attack. In this review, we will first discuss the epidemiology of nausea and vomiting in migraine. Further, we will briefly review the connections between the enteric nervous system, the autonomic nervous system, and the central nervous system as they pertain to understanding the question of "Why does vomiting stop a migraine attack?"

Effects and mechanisms of gastric electrical stimulation on visceral pain in a rodent model of gastric hyperalgesia secondary to chemically induced mucosal ulceration

BACKGROUND

Gastric electrical stimulation (GES) has been suggested as a potential treatment for patients with gastric motility disorders. The aim of this study was to examine the effects and mechanisms of GES on visceral pain in awaken rats.

METHODS

Under anesthesia, acetic acid was injected into the submucosal layer of the stomach wall in Sprague-Dawley (SD) male rats. Each rat was chronically placed with an intragastric balloon and two pairs of electrodes on gastric serosa for GES and at the neck muscles for electromyography (EMG) recordings respectively. The study was composed of four experiments. Exp 1 was designed to determine optimal GES parameters in reducing EMG response to gastric distention (GD). Exp 2 was performed to investigate the effect of GES on gastric tone/accommodation. Exp 3 was to investigate if the opioid pathway was involved in the analgesic effects of GES. Exp 4 was to assess the effectiveness of GES on the spinal cord neurons (T9-T10) responding to GD.

KEY RESULTS

(i) Gastric electrical stimulation with a train on of 0.1 s and off of 0.4 s, 0.25 ms, 100 Hz, and 6 mA significantly reduced GD-induced EMG responses at GD 40, 60, and 80 mmHg. (ii) The inhibitory effects of GES on the GD-induced EMG responses were blocked by Naloxone. (iii) GES inhibited 90% of high-threshold (HT) spinal neurons in response to GD. However, GES with the same parameters only suppressed 36.3% low-threshold (LT) neuronal response to GD.

CONCLUSIONS & INFERENCES

Gastric electrical stimulation with optimal parameters inhibits visceral pain; the analgesic effect of GES on visceral pain is mediated via the endogenous opioid system and the suppression of spinal afferent neuronal activities.

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.

Evaluation and treatment of gastric stimulator failure in patients with gastroparesis

OBJECTIVE

This study evaluates treatment of gastroparesis patients refractory to gastric electrical stimulation (GES) therapy with surgical replacement of the entire GES system.

SUMMARY BACKGROUND DATA

Some patients who have symptomatic improvement with GES later develop recurrent symptoms. Some patients improve by simply altering pulse parameter settings. Others continue to have symptoms with maximized pulse parameters. For these patients, we have shown that surgical implantation of a new device and leads at a different gastric location will improve symptoms of gastroparesis.

METHODS

This study evaluates 15 patients with recurrent symptoms after initial GES therapy who subsequently received a second GES system. Positive response to GES replacement therapy is evaluated by symptoms scores for vomiting, nausea, epigastric pain, early satiety, and bloating using a modified Likert score system, 0 to 4.

RESULTS

Total symptom scores improved for 12 of 15 patients with GES replacement surgery. Total score for the replacement group decreased from 17.3 ± 1.6 to 13.6 ± 3.7 with a difference of 3.6 (P value = .017). This score is compared with that of the control group with a preoperative symptom score of 15.8 ± 3.6 and postoperative score of 12.3 ± 3.5 with a difference of 3.5 (P value = .011). The control group showed a 20.3% decrease in mean total symptoms score, whereas the study group showed a 22.5% decrease in mean with an absolute reduction of 2.2.

CONCLUSION

Reimplantation of a GES at a new gastric location should be considered a viable option for patients who have initially failed GES therapy for gastroparesis.

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.

Long-term effects of gastric stimulation on gastric electrical physiology

INTRODUCTION

This study evaluates the modeling of gastric electrophysiology tracings during long-term gastric electrical stimulation for gastroparesis. We hypothesized that serosal electrogastrogram may change over time representing gastric remodeling from gastric stimulation.

PATIENTS

Sixty-five patients with gastroparesis underwent placement of gastric stimulator for refractory symptoms. Mean age at initial stimulator placement was 44 years (range, 8-76), current mean age was 49, and the majority of the subjects were female (n = 51, 78 %). Only a minority had diabetes-induced gastroparesis (n = 16, 25 %); the remainder were either idiopathic or postsurgical.

METHODS

At the time of stimulator placement, electrogastrogram was performed after the gastric leads were placed but before stimulation was begun. Patients underwent continuous stimulation until pacer batteries depleted. At the time of replacement, before the new pacemaker was attached, electrogastrogram was again performed.

RESULTS

After a mean of 3.9 years of stimulation therapy, the mean of baseline frequency before stimulation therapy was 5.06 cycles/min and declined to 3.66 after replacement (p = 0.0000002). The mean amplitude was 0.33 mV before stimulation therapy and decreased to 0.31 mV (p = 0.73). The frequency/amplitude ratio was 38.4 before stimulation therapy and decreased to 21.9 (p = 0.001).

CONCLUSION

Long-term gastric electrical stimulation causes improvement in basal unstimulated gastric frequency to near normal.

Minimally invasive surgical approach for the treatment of gastroparesis

BACKGROUND

Gastroparesis is a chronic disorder resulting in decreased quality of life. The gastric electrical stimulator (GES) is an alternative to gastrectomy in patients with medically refractory gastroparesis. The aim of this study was to analyze the outcomes of patients treated with the gastric stimulator versus patients treated with laparoscopic subtotal or total gastrectomy.

METHODS

A retrospective chart review was performed of all patients who had surgical treatment of gastroparesis from January 2003 to January 2012. Postoperative outcomes were analyzed and symptoms were assessed with the Gastroparesis Cardinal Symptom Index (GCSI).

RESULTS

There were 103 patients: 72 patients (26 male/46 female) with a GES, implanted either with laparoscopy (n = 20) or mini-incision (n = 52), and 31 patients (9 male/22 female) who underwent laparoscopic subtotal (n = 27), total (n = 1), or completion gastrectomy (n = 3). Thirty-day morbidity rate (8.3% vs. 23%, p = 0.06) and in-hospital mortality rate (2.7% vs. 3%, p = 1.00) were similar for GES and gastrectomy. There were 19 failures (26%) in the group of GES patients; of these, 13 patients were switched to a subtotal gastrectomy for persistent symptoms (morbidity rate 7.7%, mortality 0). In total, 57% of patients were treated with GES while only 43% had final treatment with gastrectomy. Of the GES group, 63% rated their symptoms as improved versus 87% in the primary gastrectomy group (p = 0.02). The patients who were switched from GES to secondary laparoscopic gastrectomy had 100% symptom improvement. The median total GCSI score did not show a difference between the procedures (p = 0.12).

CONCLUSION

The gastric electrical stimulator is an effective treatment for medically refractory gastroparesis. Laparoscopic subtotal gastrectomy should also be considered as one of the primary surgical treatments for gastroparesis given the significantly higher rate of symptomatic improvement with acceptable morbidity and comparable mortality. Furthermore, the gastric stimulator patients who have no improvement of symptoms can be successfully treated by laparoscopic subtotal gastrectomy.