Inhibitory effects of botulinum toxin on pyloric and antral smooth muscle

Intrapyloric Botulinum Toxin Injection for Refractory Nausea and Vomiting in Pediatric Patients

OBJECTIVES

Chronic nausea and vomiting may be associated with gastroparesis or other conditions. Poor mechanistic understanding of symptoms often precludes targeted therapy. Numerous case series suggest that intrapyloric botulinum toxin injection (IPBI) may be beneficial in treating gastroparesis and dyspepsia in children. We hypothesized that nausea, vomiting, and other symptoms, independent of gastroparesis, may improve with IPBI. We sought to identify gastric emptying (GE) and manometric patterns in IPBI responders versus nonresponders.

METHODS

Electronic records of 25 pediatric patients who received IPBI for refractory nausea, vomiting, or both were retrospectively reviewed. We assessed symptom improvement post-IPBI and compared symptoms, GE, and antroduodenal manometry (ADM) findings between IPBI responders and nonresponders.

RESULTS

At least one major symptom improved in 19 patients (76%) after IPBI. Of 22 patients completing a GE study, 14 had delayed GE with no significant difference between IPBI responders and nonresponders. Of 22 patients who underwent ADM, 18 had normal fasting peristalsis, 5 had postprandial antral hypomotility, 4 had neuropathic findings, and 19 had pylorospasm. IPBI responders, compared to nonresponders, demonstrated higher antral pressures with feeding ( P < 0.0001) and shorter duration of pylorospasm ( P = 0.0036). Antral pressures did not differ significantly with fasting or following motilin agonists.

CONCLUSIONS

Our findings suggest that IPBI may have therapeutic benefit in pediatric patients with chronic nausea and/or vomiting, independent of gastroparesis. ADM findings of intact antral peristalsis and elevated antral pressures, in conjunction with efficacy of IPBI, support pyloric non-relaxation as a potential contributor to nausea and/or vomiting in pediatric patients.

[Endoscopic intragastric injection of botulinum toxin in the treatment of patients with morbid obesity: opportunities and prospects]

The authors consider modern epidemiological and demographic data on morbid obesity. Literature review is devoted to non-surgical treatment of patients with morbid obesity. The authors analyze the results of experimental and clinical studies on endoscopic intragastric injection of botulinum toxin and bariatric efficacy of this approach. The indications for endoscopic intragastric injection of botulinum toxin and advantages of this technique are clearly formulated. The authors identified the most significant criteria for objective assessment of clinical effectiveness of endoscopic intragastral injection of botulinum toxin, as well as scientific and methodological principles necessary for this technique. Clinical efficacy of intragastric injection of botulinum toxin including overweight loss, anorexigenic and gastroparetic effects indicates inconsistent results and certain unresolved problems. Thus, large-scale multiple-center randomized controlled trials and multivariate analysis are required to determine the role of endoscopic intragastric injection of botulinum toxin in complex treatment of patients with morbid obesity.

Intrapyloric Botulinum Toxin A Injection for Gastroparesis and Functional Upper Gastrointestinal Symptoms in Children: Mayo Clinic Experience, Review of the Literature, and Meta-analysis

OBJECTIVE

We aimed to assess the efficacy of intrapyloric botulinum toxin A injection (IPBTI) in children with and without gastroparesis and to perform a meta-analysis and review of the literature.

METHODS

We retrospectively searched our electronic health records to identify children (aged < 18 years) who underwent an esophagogastroduodenoscopy with IPBTI between 2007 and 2018 for persistent upper gastrointestinal tract symptoms. We included children with and without gastroparesis and excluded children with a history of gastrointestinal surgery, gastrointestinal obstruction, or mucosal disease that could explain their symptoms. A meta-analysis including our study findings was performed.

RESULTS

We identified 20 children (mean [standard deviation] age, 9.7 [5.8] years; 14 [70%] girls) with upper gastrointestinal symptoms who underwent IPBTI at our institution during the study period. Of the 20 children, 17 (85%) underwent gastric emptying scintigraphy, only nine (53%) of whom had gastroparesis. Response to IPBTI was reported in ten children (50%). Response to IPBTI did not differ by the presence of gastroparesis in included children (p = 0.64). Repeated IPBTI was performed in four children who had a response to the first injection; all four reported no benefit from the second IPBTI. There were no reported complications of IPBTI in our cohort. The meta-analysis indicated that 68% (95% confidence interval 59-78) of patients had a response to IPBTI, regardless of the presence of gastroparesis; 66% (95% confidence interval 53-78) of patients who had gastroparesis had a response to IPBTI.

