Association between changes in symptoms and gastric emptying in gastroparetic patients treated with gastric electrical stimulation

The Efficacy of Tradipitant in Patients With Diabetic and Idiopathic Gastroparesis in a Phase 3 Randomized Placebo-Controlled Clinical Trial

BACKGROUND

Neurokinin receptor 1 antagonists are effective in reducing nausea and vomiting in chemotherapy-induced emesis. We investigated the safety and efficacy of tradipitant, a neurokinin receptor 1 antagonist, in patients with idiopathic and diabetic gastroparesis.

METHODS

A total of 201 adults with gastroparesis were randomly assigned to oral tradipitant 85 mg (n = 102) or placebo (n = 99) twice daily for 12 weeks. Symptoms were assessed by a daily symptom dairy, Gastroparesis Cardinal Symptom Index scores, and other patient-reported questionnaires. Blood levels were monitored for an exposure-response analysis. The primary outcome was change from baseline to week 12 in average nausea severity, measured by daily symptom diary.

RESULTS

The intention-to-treat (ITT) population did not meet the prespecified primary endpoint at week 12 (difference in nausea severity change drug vs placebo; P = .741) or prespecified secondary endpoints. Post hoc analyses were performed to control for drug exposure, rescue medications, and baseline severity inflation. Subjects with high blood levels of tradipitant significantly improved average nausea severity beginning at early time points (weeks 2-4). In post hoc sensitivity analyses, tradipitant treatment demonstrated strengthened effects, with statistically significant improvements in nausea at week 12.

CONCLUSIONS

Although tradipitant did not reach significance in the ITT population, a pharmacokinetic exposure-response analysis demonstrated significant effects with adequate tradipitant exposure. When accounting for confounding factors such as baseline severity inflation and rescue medication, a statistically significant effect was also observed. These findings suggest that tradipitant has potential as a treatment for the symptom of nausea in gastroparesis. (ClincialTrials.gov, Number: NCT04028492).

Short-term outcomes of different modalities of pyloromyotomy versus gastric electrical stimulation in the treatment of gastroparesis: A systemic review and meta-analysis

BACKGROUND

The aim of this meta-analysis was to compare the short-term outcomes surrounding the efficacy and complication rate between different modalities of pyloromyotomy and gastric electrical stimulation (GES) in the treatment of gastroparesis.

METHODS

Comprehensive, computerized research was performed on PubMed, Embase, and the Cochrane Central Register of Controlled Trials. We additionally reviewed relevant articles, without any language limitations, published prior to April 15, 2020. Meta-analysis was conducted using RevMan 5.3 software.

RESULTS

Three studies totaling 196 participants who had received 4 interventions, including single per-oral pyloromyotomy (POP), double POP, laparoscopic pyloromyotomy, and GES, were eligible for analysis. Compared to single POP, double POP achieved a better clinical response with a pooled relative risk (RR) of 1.27 (95% confidence interval [CI], 1.01-1.60, P = .04), while laparoscopic pyloromyotomy and GES showed no difference with a pooled RR of 0.89 (95% CI, 0.74-1.08, P = .23) and 0.87 (95% CI, 0.73-1.04, P = .13), respectively. As for the recurrence and complication rates, only GES showed a borderline significance of recurrence in comparison to single POP (RR 2.17, 95% CI, 1.00-4.71, P = .05), while there were no differences in the remainder of the comparisons.

CONCLUSIONS

We conducted a detailed comparison of 3 modalities of pyloromyotomy and GES in the treatment of gastroparesis, with the results suggesting that double POP demonstrated better clinical success with similar recurrence and complication rates. In addition, GES may result in more recurrence amongst these interventions.

Efficacy of gastric electrical stimulation in intractable nausea and vomiting at 10 years: A retrospective analysis of prospectively collected data

BACKGROUND

Gastric electrical simulation has been shown to relieve nausea and vomiting in medically refractory patients. Efficacy of gastric electrical stimulation has been reported mostly in short-term studies, but none has evaluated its efficacy beyond 10 years after implantation.

METHODS

Patients implanted at our center for medically refractory severe and chronic nausea and/or vomiting were evaluated before and over 10 years after implantation using symptomatic scale and quality of life (GIQLI) score. Improvement was defined as a reduction of more than 50% in vomiting frequency.

KEY RESULTS

A total of 50 patients were implanted from January 1998 to December 2009. Among them, 7 were explanted due to a lack of efficacy and/or side effects, 2 died, and 4 were lost to follow-up. Mean follow-up was 10.5 ± 3.7 years. In intention-to-treat analysis, 27/50 (54%) patients reported an improvement. Beyond 10 years, an improvement in early satiety (3.05 vs 1.76, <0.001), bloating (2.51 vs 1.70, P = .012), nausea (2.46 vs 1.35, P = .001), and vomiting (3.35 vs 1.49 P < .001) scores were observed. Quality of life improved over 10 years (GIQLI score: 69.7 vs. 86.4, P = .005) and body mass index (BMI: 23.4 vs. 26.2 kg/m² ; P = .048).

CONCLUSIONS AND INFERENCES

Gastric electrical simulation is effective in the long-term in patients with medically refractory nausea and vomiting, with an efficacy of 54% at 10 years on an intention-to-treat analysis. Other long-term observational studies are warranted to confirm these results.

Status of Brain Imaging in Gastroparesis

The pathophysiology of nausea and vomiting in gastroparesis is complicated and multifaceted involving the collaboration of both the peripheral and central nervous systems. Most treatment strategies and studies performed in gastroparesis have focused largely on the peripheral effects of this disease, while our understanding of the central nervous system mechanisms of nausea in this entity is still evolving. The ability to view the brain with different neuroimaging techniques has enabled significant advances in our understanding of the central emetic reflex response. However, not enough studies have been performed to further explore the brain–gut mechanisms involved in nausea and vomiting in patients with gastroparesis. The purpose of this review article is to assess the current status of brain imaging and summarize the theories about our present understanding on the central mechanisms involved in nausea and vomiting (N/V) in patients with gastroparesis. Gaining a better understanding of the complex brain circuits involved in the pathogenesis of gastroparesis will allow for the development of better antiemetic prophylactic and treatment strategies.

Gastric Electrical Stimulation Reduces Refractory Vomiting in a Randomized Crossover Trial

BACKGROUND & AIMS

There have been conflicting results from trials of gastric electrical stimulation (GES) for treatment of refractory vomiting, associated or not with gastroparesis. We performed a large, multicenter, randomized, double-blind trial with crossover to study the efficacy of GES in patients with refractory vomiting, with or without gastroparesis.

METHODS

For 4 months, we assessed symptoms in 172 patients (66% women; mean age ± standard deviation, 45 ± 12 years; 133 with gastroparesis) with chronic (>12 months) of refractory vomiting (idiopathic, associated with a type 1 or 2 diabetes, or postsurgical). A GES device was implanted and left unactivated until patients were randomly assigned, in a double-blind manner, to groups that received 4 months of stimulation parameters (14 Hz, 5 mA, pulses of 330 μs) or no stimulation (control); 149 patients then crossed over to the other group for 4 months. Patients were examined at the end of each 4-month period (at 5 and 9 months after implantation). Primary endpoints were vomiting score, ranging from 0 (daily vomiting) to 4 (no vomiting), and the quality of life, assessed by the Gastrointestinal Quality of Life Index scoring system. Secondary endpoints were changes in other digestive symptoms, nutritional status, gastric emptying, and control of diabetes.

RESULTS

During both phases of the crossover study, vomiting scores were higher in the group with the device on (median score, 2) than the control group (median score, 1; P < .001), in diabetic and nondiabetic patients. Vomiting scores increased significantly when the device was ON in patients with delayed (P < .01) or normal gastric emptying (P = .05). Gastric emptying was not accelerated during the ON period compared with the OFF period. Having the GES turned on was not associated with increased quality of life.

CONCLUSIONS

In a randomized crossover study, we found that GES reduced the frequency of refractory vomiting in patients with and without diabetes, although it did not accelerate gastric emptying or increase of quality of life. Clinicaltrials.gov, Number: NCT00903799.

Gastric electrical stimulation: An emerging therapy for children with intractable gastroparesis

Management of gastroparesis remains challenging, particularly in pediatric patients. Supportive care and pharmacological therapies for symptoms remain the mainstay treatment. Although they are effective for mild and some moderately severe cases, often time they do not work for severe gastroparesis. There are a few prokinetics available, yet the use of these drugs is limited by a lack of persistent efficacy and/or safety concerns. Currently, the only modality for adult patients with severe intractable gastroparesis is surgery, e.g., pyloroplasty and partial gastrectomy, however, this option is generally considered too radical for a growing child. Novel therapeutic approaches, particularly those which are less invasive, are needed. This article explores gastric electrical stimulation (GES), a new therapy for gastroparesis. Unlike others, it neither needs medications nor gastrectomy; rather, it treats through the use of microelectrodes to deliver high-frequency low energy electric stimulation to the pacemaker area of the stomach. Thus, it is tolerated and safe in children. Like in adult patients, GES appears to work in releasing symptoms, improving nutrition, and enhancing the quality of life; it also helps wean off medications and eliminate many needs for hospitalization. Considering the transient nature of gastroparesis in children in many occasions, GES is considered a “bridging” therapy after failed medical interventions and before surgery.

The American neurogastroenterology and motility society gastroparesis cardinal symptom index-daily diary (ANMS GCSI-DD): Psychometric evaluation in patients with idiopathic or diabetic gastroparesis

BACKGROUND

The purpose of this study was to evaluate the measurement properties of the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index-Daily Diary, a patient-reported outcome instrument developed to meet US FDA recommendations for a symptom-based clinical trial endpoint in gastroparesis. The ANMS GCSI-DD assesses nausea, early satiety, postprandial fullness, and upper abdominal pain on a severity score from none (0) to very severe (4) and number of vomiting episodes during the past 24 hours. The composite score includes the first four symptoms, the core symptom score includes all five symptoms.

METHODS

Seventy-one patients diagnosed with idiopathic or diabetic gastroparesis were recruited for a four-week observational study. Patients completed the ANMS GCSI-DD at home between Baseline and Week 4. Statistical analyses included confirmatory factor analysis, item response theory analysis, internal consistency, test-retest reliability, and construct and known-groups validity.

KEY RESULTS

Unidimensionality for the composite and core symptom scores was supported, and items exhibited good fit. Internal consistency (Cronbach's alpha =0.85 and 0.83) and test-retest reliability were 0.89 and 0.88, for composite and core symptom scores, respectively. Convergent validity was supported by strong correlations with patient-reported and clinician measures. Baseline and Week 4 scores differed for three measures used to define disease severity status (P < 0.0001), supporting known-groups validity.

CONCLUSIONS & INFERENCES

The ANMS GCSI-DD has excellent reliability and validity, supporting its use to assess symptom-based endpoints in gastroparesis clinical studies. Further analyses will be conducted using clinical trial data to ascertain treatment responsiveness and define a responder.

The content validity of the ANMS GCSI-DD in patients with idiopathic or diabetic gastroparesis

BACKGROUND

The American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index-Daily Diary (ANMS GCSI-DD) was developed to meet Food and Drug Administration (FDA) recommendations for patient-reported outcome (PRO) endpoints in gastroparesis studies, including therapeutic trials. The current version of the ANMS GCSI-DD contains five items pertaining to nausea, early satiety, post-prandial fullness, upper abdominal pain, and vomiting. The specific aims of this study were to determine if the appropriate symptoms are included in the ANMS GCSI-DD and to assess the content validity in patients with idiopathic (IG) and diabetic gastroparesis (DG).

METHODS

Patients diagnosed with IG or DG were recruited by five clinical sites in the United States for a cross-sectional, qualitative study involving one-on-one in-person concept elicitation and cognitive debriefing interviews. Concept elicitation included open-ended questions to elicit patients' symptoms and impacts of gastroparesis, while cognitive debriefing was designed to assess the comprehensiveness of the ANMS GCSI-DD and clarity of the instructions, items, and response scales. The interviews were audio-recorded and transcribed. Transcripts were analyzed using a content analysis approach with ATLAS.ti.

RESULTS

Of 25 patients interviewed, 15 (60%) had IG and 10 (40%) DG. Mean age of the sample was 42.3 years (range: 20-70 years), and most patients were female (n = 19, 76%) and white (n = 19, 76%). During concept elicitation, patients endorsed the following signs and symptoms as relevant and important to their condition: early satiety (n = 25, 100%), post-prandial fullness (n = 25, 100%), nausea (n = 22, 88%), upper abdominal pain (n = 18, 72%), vomiting (n = 15, 60%), and bloating (n = 11, 44%). Many patients (n = 20, 80%) experienced day-to-day symptom change. During cognitive debriefing, patients confirmed the ANMS GCSI-DD content was comprehensive and reflective of their gastroparesis experience. Patients could easily select a response option and describe how they arrived at their answers. Overall, patients found the instrument's instructions, recall period, items, and response options clear and understandable.

CONCLUSIONS

The ANMS GCSI-DD was easily understood, found to contain the most important symptoms for patients with IG and DG, and no changes were recommended. Results support the content validity of the ANMS GCSI-DD for clinical trials and clinical care among IG or DG patients.

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.

Outcomes of surgical intervention for refractory gastroparesis: a systematic review

BACKGROUND

Gastroparesis (GP) is characterized by delayed gastric emptying with symptoms of nausea, vomiting, early satiety, postprandial fullness, and abdominal pain. Various surgical options exist to treat GP not responding to medical treatments (refractory GP), including gastric electric stimulation (GES), gastrectomy (GTx), and pyloric interventions (PI), whereas the outcomes of these procedures have been published; few comparison studies exist.

METHODS

PubMed literature review for articles from September 1988 to October 2017 was performed for prospective and retrospective analyses reporting >5 patients. Unweighted (per study) and weighted (per patient) overall improvement and improvement in symptoms of nausea, vomiting, and abdominal pain were calculated and compared for the different procedures.

RESULTS

Of 325 studies satisfying search criteria, 38 met the study criteria and were included for analysis. Total response to intervention, both weighted and unweighted, was greater with PIs compared to GES (P < 0.05). For unweighted symptom improvements, nausea improved more with PI than with GES (P < 0.05). GES improved vomiting more than epigastric pain (P < 0.05). For weighted symptom improvements, pyloric surgery and GTx improved vomiting compared to GES (P < 0.05).

CONCLUSIONS

Published outcomes of GES, pyloric surgery, and GTx for refractory GP are compared. Pyloromyotomy/pyloroplasty improves patient response greater than with GES. Weighing by number of studies, pyloric surgery improves nausea and abdominal pain greater than GES. For GES, vomiting is more likely to improve than abdominal pain. Weighing by number of patients, pyloric surgery and GTx improved vomiting compared to GES.