CONCLUSIONS

Intrapyloric botulinum toxin A injection is safe in children and can offer transient relief for patients with refractory upper gastrointestinal symptoms with and without gastroparesis.

Effect of Intragastric Botulinum Type A Injection Combined with a Low-Calorie High-Protein Diet in Adults with Overweight or Obesity

(1) Background/aims: Intragastric botulinum toxin A injection (IGBI) combined with diet control is a new and effective weight loss method for grade 2 obese patients. However, the application of IGIB on overweight or obese adults still needs further research to confirm its efficacy. (2) Methods: We retrospectively collected medical data from 1 July 2021 to 1 January 2022 from a total of 71 patients without diabetes who participated in the bariatric clinic with a body mass index (BMI) > 25 kg/m2. Forty-nine participants opted for intragastric botulinum injection (IGBI) using 300 units of botulinum injected into the antrum, body, and fundus, followed with a low-calorie high-protein diet course. Another 22 people participated only in the low-calorie high-protein diet course as a placebo group. This study analyzes the weight loss percentage of the two groups. Adverse events after IGBI are also reported in a safety assessment. (3) Results: In terms of the characteristics of the two groups, the mean BMI was 29.3 kg/m2 in the IGBI group and 28.0 kg/m in the placebo group (p = 0.63 without significant difference). Comparing the percent weight loss from baseline in the two groups after 12 weeks, the IGBI group lost 11.5% of their body weight and the placebo group lost 1.8%. In terms of group analysis, the percentages of participants with a weight reduction of at least 5% for the IGBI and placebo groups were 95% and 4%, respectively. For weight reduction of at least 10%, these values for the IGBI and placebo groups were 63% and 4%, respectively. In terms of adverse events after IGBI for 12 weeks, 12 participants (24.4%) had constipation, which was the main side effect. No serious adverse events were observed during the study period. (4) Conclusion: The combination of a low-calorie high-protein diet and IGBI is an effective and safe procedure in overweight or obese adults for weight reduction, but further larger studies are needed.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

Gastroparesis in the Hospital Setting

Gastroparesis (GP) is commonly seen in hospitalized patients. Refractory vomiting and related dehydration, electrolyte abnormalities, and malnutrition are indications for hospital admission. In addition, tube feeding intolerance is a common sign of gastric dysmotility in critically ill patients. The diagnosis and management of GP in the hospital setting can be quite challenging. Diagnostic tests are often deferred because of patient intolerance of the oral meal for standard scintigraphy or severity of the primary disease. The diagnosis of GP is often established on the basis of clinical scenario and risk factors for gastric motor dysfunction. Medical therapy in GP is directed toward controlling nausea and vomiting by prokinetic and antinausea medications and correcting nutrition risks or treating malnutrition with nutrition therapy. Enteral nutrition is the preferred nutrition intervention for patients with GP. Delayed gastric emptying in critically ill patients has a negative impact on the timely delivery of enteral feeding and meeting the energy and protein goals. Measures to improve gastric tolerance or provide feeding beyond the stomach are often needed, since early enteral nutrition has been an important target of therapy for critically ill patients. This review will address the current understanding of the mechanisms of GP and feeding intolerance in critical illness, diagnostic workup, drug therapies, and interventions to improve the provision of enteral nutrition in hospital settings when gastric dysmotility is present or suspected.

Endoscopic intragastric injection of botulinum toxin A in obese patients on bariatric surgery waiting lists: A randomised double-blind study (IntraTox study)

BACKGROUND & AIMS

Several studies have evaluated the effect of intragastric injection of botulinum toxin A to treat obesity, achieving mixed results. Our objective is to determine the effect of intragastric botulinum toxin A on weight loss, satiety, biomarkers, and quality of life of obese patients prior bariatric surgery.

METHODS

Design: single-centre, randomised, double-blind, placebo-controlled clinical trial in 52 obese patients on bariatric surgery waiting lists. Two-arm parallel: the treatment group was administered intragastric botulinum toxin A by endoscopy, whereas the control group was administered physiological saline solution. Weight loss was evaluated at weeks 2, 4, 8, 16, and 24, as well as changes in body composition, satiety (Visual analogue scale (VAS) and GCSI questionnaire), quality of life (GIQLI questionnaire), and biomarkers of satiety and appetite.

RESULTS

Weight loss at weeks 2, 4, 8, 16, and 24 after the endoscopy, with respect to the basal visit, was 0.6 ± 2 kg, 0.4 ± 2.7 kg, 0.4 ± 3.1 kg, 0.2 ± 4.5 kg, and 0.6 ± 4.3 kg for the control group vs 1.9 ± 2.1 kg, 2 ± 2.6 kg, 2.8 ± 4.1 kg, 3.5 ± 5.3 kg, and 4.5 ± 7 kg for the treatment group, respectively, being differences between groups significant at all times (p = 0.016, 0.031, 0.014, 0.021, and 0.023, respectively). Treatment group patients obtained a significantly higher score for GIQLI questionnaire compared with baseline (104.4 ± 13.9 points vs 97.7 ± 15.6 points; p = 0.024), showing a significant improvement in the section of subjective physical capacity. No significant differences were found regarding perception of satiety, or biomarkers of satiety and appetite.

CONCLUSIONS

Intragastric injection of botulinum toxin A is an effective and safe procedure to achieve a moderate weight loss and improve quality of life. Registered under clinicaltrialsregister.eu Identifier EudraCT number 2015-004391-29 https://www.clinicaltrialsregister.eu/ctr-search/trial/2015-004391-29/ES.

Botulinum Toxin A Improves Symptoms of Gastroparesis

BACKGROUND AND AIMS

Pyloric injections of botulinum toxin A (BoNT/A) have shown benefit in open-label studies for patients with gastroparesis but not in randomized trials. We sought to examine the effectiveness of BoNT/A injections in a prospective open-label trial of patients with gastroparesis to assess specific symptom improvements over the course of 6 months. We also wanted to determine if specific biochemical measures including creatinine kinase, lactate dehydrogenase, aldolase, and C-reactive protein suggesting muscular injection could be used to predict successful response to pyloric injections of BoNT/A.

METHODS

Patients with gastroparesis undergoing pyloric BoNT/A injections for the treatment of symptomatic gastroparesis were enrolled. The patients completed the Gastroparesis Cardinal Symptom Index (GCSI) at the initial encounter and at 1, 3, and 6 months. Blood samples were collected before and 1 h after BoNT/A therapy.

RESULTS

We enrolled 34 patients for serum analysis of which 25 patients were available for symptom follow-up. Sixty-four percent of patients had an improvement in symptoms at 1 month. Patients with improved GCSI total score at 1 month had an improvement in most individual symptoms evaluated. For patients that improved at 1 month, this improvement often extended up to 6 months (p = 0.04). Serum measures studied did not correlate with clinical outcomes.

CONCLUSIONS

BoNT/A therapy to the pylorus provided symptomatic improvement at 1 month in 64% of patients. For those patients initially responding, the improvement can last out to 6 months. The biochemical markers did not serve to predict the outcome of injections.

The Positive Effects of a Calorie-Restricting High-Protein Diet Combined with Intragastric Botulinum Toxin Type A Application Among Morbidly Obese Patients: A Prospective, Observational Analysis of Eighty-Seven Grade 2 Obese Patients

PURPOSE

Many studies evaluating the effect of intragastric botulinum toxin type A injection (IG-BTxA) for the treatment of obesity have been published. However, none of these studies combined this procedure with a calorie-restricting high-protein diet. Herein, we aimed to evaluate the effects of IG-BTxA application combined with a calorie-restricting high-protein diet.

MATERIALS AND METHODS

This prospective cohort study is conducted with eighty-seven grade 2 obese patients treated between January 2019 and August 2019. Group 1: IG-BTxA + refused to consult the dietitian; group 2: IG-BTxA + get calorie-restricting high-protein diet; group 3: only get a calorie-restricting high-protein diet. Loss of weight, treatment adaptation (visual analog scale score), the status and changes of comorbid conditions, and changes in eating behaviors (Self-Regulation of Eating Behaviour Questionnaire score) were assessed.

RESULTS

Loss of weight, treatment adaptation, and positive behavioral change in eating preferences were significantly higher in group 2 (p = 0.01; p = 0.001; p < 0.01, respectively). Additionally, the decrease in medication requirement for diabetes and hypertension was higher in group 2 (p < 0.05).

CONCLUSION

IG-BTxA application before calorie-restricting high-protein diet facilitates adaptation to the new diet style and helps to lose weight faster in grade 2 obese patients. Also, more positive results were achieved in terms of controlling comorbid diseases.