Pathological Findings of the Antral and Pyloric Smooth Muscle in Patients with Gastroparesis-Like Syndrome Compared to Gastroparesis: Similarities and Differences

BACKGROUND

Gastroparesis (GP)-like syndrome presents with the symptoms of GP but without delayed gastric emptying (GE). Whether GP-like syndrome is part of a spectrum of GP is not clear. This study aimed to compare the histopathological features of antral and pyloric smooth muscle tissue in GP and GP-like syndrome.

METHODS

Full-thickness antral and/or pyloric biopsies were obtained from 37 GP and 18 GP-like syndrome patients who underwent abdominal surgery to place a gastric electrical stimulator or jejunal feeding tube and/or pyloroplasty. The tissues were stained with H&E, C-Kit, and trichrome. Based on previous control data, an interstitial cells of Cajal (ICC) count of <10 per high power field in the antrum and/or pylorus was considered depletion. Baseline total symptom score (TSS) was recorded.

RESULTS

Twenty-four GP and 7 GP-like patients had pyloric biopsies. Pyloric ICC loss was observed in 20/24 (83.3%) GP and 2/7 (28.6%) GP-like patients (p < 0.01). Fibrosis was detected in the pyloric tissue of 20/24 (83.3%) GP and 2/7 (28.6%) GP-like patients who had pyloric trichrome staining (p < 0.01). Seventeen out of 24 (70.8%) GP patients with pyloric biopsies had concomitant pyloric ICC loss and fibrosis, while only one GP-like patient had ICC loss and simultaneous pyloric fibrosis. GP patients had a greater TSS compared to GP-like patients. In GP patients, those with pyloric ICC loss had a greater TSS compared to those with normal ICC. GP patients with pyloric fibrosis had a higher TSS compared to those without pyloric fibrosis.

CONCLUSIONS

Compared to GP-like patients, the pyloric histopathological findings of ICC loss and fibrosis are common in GP and predict a greater symptom score. These pathological findings might be considered as markers of "pyloric dysfunction" and explain delayed GE in GP.

Gastrointestinal Peptides During Chronic Gastric Electrical Stimulation in Patients With Intractable Vomiting

OBJECTIVES

Gastric electrical stimulation (GES) is an alternative therapy to treat patients with intractable vomiting. A preclinical study has demonstrated the modulation of the gastrointestinal (GI) peptide ghrelin by GES but such mechanism has never been investigated in patients. The aim of this work was to assess the effect of GES on GI peptide levels in patients with intractable vomiting.

MATERIALS AND METHODS

Twenty-one patients were randomized to receive either ON or OFF GES, 14 completed the study (10 ON, 4 OFF stimulation). Vomiting episodes, gastric emptying, and gastrointestinal quality of life index (GIQLI) were assessed. Gastric and blood samples were collected before and four months after the ON period of gastric stimulation. mRNA and/or peptide levels were assessed in gastric biopsies for ghrelin, leptin, and NUCB2/nesfatin-1 and in duodenal biopsies for glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) using RT-qPCR and multiplex technology. Ghrelin, leptin, GLP-1, PYY, gastric inhibitory peptide (GIP), and NUCB2/nesfatin-1 levels also were quantified in blood samples.

RESULTS

Among clinical parameters, vomiting episodes were slightly reduced by GES (p = 0.09). In tissue, mRNA or protein levels were not modified following chronic GES. In blood, a significant reduction of postprandial PYY levels (p < 0.05) was observed at M4 and a reduction of NUCB2/nesfatin-1 levels in fasted patients (p < 0.05). Increased plasma leptin levels after GES were correlated with reduction of vomiting and improvement of GIQLI.

CONCLUSIONS

GES reduces NUCB2/nesfatin-1 levels under fasting conditions and postprandial PYY levels in patients suffering from nausea and/or vomiting refractory to pharmacological therapies.

Tailored approach to gastroparesis significantly improves symptoms

BACKGROUND

Gastroparesis is difficult to treat and many patients do not report relief of symptoms with medical therapy alone. Several operative approaches have been described. This study shows the results of our selective surgical approach for patients with gastroparesis.

MATERIALS AND METHODS

This is a retrospective study of prospective data from our electronic medical record and data symptom sheet. All patients had a pre-operative gastric emptying study showing gastroparesis, an esophagogastroduodenoscopy, and either a CT or an upper GI series with small bowel follow-through. All patients had pre- and post-operative symptom sheets where seven symptoms were scored for severity and frequency on a scale of 0-4. The scores were analyzed by a professional statistician using paired sample t test.

RESULTS

58 patients met inclusion criteria. 33 had gastric stimulator (GES), 7 pyloroplasty (PP), 16 with both gastric stimulator and pyloroplasty (GSP), and 2 sleeve gastrectomy. For patients in the GSP group, the second procedure was performed if there was inadequate improvement with the first procedure. There was no mortality. The follow-up period was 6-316 weeks (mean 66.107, SD 69.42). GES significantly improved frequency and severity for all symptoms except frequency of bloating and postprandial fullness. PP significantly improved nausea and vomiting severity, frequency of nausea, and early satiety. Symptom improvement for GSP was measured from after the first to after the second procedure. GSP significantly improved all but vomiting severity and frequency of early satiety, postprandial fullness, and epigastric pain.

CONCLUSION

All procedures significantly improved symptoms, although numbers are small in the PP group. GES demonstrates more improvement than PP, and if PP or GES does not adequately improve symptoms GSP is appropriate. In our practice, gastrectomy was reserved as a last resort.

Gastric Electrical Stimulation with the Enterra System: A Systematic Review

Background. Gastric electrical stimulation (GES) is a surgically implanted treatment option for refractory gastroparesis. Aim. To systematically appraise the current evidence for the use of gastric electrical stimulation and suggest a method of standardisation of assessment and follow-up in these patients. Methods. A systematic review of PubMed, Web of Science, DISCOVER, and Cochrane Library was conducted using the keywords including gastric electrical stimulation, gastroparesis, nausea, and vomiting and neuromodulation, stomach, central nervous system, gastric pacing, electrical stimulation, and gastrointestinal. Results. 1139 potentially relevant articles were identified, of which 21 met the inclusion criteria and were included. The quality of studies was variable. There was a variation in outcome measures and follow-up methodology. Included studies suggested significant reductions in symptom severity reporting over the study period, but improvements in gastric emptying time were variable and rarely correlated with symptom improvement. Conclusion. The evidence in support of gastric electrical stimulation is limited and heterogeneous in quality. While current evidence has shown a degree of efficacy in these patients, high-quality, large clinical trials are needed to establish the efficacy of this therapy and to identify the patients for whom this therapy is inappropriate. A consensus view on essential preoperative assessment and postoperative measurement is needed.

Treatment of refractory diabetic gastroparesis: Western medicine and traditional Chinese medicine therapies

Refractory diabetic gastroparesis (DGP), a disorder that occurs in both type 1 and type 2 diabetics, is associated with severe symptoms, such as nausea and vomiting, and results in an economic burden on the health care system. In this article, the basic characteristics of refractory DGP are reviewed, followed by a discussion of therapeutic modalities, which encompasses the definitions and clinical manifestations, pathogenesis, diagnosis, and therapeutic efficacy evaluation of refractory DGP. The diagnostic standards assumed in this study are those set forth in the published literature due to the absence of recognized diagnosis criteria that have been assessed by an international organization. The therapeutic modalities for refractory DGP are as follows: drug therapy, nutritional support, gastric electrical stimulation, pyloric botulinum toxin injection, endoscopic or surgical therapy, and traditional Chinese treatment. The therapeutic modalities may be used alone or in combination. The use of traditional Chinese treatments is prevalent in China. The effectiveness of these therapies appears to be supported by preliminary evidence and clinical experience, although the mechanisms that underlie these effects will require further research. The purpose of this article is to explore the potential of combined Western and traditional Chinese medicine treatment methods for improved patient outcomes in refractory DGP.