Diabetic Gastroparesis

This review covers the epidemiology, pathophysiology, clinical features, diagnosis, and management of diabetic gastroparesis, and more broadly diabetic gastroenteropathy, which encompasses all the gastrointestinal manifestations of diabetes mellitus. Up to 50% of patients with type 1 and type 2 DM and suboptimal glycemic control have delayed gastric emptying (GE), which can be documented with scintigraphy, 13C breath tests, or a wireless motility capsule; the remainder have normal or rapid GE. Many patients with delayed GE are asymptomatic; others have dyspepsia (i.e., mild to moderate indigestion, with or without a mild delay in GE) or gastroparesis, which is a syndrome characterized by moderate to severe upper gastrointestinal symptoms and delayed GE that suggest, but are not accompanied by, gastric outlet obstruction. Gastroparesis can markedly impair quality of life, and up to 50% of patients have significant anxiety and/or depression. Often the distinction between dyspepsia and gastroparesis is based on clinical judgement rather than established criteria. Hyperglycemia, autonomic neuropathy, and enteric neuromuscular inflammation and injury are implicated in the pathogenesis of delayed GE. Alternatively, there are limited data to suggest that delayed GE may affect glycemic control. The management of diabetic gastroparesis is guided by the severity of symptoms, the magnitude of delayed GE, and the nutritional status. Initial options include dietary modifications, supplemental oral nutrition, and antiemetic and prokinetic medications. Patients with more severe symptoms may require a venting gastrostomy or jejunostomy and/or gastric electrical stimulation. Promising newer therapeutic approaches include ghrelin receptor agonists and selective 5-hydroxytryptamine receptor agonists.

Endoscopic Botulinum Toxin for Gastroparesis: Results of a Retrospective Series

Beneficial effects of pyloric botulinum toxin injection have been described in a subgroup of gastroparesis patients. Our aim is to evaluate whether clinical, manometric and/or scintigraphic parameters are able to predict treatment outcome. Forty patients (67% female, age 49 (36–56) years) with decompensated gastroparesis treated with botulinum toxin were included in this retrospective analysis. Objective parameters were high-resolution antroduodenal manometry, gastric emptying rate (scintigraphy), and weight change. Subjective treatment outcome was assessed with a Global Physician Assessment Scale. Binary logistic regression analysis was performed to identify predictors for treatment outcome. Fourteen patients (35%) were symptom-responders, and 65% of patients were short-term weight-responders. For both subjective and objective treatment outcome, no differences were found in manometric and scintigraphic variables between responders and non-responders. Neither clinical nor manometric or scintigraphic variables could predict subjective and objective treatment outcome. In conclusion, symptom improvement is achieved in a subgroup of gastroparesis patients treated with endoscopic pyloric botulinum toxin. Although the majority of patients were able to maintain their baseline weight at short-term follow-up, a substantial group of patients needed nutritional interventions on long-term follow-up. However, none of the demographic, clinical, scintigraphic, or antroduodenal manometry variables were able to predict either subjective or objective treatment outcome.

Gastric Per Oral Endoscopic Myotomy (G-POEM) for the Treatment of Refractory Gastroparesis: Early Experience

BACKGROUND

Gastric per oral endoscopic myotomy (G-POEM) of the pylorus is a technique that is recently being used to treat gastroparesis. Our aim was to report our experience in performing G-POEM for refractory gastroparesis of different etiologies and determine symptom improvement.

METHODS

Thirteen patients undergoing G-POEM are reported. Pre- and post-procedure gastric emptying study (GES) and PAGI-SYM for symptom severity were obtained. Patients underwent G-POEM by creating a submucosal tunnel starting in the greater curvature of the distal antrum and extending it to the beginning of the duodenal bulb, followed by a full thickness pyloromyotomy.

RESULTS

All 13 gastroparesis patients successfully underwent G-POEM (one diabetic [DGp], four idiopathic [IGp], eight postsurgical [PSGp]). Postsurgical patients included 4 s/p esophagectomy for esophageal cancer, 3 s/p Nissen fundoplication, and 1 s/p esophagectomy for achalasia. There were no procedure-related side effects. Of 11 patients completing follow-up questionnaires, eight were improved subjectively (four patients reported considerably better, four patients somewhat better, one unchanged, and two worse). Individual symptom severity scores tended to improve, particularly vomiting, retching, and loss of appetite. Of six patients that had post-G-POEM GES; GES improved in four, unchanged in one, and worsened in one).

CONCLUSIONS

G-POEM for treatment of refractory gastroparesis appears to be a feasible and safe technique that can be successfully performed in patients with a variety of etiologies including different types of postsurgical gastroparesis. Our initial experience suggests that the majority of patients report some improvement in symptoms, particularly symptoms of vomiting, retching, and loss of appetite. Further experience is needed to determine the efficacy and safety of G-POEM and predict those who best respond to this treatment.

Endoscopic Interventions in the Treatment of Obesity and Diabetes

Obesity is a global health problem which is on the rise and is strongly associated with the development of type 2 diabetes and other comorbidities. Bariatric surgery is now an established treatment for both these conditions, leading to impressive results in weight loss and glycemic control. More recently, we have seen the development of various endoscopic devices as potential alternatives or adjuncts to bariatric surgery. In this state-of-the-art review, we outline the current landscape of endoscopic treatments available for the management of both obesity and diabetes, including the clinical evidence supporting their use, efficacy, safety, and potential mechanisms of action.

The Role of Endoscopic Intra-Gastric Botulinum Toxin-A for Obesity Treatment

Obesity prevalence has been increasing with devastating health and economic consequences. Botulinum toxin type A (BTX-A), a neurotoxin, is used clinically for conditions characterized by prolonged muscular contraction. Its inhibitory effects on gastric smooth muscles, in theory, make it a potential agent for obesity treatment through delayed gastric emptying and increased satiety. This review aims to examine the evidence for the use of endoscopic BTX-A injection for treating obesity. The literature search identified 60 articles with 11 primary studies as relevant for the scope of the review. Several studies have been conducted to examine the effect of BTX-A injections on obesity, including both animal and human studies. Current evidence from identified studies does not demonstrate sustained weight loss through the use of endoscopic BTX-A injection.

The Effect of Intragastric Administration of Botulinum Toxin Type A on Reducing Adiposity in a Rat Model of Obesity Using Micro-CT and Histological Examinations

Background/Aims

Botulinum toxin type A (BTX), a long-acting inhibitor of muscular contraction in both striated and smooth muscles, is responsible for gastric motility. The aim of this study was to investigate the effects of an endoscopic intragastric BTX injection on weight loss, body fat accumulation, and gastric emptying time.

Methods

The BTX group consisted of 15 obese rats in which 20 U of BTX were injected into the gastric antrum. The saline group consisted of 15 obese rats injected with 20 U of saline, and the control group included 10 obese rats that did not receive a surgical intervention. The gastric emptying time, biochemical parameters, and body fat volume were evaluated using micro-computed tomography (micro-CT) and histologic evaluations.

Results

The postoperative body weight of the BTX group was significantly lower than those of the other groups (p<0.001) at 6 weeks after the operation. The gastric emptying time (156±54 minutes) was significantly delayed in the BTX group. The BTX group showed significantly lower lipid levels than the other groups. A reduction in body fat volume was observed in the BTX group using micro-CT and histological evaluations.

Conclusions

BTX application to the gastric antrum represents a potentially effective treatment for obesity and may help improve the lipid profile by increasing the gastric emptying time.

Translocation and dissemination of botulinum neurotoxin from the intestinal tract

Botulinum neurotoxins (BoNTs) are potent toxins which induce flaccid paralysis by inhibiting the release of acetylcholine at the neuromuscular junctions. They associate with non-toxic proteins (ANTPs or NAPs) to form complexes of various sizes which are resistant to acidic pH and protease degradation. BoNT trafficking from the digestive tract to the target neurons is still a matter of debate. BoNTs use different strategies to pass through the intestinal barrier including passage of BoNT complexes containing hemagglutinins (HAs) via M cells, HA-dependent perturbation of E-cadherin intercellular junctions between enterocytes and paracellular passage of BoNT complexes, and transcytosis of BoNT free of NAPs through certain intestinal epithelial cells. Then, BoNTs target neuronal cells, preferentially cholinergic neurons, in the intestinal mucosa and submucosa. The precise mode of BoNT dissemination until the final target neuro-muscular junctions is still elusive.

Botulinum Toxin A for Controlling Obesity

Rapid growth of the overweight population and the number of obese individuals in recent decades suggests that current strategies based on diet, exercise, and pharmacological knowledge are not sufficient to address this epidemic. Obesity is the result of a high caloric intake and energy storage, not counterbalanced by an equally important energy expense. Botulinum toxin type A (BoNT-A) use is rapidly expanding to include treatment of a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, painful, and cosmetic disorders. Many studies evaluating the effect of BoNT-A in gastric antrum e/o fundus for the treatment of obesity have been published. This treatment modality was based on the observation that gastric injection of BoNT-A in laparatomized rats induced a significant reduction of food intake and body weight. These studies have been published yielding debated results. Differences in the selection of patients, the doses of BoNT-A, the method of administration of the toxin, and the instruments of evaluation of some parameters among these studies may be the cause. In this review, it will study the state-of-the-art use of BoNT-A in obesity basic science models and review the clinical evidence on the therapeutic applications of BoNT-A for obesity.