Diabetic gastroparesis: functional/morphologic background, diagnosis, and treatment options

The regulation of gastrointestinal motility mainly involves the smooth muscle, neural (extrinsic and intrinsic), and hormonal elements, the glial cells, and the interstitial cells of Cajal. An orchestrated function of all these components is required for the appropriate propulsive movement of the food in the gastrointestinal tract. Gastroparesis, a pathological slowing-down of gastric emptying, is a result of the damage to the tissue elements involved in the regulation of motility. Gastroparesis is one of the well-known complications of long-standing diabetes mellitus. Although it is rarely a life-threatening complication, it has a deteriorating effect on the quality of life, leads to unpredictable oscillation of the blood glucose level, and increases the time required for the absorption of food and medicines. This review describes the clinical characteristics of diabetic gastroparesis and summarizes the organic and functional motility abnormalities caused by this complication. Finally, the currently available and potential future therapeutic approaches are summarized.

Improvement of quality of life and symptoms after gastric electrical stimulation in children with functional dyspepsia

BACKGROUND

Our objective is to evaluate the effect of gastric electrical stimulation (GES) on symptoms and quality of life for pediatric patients with functional dyspepsia (FD).

METHODS

Twenty-four patients (16 female, median 15 years) were treated with GES for FD after a median of 24 months of symptoms (3 months-14 years). At baseline, 46% required tube feeds and 25% parenteral nutrition. Sixty percent had gastroparesis. The PedsQL GI Module (PedsQL) was completed for 18/24 both pre-/post-GES after a median of 8 months. Patients also completed the Symptom Monitor Worksheet (SMW) pre-/post-GES after a median of 6 months. Pre-/post-GES global health was also assessed.

KEY RESULTS

Significant improvements were seen in multiple areas of the PedsQL, including stomach pain/upset, food/drink limits, heartburn/reflux, gas/bloating, patient worry, medication tolerance, and constipation (P < 0.05). A decrease was found in combined symptom severity/frequency based on SMW (P < 0.01). Improvements were made in all categories, including vomiting, nausea, early satiety, bloating, fullness, epigastric pain, and burning (P < 0.01). Improvements in PedsQL/SMW scores remained when analysis was limited to normal or delayed gastric emptying (P < 0.05, P < 0.05). Thirteen percent needed tube feeds and 13% parenteral nutrition after GES. Sixty-five percent reported that their health was much improved after GES vs 15% the same or worse. Five patients experienced complications, primarily mild abdominal discomfort.

CONCLUSIONS & INFERENCES

In the largest series to date of pediatric patients who have undergone GES for FD, we found significant improvements in upper gastrointestinal symptoms, quality of life, and perception of global health. Patients were less dependent on tube feeding or parenteral nutrition.

Efficacy of permanent gastric electrical stimulation for the treatment of gastroparesis and functional dyspepsia in children and adolescents

PURPOSE

Permanent gastric electrical stimulation (GES) has been performed in adults as a treatment for gastroparesis and refractory nausea and vomiting in patients who have failed medical therapy. We assessed the feasibility and clinical outcomes of permanent GES in children.

METHODS

Permanent GES was performed in 16 children (10 females/6 males), median age 15 years (range 4-19 years). All patients had chronic nausea and vomiting refractory to medical therapy and met ROME III criteria for functional dyspepsia. Symptoms, route for nutrition, and satisfaction with procedure were recorded before and after permanent GES. Statistical analysis was performed using paired Student's t test.

RESULTS

After permanent GES, there was significant improvement in severity of vomiting (p=0.0001), frequency of vomiting (p=0.0003), frequency of nausea (p<0.0001), and severity of nausea (p<0.0001). At the time of follow-up, 13/16 were on oral feeds exclusively, two patients on oral plus G-tube feedings, and one patient on oral plus G-tube plus intermittent TPN.

CONCLUSIONS

1). Permanent GES improved health in children with functional dyspepsia and gastroparesis who fail medical therapy. 2). No serious adverse effects of permanent GES were noted. 3). Long-term efficacy and safety of GES therapy in children need to be established.

Long term efficacy of gastric electrical stimulation in intractable nausea and vomiting

BACKGROUND

Although the efficacy of gastric electrical stimulation has been reported in short-term studies, there is a lack of data on the long-term improvement of nausea and vomiting by gastric electrical stimulation in patients with delayed or normal gastric emptying.

METHODS

Thirty-one patients were implanted at our centre for medically refractory severe and chronic nausea and/or vomiting. Patients were evaluated at baseline, 6 months then 5 years after implantation (mean follow-up 80±4 months) using a symptomatic and quality of life scores.

KEY RESULTS

Amongst the 31 patients, 4 were lost to follow-up, 6 explanted due to lack of improvement, and 1 patient died. Out of the 20 patients evaluated over 5 years, the quality of life score showed 27% improvement (p<0.01), including nausea (62%; p<0.01), vomiting (111%; p=0.03), satiety (158%; p<0.01), bloating (67%; p<0.01) and epigastric pain (43%; p=0.03). Over 5 years, 15/20 patients reported a 50% improvement with a global satisfaction rated at 64±6%. Therefore, 15/27 patients (56%) were improved by gastric electrical stimulation over 5 years in intention to treat. Improvement of nausea 6 months after implantation was predictive of 5-year success of gastric electrical stimulation (p=0.04). Finally, patients with delayed gastric emptying or with normal gastric emptying rate before surgery were similarly improved over 5 years (60% versus 50% respectively).

CONCLUSION

Gastric electrical stimulation is safe and effective in the long term in patients with medically refractory nausea and vomiting, with an efficacy over 50% beyond 5 years in intention to treat. Gastric emptying measured before implantation did not influence the response rate over 5 years.

Is symptom relief associated with reduction in gastric retention after gastric electrical stimulation treatment in patients with gastroparesis? A sensitivity analysis with logistic regression models

BACKGROUND

Enterra gastric electrical stimulation (GES) is an alternative treatment for gastroparesis (GP) when standard medical therapy fails. The aims of this study were to evaluate the association between total symptom score (TSS) and reduction in gastric retention (GR) after GES by GP etiology and to examine the sensitivity of the association to varying cutpoints used to define GR and TSS improvement.

METHODS

Gastric retention assessed with a standardized (99m) Tc radio-labeled egg meal and TSS measured by a five-point Likert scale in 221 GP patients treated with Enterra GES therapy for at least 1 year were analyzed. Bivariate chi-square test and multivariable logistic regression with all possible cutpoints were used to assess the consistency of association and quantitate the relationship across three GP etiologies.

KEY RESULTS

Symptom relief in diabetic GP was more likely attributable to GR reduction as indicated by the consistently significant odds ratios (P < 0.01) across all cutpoints. The association in idiopathic GP was inconclusive because odds ratios were sensitive to cutpoints with P-values ranging from 0.01 to 0.47. No association was found for patients with post surgical gastroparesis (P > 0.1 for all cutpoints). Patient age, gender, baseline TSS and baseline GR had no significant effect at 5% level on clinical improvement regardless of cutpoints for GR.

CONCLUSIONS & INFERENCES

Association between clinical improvements and GR reduction following GES treatment depends on patient etiology and was able to be demonstrated in diabetic GP. The association for idiopathic GP was inconclusive and no such association was found for post surgical GP across all possible cutpoint combinations.