The Inhibitory Effect of Botulinum Toxin Type A on Rat Pyloric Smooth Muscle Contractile Response to Substance P In Vitro

A decrease in pyloric myoelectrical activity and pyloric substance P (SP) content following intrasphincteric injection of botulinum toxin type A (BTX-A) in free move rats have been demonstrated in our previous studies. The aim of the present study was to investigate the inhibitory effect of BTX-A on rat pyloric muscle contractile response to SP in vitro and the distributions of SP and neurokinin 1 receptor (NK1R) immunoreactive (IR) cells and fibers within pylorus. After treatment with atropine, BTX-A (10 U/mL), similar to [D-Arg¹, D-Phe⁵, D-Trp^7,9, Leu¹¹]-SP (APTL-SP, 1 μmol/L) which is an NK1R antagonist, decreased electric field stimulation (EFS)-induced contractile tension and frequency, whereas, subsequent administration of APTL-SP did not act on contractility. Incubation with BTX-A at 4 and 10 U/mL for 4 h respectively decreased SP (1 μmol/L)-induced contractions by 26.64% ± 5.12% and 74.92% ± 3.62%. SP-IR fibers and NK1R-IR cells both located within pylorus including mucosa and circular muscle layer. However, fewer SP-fibers were observed in pylorus treated with BTX-A (10 U/mL). In conclusion, BTX-A inhibits SP release from enteric terminals in pylorus and EFS-induced contractile responses when muscarinic cholinergic receptors are blocked by atropine. In addition, BTX-A concentration- and time-dependently directly inhibits SP-induced pyloric smooth muscle contractility.

Endoscopic botox injections in therapy of refractory gastroparesis

Gastroparesis (GP) is a common disease seen in gastroenterology practice particularly in western countries, and it may be underdiagnosed. The available drug therapies for this condition are quite disappointing. Botulinum toxin type A (BT) has been found to be effective therapy in various spastic disorders of smooth muscle of gastrointestinal tract. However, the benefits of BT injections in GP have been unclear. Several retrospective and open label studies have shown clinical advantages of intrapyloric Botulinum toxin type A injections, while two small randomized trials did not show positive results. Therefore, the available published studies yielded conflicting results leading to fading out of botox therapy for GP. We recognize possible clinical benefit of BT injections without any disadvantages of this treatment. We are calling for revisiting the endoscopy guided botox therapy in refractory GP. In this review we discuss important features of these studies pointing out differences in results among them. Differences in patient selection, doses and method of administration of botox toxin in the prior studies may be the cause of conflicting results. The mechanism of action, indications, efficacy and side-effects of BT are reviewed. Finally, we recognize limited evidence to recommend BT in GP and calling attention for future research in this field since no advances in drug management had been made in the last two decades.

Endoscopic treatment of gastroparesis

Gastroparesis has traditionally been a largely medically managed disease with refractory symptoms typically falling under the umbrella of the surgical domain. Surgical options include, but are not limited to, gastrostomy, jejunostomy, pyloromyotomy, or pyloroplasty, and the Food and Drug Administration approved gastric electrical stimulation implantation. Endoscopic management of gastroparesis most commonly involves intrapyloric botulinum toxin injection; however, there exists a variety of endoscopic approaches on the horizon that have the potential to radically shift standard of care. Endoscopic management of gastroparesis seeks to treat delayed gastric emptying with a less invasive approach compared to the surgical approach. This review will serve to highlight such innovative and potentially transformative, endoscopic interventions available to gastroenterologists in the management of gastroparesis.

Substance P is essential for maintaining gut muscle contractility: a novel role for coneurotransmission revealed by botulinum toxin

Substance P (SP) is commonly coexpressed with ACh in enteric motor neurons, and, according to the classical paradigm, both these neurotransmitters excite smooth muscle via parallel pathways. We hypothesized that, in addition, SP was responsible for maintaining the muscular responsiveness to ACh. We tested this hypothesis by using botulinum toxin (BoNT/A), a known blocker of vesicular release of neurotransmitters including ACh and neuropeptides. BoNT/A was injected into rat pyloric sphincter in different doses; as control we used boiled BoNT/A. At the desired time point, pylorus was dissected out and pyloric contractility was measured ex vivo in an organ bath and by measuring phosphorylation of myosin light chain 20 (MLC20). BoNT/A (10 IU) significantly reduced the response of pyloric muscle to exogenous ACh, an effect that was accompanied by reduced MLC20 phosphorylation in the muscle. Both effects were reversed by exogenous SP. CP-96345, a NK1 receptor antagonist, blocked the ability of exogenous SP to reverse the cholinergic hyporesponsiveness as well as the reduction in MLC20 phosphorylation induced by BoNT/A. In conclusion, we have identified a novel role for SP as a coneurotransmitter that appears to be important for the maintenance of muscular responsiveness to the principal excitatory neurotransmitter, ACh. These results also provide new insight into the effects of botulinum toxin on the enteric nervous system and gastrointestinal smooth muscle.