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.

Evaluating symptom outcomes in gastroparesis clinical trials: validity and responsiveness of the Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD)

BACKGROUND

Patient-reported symptom scales are needed to evaluate treatments for gastroparesis. The Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD) was developed to assess daily symptoms of gastroparesis. This study evaluated the validity and responsiveness of the GCSI-DD in patients with gastroparesis.

METHODS

Symptomatic patients were started with a new treatment for gastroparesis. Patients completed the GCSI-DD each evening during a baseline week and for 8 weeks of treatment. Responders were defined based on patient and clinician global rating of change. Minimal important differences (MID) were estimated based on baseline to 4 week changes in symptoms scores for small improvements.

KEY RESULTS

Of 69 patients participating, 46 had idiopathic, 19 diabetic, and four postfundoplication gastroparesis. Excellent test-retest reliability was seen for GCSI-DD scores, and there were significant correlations between GCSI-DD scores and clinician ratings of symptom severity. Responders to treatment reported improvements in nausea [effect size (ES) = 0.42, P < 0.001], postprandial fullness, ES = 0.83, P < 0.001), bloating (ES = 0.34, P < 0.001), early satiety (ES = 0.53, P < 0.001), but lower responses for upper abdominal pain (ES = 0.29), and vomiting (ES = 0.22; P = 0.119). MIDs were 0.55 for nausea, 0.97 for excessive fullness, 0.63 for bloating, 0.77 for postprandial fullness, and 0.30 for abdominal pain. A composite score of four symptoms (Composite-1; nausea, bloating, excessive fullness, postprandial fullness) had ES of 0.61 and MID of 0.73. Composite-2 score (nausea, early satiety, bloating, abdominal pain) had a lower ES of 0.47.

CONCLUSIONS & INFERENCES

Symptoms of early satiety, nausea, postprandial fullness, and bloating were responsive to treatment for gastroparesis. A composite of these symptoms also demonstrates validity and responsiveness to treatment for gastroparesis, and may represent an acceptable endpoint for evaluating the effectiveness of medical treatments in clinical trials for gastroparesis.

Gastroparesis: concepts, controversies, and challenges

Patients with gastroparesis often present a challenge to the treating physician. Postprandial symptoms with nausea and vomiting may not only lead to nutritional and metabolic consequences, but also cause significant disruptions to social activities that often center around food. While the definition of gastroparesis focuses on impaired gastric emptying, treatment options that affect gastric function are limited and often disappointing. The female predominance, the mostly idiopathic nature of the illness with a common history of abuse, and coexisting anxiety or depression show parallels with other functional disorders of the gastrointestinal tract. These parallels provided the rationale for some initial studies investigating alternative therapies that target the brain rather than the stomach. This emerging shift in medical therapy comes at a time when clinical studies suggest that gastric electrical stimulation may exert its effects by modulating visceral sensory processing rather than altering gastric motility. Physiologic and detailed anatomic investigations also support a more complex picture with different disease mechanisms, ranging from impaired accommodation to apparent visceral hypersensitivity or decreased interstitial cells of Cajal to inflammatory infiltration of myenteric ganglia. Delayed gastric emptying remains the endophenotype defining gastroparesis. However, our treatment options go beyond prokinetics and may allow us to improve the quality of life of affected individuals.

Ghrelin, appetite and gastric electrical stimulation

Ghrelin is a peptide hormone produced mainly by the stomach and has widespread physiological functions including increase in appetite. The stimulation of the ghrelin system represents a potential therapeutic approach in various disorders characterized by deficient ghrelin signaling or by low appetite. This stimulation may be achieved via pharmacological targeting of the ghrelin receptor with synthetic ghrelin or ghrelin mimetics or via increased endogenous ghrelin production. Recently, it was demonstrated that gastric electrical stimulation (GES) with Enterra parameters results in increased ghrelin production in rats. Furthermore, recent data revealed putative role of ghrelin-reactive immunoglobulins in the modulation of the ghrelin signaling which can be also stimulated by GES. Here, we review the links between GES and ghrelin in existing GES experimental and clinical applications for treatment of gastroparesis, functional dyspepsia or obesity and discuss if GES can be proposed as a non-pharmacological approach to improve ghrelin secretion in several pathological conditions characterized by low appetite, such as anorexia nervosa or anorexia-cachexia syndrome.

Optimizing the diagnostic power with gastric emptying scintigraphy at multiple time points

Background

Gastric Emptying Scintigraphy (GES) at intervals over 4 hours after a standardized radio-labeled meal is commonly regarded as the gold standard for diagnosing gastroparesis. The objectives of this study were: 1) to investigate the best time point and the best combination of multiple time points for diagnosing gastroparesis with repeated GES measures, and 2) to contrast and cross-validate Fisher's Linear Discriminant Analysis (LDA), a rank based Distribution Free (DF) approach, and the Classification And Regression Tree (CART) model.

Methods

A total of 320 patients with GES measures at 1, 2, 3, and 4 hour (h) after a standard meal using a standardized method were retrospectively collected. Area under the Receiver Operating Characteristic (ROC) curve and the rate of false classification through jackknife cross-validation were used for model comparison.

Results

Due to strong correlation and an abnormality in data distribution, no substantial improvement in diagnostic power was found with the best linear combination by LDA approach even with data transformation. With DF method, the linear combination of 4-h and 3-h increased the Area Under the Curve (AUC) and decreased the number of false classifications (0.87; 15.0%) over individual time points (0.83, 0.82; 15.6%, 25.3%, for 4-h and 3-h, respectively) at a higher sensitivity level (sensitivity = 0.9). The CART model using 4 hourly GES measurements along with patient's age was the most accurate diagnostic tool (AUC = 0.88, false classification = 13.8%). Patients having a 4-h gastric retention value >10% were 5 times more likely to have gastroparesis (179/207 = 86.5%) than those with ≤10% (18/113 = 15.9%).

Conclusions

With a mixed group of patients either referred with suspected gastroparesis or investigated for other reasons, the CART model is more robust than the LDA and DF approaches, capable of accommodating covariate effects and can be generalized for cross institutional applications, but could be unstable if sample size is limited.

Short pulse gastric electrical stimulation for cisplatin-induced emesis in dogs

BACKGROUND

In a previous study, we investigated the ameliorating effect of gastric electrical stimulation (GES) with a single set of parameters on emesis and behaviors suggestive of nausea induced by cisplatin in dogs. The aim of this study was to investigate the effects of GES with different parameters on cisplatin-induced emesis in dogs.

METHODS

Seven dogs implanted with gastric serosal electrodes were studied in six randomized sessions: one control session with cisplatin (2 mg kg(-1)) and five sessions with cisplatin plus GES of different parameters: GES-A: 14 Hz, 5 mA, 0.3 ms, 0.1 s on and 5 s off; GES-B: increased frequency and on-time; GES-C: increased frequency; GES-D: increased frequency and pulse width; and GES-E: increased frequency and amplitude. Gastric slow waves and emetic responses were recorded in each session.

KEY RESULTS

(i) Cisplatin induced emetic responses and gastric dysrhythmia. The peak time of the emetic response was during the fourth hour after cisplatin. (ii) GES with appropriate parameters reduced cisplatin-induced emesis. The number of vomiting times during the 6 h after cisplatin was 7.0 ± 1.4 in the control, 4.7 ± 1.2 with GES-A (P = 0.179), 4.2 ± 1.2 with GES-B (P = 0.109), 7.0 ± 0.8 with GES-C (P = 0.928), 2.1 ± 0.3 with GES-D (P = 0.005) and 4.7 ± 1.5 with GES-E (P = 0.129). However, none of the GES parameters could improve gastric dysrhythmia.