Gastric antral injections of botulinum toxin delay gastric emptying but do not reduce body weight

BACKGROUND & AIMS

Gastric injections of botulinum toxin A (BTA) have been reported to delay gastric emptying, increase satiation, and reduce body weight, but there are few data from randomized, placebo-controlled studies.

METHODS

We enrolled 60 obese participants in a 24-week, double-blind, randomized, placebo-controlled, concealed allocation trial to compare the effects of gastric antral injections of BTA (100, 300, or 500 U) and saline placebo. The study was conducted at an outpatient clinical research unit. Participants were given one set of injections of BTA or placebo into the gastric antral muscularis propria by using endoscopic ultrasound guidance. Gastric emptying of solids was measured by scintigraphy; we also measured body weight, satiation (maximum tolerated volume in a caloric liquid drink test), calorie intake (by food frequency questionnaire), gastrointestinal symptoms, and psychological aspects of eating behavior (by rating scale).

RESULTS

Compared with baseline values, 2 weeks after injections, the mean half-time for gastric emptying of solids increased by 0.8, 14, 24, and 14 minutes among subjects given placebo, 100, 300, or 500 U BTA, respectively (P = .24 overall, P = .04 for the group given 300 U vs placebo); 16 weeks after the injections, mean body weights were reduced by 2.2, 0.2, 2.3, and 3.0 kg in these groups, respectively. There were no statistically significant differences in mean body weight change, satiation volume, caloric intake, gastrointestinal symptoms, or psychological aspects of eating behavior among groups.

CONCLUSIONS

Gastric antral injections of BTA may delay gastric emptying at a dose of 300 U but do not cause early satiety, altered eating behaviors, or loss of body weight. Clinicaltrials.gov identifier: NCT00976443.

A direct inhibitory effect of botulinum toxin type A on antral circular muscle contractility of guinea pig

PURPOSE

Recent studies suggest new mechanisms of Botulinum toxin (BoNT) other than inhibiting acetylcholine (ACh) release from nerve terminals. The aim of this study was to determine whether other mechanisms for BoNT exist, so that it directly inhibits smooth muscle contraction.

MATERIALS AND METHODS

Guinea pig antral muscle strips were studied in vitro after 2 hours of exposure to Botulinum toxin type A (BoNT/A). Contractile responses to electric field stimulation (EFS), high K(+) (60 mM) and ACh (100 μM) were evaluated 24 and 48 hours after antral intramuscular injection of BoNT/A or vehicle.

RESULTS

BoNT/A inhibited muscular contraction caused by high K(+) and ACh. Contractile responses to low (1 and 4 Hz) and high (8 and 20 Hz) frequency EFS of antral muscle strips 24 and 48 hours after antral intramuscular injection of BoNT/A were significantly inhibited.

CONCLUSION

The ability of BoNT/A to directly inhibit antral muscular contractility suggests a new mechanism for the pharmacologic actions of BoNT-direct inhibition of muscular contraction.

Preferential entry of botulinum neurotoxin A Hc domain through intestinal crypt cells and targeting to cholinergic neurons of the mouse intestine

Botulism, characterized by flaccid paralysis, commonly results from botulinum neurotoxin (BoNT) absorption across the epithelial barrier from the digestive tract and then dissemination through the blood circulation to target autonomic and motor nerve terminals. The trafficking pathway of BoNT/A passage through the intestinal barrier is not yet fully understood. We report that intralumenal administration of purified BoNT/A into mouse ileum segment impaired spontaneous muscle contractions and abolished the smooth muscle contractions evoked by electric field stimulation. Entry of BoNT/A into the mouse upper small intestine was monitored with fluorescent HcA (half C-terminal domain of heavy chain) which interacts with cell surface receptor(s). We show that HcA preferentially recognizes a subset of neuroendocrine intestinal crypt cells, which probably represent the entry site of the toxin through the intestinal barrier, then targets specific neurons in the submucosa and later (90–120 min) in the musculosa. HcA mainly binds to certain cholinergic neurons of both submucosal and myenteric plexuses, but also recognizes, although to a lower extent, other neuronal cells including glutamatergic and serotoninergic neurons in the submucosa. Intestinal cholinergic neuron targeting by HcA could account for the inhibition of intestinal peristaltism and secretion observed in botulism, but the consequences of the targeting to non-cholinergic neurons remains to be determined.