CONCLUSIONS & INFERENCES

Gastric electrical stimulation with appropriate parameters reduces cisplatin-induced emetic responses and behaviors suggestive of nausea in dogs. Among the tested parameters, GES with increased pulse width seems to produce better relief of cisplatin-induced emesis.

Does grading the severity of gastroparesis based on scintigraphic gastric emptying predict the treatment outcome of patients with gastroparesis?

OBJECTIVES

The objectives of this study were as follows: (1) Whether gastric emptying is different between gastroparesis (GP) patients responding or not responding to standard medical therapy; (2) Identifying if mild, moderate, and severe degrees of gastroparesis based on the scintigraphic gastric emptying test (GET) can predict treatment responses for GP of diabetic (DM) and idiopathic (ID) origin.

METHODS

A total of 165 patients (119 F) diagnosed with GP [126 (76%) DM, 39 (24%) ID etiology] failed medical treatment and required the gastric electrical stimulation (GES) device (GES group). In addition, 112 patients (89 F) [37 (33%) DM, 75 (67%) ID] with GP who symptomatically responded to medical therapies are the comparison group (MED GP). All patients underwent a standardized scintigraphic GET consisting of low-fat (2%) isotope labeled egg beaters meal of 250 kcal. We also analyzed the GET data to find cut-off points for different degrees of GP and identified mild (11-20% retention), moderate (21-35%), and severe gastroparesis (>35%) based on percent retention of isotope at 4 h.

RESULTS

Overall gastric retention at 4 h was significantly greater in the GES group (45±1.9%) than MED GP (30±2%) (p<0.001). The distribution severity of the GET was different in GES-treated patients than MED treated (p<0.001). In the diabetics, 57% of GES patients retained >35% after 4 h (severe) similar to 43% in the DM MED group. However, 50% of the ID GES patients had retention>35% at 4 h significantly more than only 17% of ID MED GP. Significantly more ID patients who responded to medical therapy had mild gastroparesis and significantly more requiring GES had severe GET (p<0.05).

CONCLUSIONS

(1) GET in patients whose GP symptoms were refractory to standard medical therapy and required GES was significantly slower than in GP patients whose symptoms responded to medical therapy. (2) Stratifying GET into mild, moderate, and severe degrees of gastric retention does not predict whether a medical or surgical approach will be better to control the symptoms of diabetic GP but does correlate with treatment for the idiopathic GP subgroup.

Gastric electrical stimulation for gastroparesis: a goal greatly pursued, but not yet attained

The lack of an effective medical treatment for gastroparesis has pushed the research of new techniques of gastric electrical stimulation (GES) for nearly half a century of experimentation with a large variety of electrical stimuli delivered to the gastric wall of animals and patients with gastroparesis. Three principal methods are currently available: gastric low-frequency/high-energy GES with long pulse stimulation, high-frequency/low-energy GES with short pulse stimulation and neural sequential GES. The first method aims to reset a regular slow wave rhythm, but has variable effects on contractions and requires devices with large and heavy batteries unsuitable for implantation. High-frequency/low-energy GES, although inadequate to restore a normal gastric electro-mechanical activity, improves dyspeptic symptoms, such as nausea and vomiting, giving patients a better quality of life together with a more satisfactory nutritional status and is suitable for implantation. Unfortunately, the numerous clinical studies using this type of GES, with the exception of two, were not controlled and there is a need for definitive verification of the effectiveness of this technique to justify the cost and the risks of this procedure. The last method, which is neural sequential GES, consists of a microprocessor-controlled sequential activation of a series of annular electrodes along the distal two thirds of the stomach and is able to induce propagated contractions causing forceful emptying of the gastric content. The latter method is the most promising, but has been used only in animals and needs to be tested in patients with gastroparesis before it is regarded as a solution for this disease.

Gastric electrical stimulation increases ghrelin production and inhibits catecholaminergic brainstem neurons in rats

Gastric electrical stimulation (GES) is a new therapeutic option for functional dyspepsia and gastroparesis. In addition to ameliorating nausea and vomiting, GES results in improved appetite which is not always associated with accelerated gastric emptying. To explore the central and peripheral factors underlying GES-associated improvement of appetite we developed a GES model in anaesthetized Wistar rats. During laparotomy, two electrodes were implanted into the stomach and high-frequency low-energy GES (14 Hz, 5 mA) was applied. The effects of 1 h GES were compared with sham stimulation. After GES, c-Fos expression was increased in the mucosal and submucosal layers of the stimulated area (174%). In the stomach, GES increased ghrelin mRNA (178%) and doubled the number of ghrelin-positive cells, resulting in elevated plasma levels of ghrelin (2.3 ± 0.2 vs. 1.6 ± 0.2 ng/mL). In the arcuate nucleus of the hypothalamus, GES increased c-Fos (277%) and agouti-related protein (AgRP) mRNA expression (135%). GES reduced the number of c-Fos-positive cells throughout the nucleus of the solitary tract (between 93 and 75% from rostral to caudal levels) including catecholaminergic neurons (81% at caudal level). Gastric emptying, plasma glucose and heart rate variability were not affected by GES. This study shows that GES may improve appetite via stimulation of main orexigenic pathways, including ghrelin production in the stomach and AgRP in the hypothalamus, as well as by reducing the activity of catecholaminergic brainstem neurons.

Preoperative predictors of significant symptomatic response after 1 year of gastric electrical stimulation for gastroparesis

BACKGROUND

In cases of gastroparesis where significant symptoms fail to respond to standard medical therapy, gastric electrical stimulation (GES) may be of benefit. Unfortunately, not all patients improve with this therapy. Reliable preoperative predictors of symptomatic response to GES may allow clinicians to offer this expensive and invasive treatment to only those patients most likely to benefit.

METHODS

Therapy was initiated in 15 patients more than 12 months prior to this retrospective review of our prospectively maintained data. All patients completed a Total Symptom Score (TSS) survey at every encounter as well as the SF-36 quality-of-life instrument prior to surgery. A failure of GES therapy was considered to have occurred when after 1 year of treatment, preoperative TSS had not decreased by at least 20%.

RESULTS

Four patients (4 idiopathic) failed to improve more than 20% on multiple assessments after a year of therapy. All diabetic patients experienced a durable symptomatic improvement with GES. Review of individual items of the TSS revealed that nonresponders experienced less severe vomiting preoperatively.

CONCLUSIONS

Diabetic gastroparesis patients respond best to GES. Responders tend to have more severe vomiting preoperatively. Patients with idiopathic gastroparesis who do not experience severe vomiting should be cautioned about a potentially higher rate of poor response to GES and may be better served with alternative treatments.

A slow caloric satiety drinking test in patients with temporary and permanent gastric electrical stimulation

OBJECTIVES

Improvement of gastric accommodation has been proposed as a potential explanation for the positive effect of gastric electrical stimulation (GES) on nausea/vomiting. A drinking test has been suggested as a noninvasive measure of gastric accommodation capacity.

METHODS

Eight patients with therapy refractory nausea and vomiting and nonapproved diagnosis for GES (chronic intestinal pseudo-obstruction (CIP, n=1), functional dyspepsia (FD, n=3), postsurgical gastroparesis (PSGP, n=4) underwent temporary percutaneous GES for 10-14 days, randomized to stimulation ON or OFF, respectively. 19 patients [CIP (n=1), diabetic gastroparesis (n=5), FD (n=5), idiopathic gastroparesis (n=4), PSGP (n=4)] received permanent GES (Enterra, Medtronic) (follow-up at baseline, 6 and 12 months). At the end of each stimulation period a slow caloric satiety drinking test was performed (Nutridrink 1.5 kcal/ml, 15 ml/min).

RESULTS

Healthy volunteers had higher drinking capacity compared to patients at baseline (1630 + or - 496 kcal vs. 887 + or - 412; P<0.001) and less composite symptom score (128 + or - 51 vs. 235 + or - 83; P<0.001). With temporary percutaneous GES, there was no significant change in drinking capacity during stimulation ON versus OFF (746 + or - 383 vs. 734 + or - 427 kcal) and symptom severity at the drinking test was unchanged. For patients having permanent GES there was no significant difference at 6 months (876 + or - 277 kcal) versus baseline, and no difference between symptomatic responders and nonresponders in change in drinking capacity (P=0.7).

CONCLUSION

GES had no effect on proximal gastric function as evaluated by the slow caloric satiety drinking test. This seems to be the case for patients with approved as well as nonapproved indications for GES, and irrespective of the symptomatic response.

Efficacy of gastric electrical stimulation in improving functional vomiting in patients with normal gastric emptying

The objective of this study is to evaluate the utility of gastric electrical stimulation (GES) in the subgroup of patients with refractory nausea and vomiting in the presence of normal gastric emptying. Eighteen patients (15 females) underwent GES implantation for dyspeptic symptoms in the presence of normal gastric emptying. Upper gastrointestinal (UGI) symptom score, health-related quality of life (HR-QOL), nutritional status and weight, and medication use (prokinetics and antiemetics) were assessed at baseline and at 1 year after GES placement. Twelve patients (two males) were included in the final analysis. All patients had normal gastric emptying scintigraphy at baseline. After 1 year of GES, there was a significant reduction in the UGI symptom score from 18 to 10 (P = 0.001). The physical component score (PCS) of the HR-QOL was also significantly increased from 25 to 42 (P = 0.04). Gastric emptying actually became slower in 29% of those who repeated the test after 1 year. No adverse events related to GES placement were recorded. Results of our study suggest that GES improves dyspeptic symptoms in patients with medically refractory nausea and vomiting independent of its effect on gastric emptying and could be considered as a potential therapy in this clinical setting.

Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting

BACKGROUND

Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders.

PURPOSE

This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

Different faces of gastroparesis

AIM: To test the hypothesis that pain and affect rather than impaired emptying determine symptom severity in patients with gastroparesis.

METHODS: Adult patients with documented gastroparesis were enrolled prospectively in a single center and asked to complete the Gastroparesis Cardinal Symptom Index (GCSI), Hospital Anxiety and Depression Scale (HADS), the Short Form 12 (SF-12) as quality of life index, rate pain severity and answer 10 open-ended questions.

RESULTS: A total of 55 patients (44 women) participated. Idiopathic (n = 29) or diabetic (n = 11) gastroparesis and connective tissue disease (n = 8) were the most common underlying causes. Antiemetics (n = 30) and prokinetics (n = 32) were most often prescribed. Seventeen patients used opioids on a daily basis. Nausea and/or vomiting (n = 28), pain (n = 24) and bloating (n = 14) were most commonly listed as dominant symptoms. Patients subjectively attributed symptom improvement to nutritional and dietary therapy (n = 11), prokinetics (n = 11), antiemetics (n = 10) or analgesic agents (n = 3). In univariate analyses, the physical subscore of the SF-12 and HADS, but not gastric emptying delay or symptom duration significantly correlated with disease severity as measured by the GCSI. In multivariate analyses, the combination of vomiting, bloating and depression best predicted the overall impact on quality of life.

CONCLUSION: The study confirms the importance of pain and affect in gastroparesis, which requires novel approaches to improve more effectively the quality of life in patients with this disorder.

Gastric motor and sensory function

PURPOSE OF REVIEW

Abnormalities of gastric sensory and motor function are considered key players in the pathogenesis of upper gastrointestinal symptoms in functional dyspepsia and in gastroparesis. This review summarizes recent progress in our understanding of gastric sensory and motor function in health and in disease.

RECENT FINDINGS

Although assessment of gastric emptying rate is often used in the clinical work-up of patients with functional dyspepsia or gastroparesis, the correlation with symptoms is generally poor. Central processing, related to psychosocial dysfunction, is increasingly implicated in the pathogensis of gastric hypersensitivity. Meal challenge test and in fact even simple ingestion of a meal induce increased symptom occurrence in functional dyspepsia. Impaired motor function in critically ill patients is increasingly being studied and recognized as a prognostically relevant factor. Studies have reported on pharmacological approaches as well as electrical stimulation in the treatment of gastric sensorimotor dysfunction.

SUMMARY

Progress in our understanding of the normal and abnormal gastric sensory and motor function may lead to new or improved treatment modalities. Areas of recent advances are the role of the central nervous system in visceral hypersensitivity, motor abnormalities of the stomach in critically ill patients and the exploration of novel pharmacotherapeutic approaches.

Loss of intramuscular and submuscular interstitial cells of Cajal and associated enteric nerves is related to decreased gastric emptying in streptozotocin-induced diabetes

Interstitial cells of Cajal (ICC) are associated with afferent innervation and peristalsis of the stomach suggestive of a key role in the pathophysiology of gastroparesis. We studied changes in the density and ultrastructure of ICC and enteric nerves in the streptozotocin-induced diabetes mellitus (STZ-DM) in Wistar rats using immunohistochemistry and electron microscopy. Gastric emptying was studied in vivo by single-photon emission computed tomography. In the STZ-DM antrum, a marked reduction was observed in the density of the intramuscular ICC (ICC-IM) and ICC located at the submucosal border of the circular muscle layer of the antrum (ICC-SM). The surviving ICC showed lamellar bodies and partial vacuolation of the cytoplasm content, loss of connections between ICC-IM and nerves; it appeared that injured ICC-IM developed into fibroblast-like ICC. ICC associated with Auerbach's plexus (ICC-AP) in the antrum and ICC in the fundus were not affected significantly except for a loss of connections with nerve structures. Marked reduction in nerve tissue (Protein Gene Product-9.5 positivity) was also restricted to the muscle layers including nitrergic nerves (neuronal nitric oxide synthase positivity). In vivo assessed gastric emptying was markedly reduced in STZ-DM rats. Our data demonstrate in the STZ-DM rat stomach a decreased density of ICC limited to the antrum and to ICC-IM and ICC-SM, and structural degeneration in ICC-IM and associated nerves with a special emphasis on loss of synaptic connections, accompanied by a decrease in gastric emptying. Hence, in this model of gastroparetic diabetes, regional injury to subsets of ICC and nerves are associated with gastric motor dysfunction.

Review article: gastric electrical stimulation for gastroparesis--physiological foundations, technical aspects and clinical implications

BACKGROUND

Application of electrical stimulation to the gut, primarily the stomach, has rapidly advanced in the last two decades, from mostly animal studies to the clinical arena. Most studies focused on the use of electrical stimulation for gastroparesis, the only approved indication for such intervention.

AIM

To review the physiological basis of gastric electrical activity and the technical aspects and clinical outcome of gastric electrical stimulation (GES) for gastroparesis.

METHODS

PubMed search from 1966 to 2009, using gastroparesis and GES as search terms. Areas in focus were systematically reviewed.

RESULTS

The literature consists of open-label studies, mostly from single centres, published in the last decade. Improvement in symptoms, quality of life and nutritional status was reported by most studies. Physiologically, stimulation parameters approved in clinical practice do not regulate gastric slow wave activity and have inconsistent effect on gastric emptying. The mechanism of action of GES is not fully known, but data support modulation of gastric biomechanical activity and afferent neural mechanisms.

CONCLUSIONS

Gastric electrical stimulation is a helpful intervention in recalcitrant gastroparesis. Controlled studies and better understanding of mechanisms of action of electrical stimulation are needed to evaluate further the clinical utility of this intervention and to exploit its therapeutic potential better.

Development and content validity of a gastroparesis cardinal symptom index daily diary

BACKGROUND

The Gastroparesis Cardinal Symptom Index (GCSI) is a patient-reported outcome for gastroparesis using a two-week recall period. To minimize potential patient recall effects, a daily diary version of the GCSI (GCSI-DD) was developed.

AIMS

To evaluate the content validity of GCSI-DD for the symptoms in patients with documented gastroparesis, to capture symptom variability over time and to compare responses of this GCSI-DD to the original GCSI.

METHODS

In gastroparesis adults with delayed gastric emptying, cognitive debriefing interviews were conducted to elicit their perspective on relevant symptoms of gastroparesis and relevant recall periods and to evaluate patient understanding of GCSI-DD. Patients completed the GCSI-DD daily over a 2-week period and completed the GCSI at baseline and the 2-week follow-up visit.

RESULTS

Twelve gastroparesis patients, of whom five were diabetic and nine women, reported nausea (100%), vomiting (100%), stomach fullness (75%), bloating (58%) and loss of appetite (50%) were important symptoms. All patients understood diary instructions and item content and reported that the diary captured their gastroparesis symptom experience; 83% considered response scales adequate. There was significant daily variability in GCSI-DD scores. Mean GCSI-DD subscale and total scores over 2 weeks correlated strongly (all r > 0.90) with GCSI scores at 2-week follow-up.

CONCLUSIONS

The GCSI-DD includes symptoms relevant to patients with gastroparesis, captures daily variability of those symptoms and has psychometric properties consistent with a good patient-reported outcome endpoint for gastroparesis clinical trials.

Diabetic gastroparesis: diagnosis and management

Gastric emptying is frequently abnormal in patients with long-standing type 1 and type 2 diabetes mellitus. Symptoms commonly associated with disordered gastric emptying include nausea, vomiting, bloating and epigastric pain, while patients are also at risk of malnutrition, weight loss, impaired drug absorption, disordered glycaemic control and poor quality of life. Although often attributed to the presence of irreversible autonomic neuropathy, acute hyperglycaemia represents a potentially reversible cause of gastric dysfunction in diabetes. Scintigraphy represents the gold standard for measuring gastric emptying. The management of diabetic gastroparesis is less than optimal, partly because the pathogenesis has not been clearly defined. Treatment approaches include dietary modification and optimization of glycaemia, and the use of prokinetic drugs, while novel therapies such as gastric electrical stimulation are the subject of ongoing investigation.

Pathophysiology and management of gastroparesis

Gastroparesis is characterized by upper gastrointestinal symptoms associated with delayed gastric emptying, without mechanical obstruction. However, symptoms do not correlate well with the magnitude of delay in gastric emptying. Diabetes mellitus and surgery are the most common causes, although more than 30% of cases are idiopathic. Coordination of insulin action with nutrient delivery is important in diabetics, as postprandial blood glucose levels and gastric emptying are interdependent, and gastroparesis probably represents a major cause of poor glycemic control. Scintigraphy is the gold standard for measuring gastric emptying. Current treatment mainly involves the use of prokinetic drugs. Pyloric botulinum toxin injection and gastric electrical stimulation require more evidence from controlled studies before their use can be recommended. Surgical options remain inadequately studied.

Methods of gastric electrical stimulation and pacing: a review of their benefits and mechanisms of action in gastroparesis and obesity

Development of gastric electrical stimulation techniques for treatment of gastric dysmotility syndromes and obesity has been a long-standing goal of investigators and clinicians. Depending on stimulus parameters and sites of stimulation, such methods have a range of theoretical benefits including entrainment of intrinsic gastric electrical activity, eliciting propagating contractions and reducing symptomatology in patients with gastroparesis and reducing appetite and food intake in individuals with morbid obesity. Additionally, gastric stimulation parameters have extragastrointestinal effects including alteration of systemic hormonal and autonomic neural activity and modulation of afferent nerve pathways projecting to the central nervous system that may represent important mechanisms of action. Numerous case series and smaller numbers of controlled trials suggest clinical benefits in these two conditions, however better controlled trials are mandated to confirm their efficacy. Current research is focusing on novel stimulation methods to better control symptoms in gastroparesis and promote weight reduction in morbid obesity.

Treatment of refractory gastroparesis: gastric and jejunal tubes, botox, gastric electrical stimulation, and surgery

Refractory gastroparesis is a challenging disorder for gastroenterologists, internists, surgeons, and all health care professionals involved in the care of these patients. It should be managed by a stepwise algorithm beginning with dietary modifications, then prokinetic and antiemetic medications, measures to control pain and address psychological issues, and endoscopic or surgical options in selected patients, including placement of feeding jejunostomy tubes.

Gastric electrical stimulation is an effective and safe treatment for medically refractory gastroparesis

BACKGROUND

Gastroparesis is characterized by delayed gastric emptying in the absence of obstruction. Common symptoms include nausea, vomiting, and abdominal pain. Severe gastroparesis can result in recurrent hospitalizations, malnutrition, and even death. Gastric electrical stimulation (GES) is a low morbidity treatment that may be effective in patients who are refractory to medical therapy.

METHODS

For a period of more than 35 months, 19 GES systems were implanted laparoscopically for refractory gastroparesis of diabetic (DG, n = 10), idiopathic (IG, n = 6), or postsurgical (PSG, n = 3) etiology. Total gastroparesis symptom scores (TSS) and weekly vomiting frequency were assessed. Gastric emptying studies were attained preoperatively and after 6 months.

RESULTS

Mean follow-up was 38 weeks. There were no major complications. Within 6 weeks, frequency of vomiting decreased in 75% of DG (6/8) and 100% of IG (4/4) patients. No PSG patient complained of vomiting preoperatively. Mean TSS scores improved significantly at all intervals out to 1 year. Gastric emptying studies normalized in 80% of DG patients but in only 1 of the 6 patients with gastroparesis due to other causes.

CONCLUSION

GES therapy can lead to improvement in symptoms of gastroparesis and frequency of vomiting within 6 weeks. This therapy is a low morbidity treatment option that may help patients whose symptoms fail to improve with medical therapy.

Gastric electric stimulation for the treatment of gastroparesis

Gastric electric stimulation is an emerging therapy for refractory gastroparesis. Several methods have been used to electrically stimulate the stomach. Initial studies used gastric electrical pacing, which entrains and paces the gastric slow waves at a slightly higher rate than the patient's normal myoelectric frequency of 3 cycles per minute (cpm). The technique currently practiced uses high-frequency, low-energy stimulation at four times the basal rate (12 cpm). Results from published studies with high-frequency stimulation reveal an improvement in symptoms, primarily of nausea and vomiting, and primarily in patients with diabetic gastroparesis, with only a modest change in gastric emptying. As treatment with gastric electric stimulation evolves, further delineation of its overall effectiveness, the type of patient that will likely respond, optimal electrode placement(s), and stimulus parameters should be explored.