Botulism is a severe and often fatal disease in man and animals characterized by flaccid paralysis. Clostridium botulinum produces a potent neurotoxin (botulinum neurotoxin) responsible for all the symptoms of botulism. Botulism is most often acquired by ingesting preformed botulinum neurotoxin in contaminated food or after intestinal colonization by C. botulinum under certain circumstances, such as in infant botulism, and toxin production in the intestine. The first step of the disease consists in the passage of the botulinum neurotoxin through the intestinal barrier, which is still poorly understood. We investigated the trafficking of the botulinum neurotoxin in a mouse intestinal loop model, using fluorescent HcA (half C-terminal domain of the heavy chain). We observed that HcA preferentially recognizes neuroendocrine intestinal crypt cells, which likely represent the entry site of the toxin through the intestinal barrier, then targets specific neurons, mainly cholinergic neurons, in the submucosa, and later (90–120 min) in the musculosa leading to local paralytic effects such as inhibition of intestinal peristaltism. These results represent an important advance in the understanding of the initial steps of botulism intoxication and can be the basis for the development of new specific countermeasures against botulism.

Endoscopic intrapyloric injection of botulinum toxin A in the treatment of children with gastroparesis: a retrospective, open-label study

BACKGROUND

Botulinum toxin A has been used in children to treat spastic disorders and recently for GI conditions. Open-label studies in adults with gastroparesis have reported an improvement in symptoms and gastric emptying after endoscopic intrapyloric botulinum injections (IPBIs), although placebo-controlled trials have shown conflicting results. Only a single case report of IPBI is available in children.

OBJECTIVE

To determine the long-term clinical outcomes and predictive factors for IPBI response in children with gastroparesis refractory to medical therapy.

DESIGN

Retrospective review.

SETTING

Single tertiary care center.

PATIENTS

Children with refractory gastroparesis symptoms undergoing IPBIs.

INTERVENTIONS

IPBIs.

MAIN OUTCOME MEASUREMENTS

Clinical improvement and predictive factors for response.

RESULTS

A total of 70 injections were given to 47 patients (mean age 9.98 ± 6.5 years; 23 female patients) with follow-up in 45 patients. IPBI failed in 15 patients and was successful in 30 patients. The median duration of response to the first IPBI was 3.0 months (95% CI, 1.2-4.8). A total of 29 patients received a single IPBI, and 18 received multiple IPBIs. Older age and vomiting predicted response to initial IPBI, and male sex predicted response to repeat IPBI. Only 1 patient reported exacerbation of vomiting after IPBI resolving within a week.

LIMITATIONS

The open-label and retrospective nature of the study.

CONCLUSION

IPBI is safe and may be effective in the management of children with symptoms of gastroparesis. Subgroups identifying who responded to the first IPBI include older patients and those presenting with vomiting, whereas male patients responded better to repeat IPBIs.

Regional differences in neostigmine-induced contraction and relaxation of stomach from diabetic guinea pig

Delayed gastric emptying and autonomic neuropathy have been documented in patients with diabetes mellitus. Some medications used to treat delayed gastric emptying enhance release of acetylcholine from autonomic neurons to strengthen gastric contractions. Autonomic coordination among gastric regions may be altered in diabetes resulting in poor outcomes in response to prokinetic drugs. Fundus, antrum, and pylorus from STZ or control guinea pigs were treated with neostigmine to mimic release of acetylcholine from autonomic neurons by prokinetic agents. In diabetic animals, neostigmine-induced contractions were weaker in fundus and pylorus but similar in antrum. The muscarinic receptor antagonist 4-DAMP or the nicotinic receptor antagonist hexamethonium reduced neostigmine-induced contractions. Activation of presynaptic muscarinic receptors on nitrergic neurons was impaired in fundus and antrum from diabetic animals. Nerve-stimulated contractions and relaxations, number of nNOS myenteric neurons, and tissue choline content were reduced in fundus from diabetic animals. Despite reduced number of myenteric neurons, tissue choline content was increased in antrum from diabetic animals. Since cholinergic motility of each gastric region was affected differently by diabetes, prokinetic drugs that nondiscriminately enhance acetylcholine release from autonomic neurons may not effectively normalize delayed gastric emptying in patients with diabetes and more selective medications may be warranted.

Endoscopic ultrasound-guided gastric botulinum toxin injections in obese subjects: a pilot study

BACKGROUND

Gastric injections of botulinum toxin A (BTA) may induce changes in gastric emptying and body weight, but results vary. BTA dose and depth of injection may affect efficacy. This study assessed changes in gastric emptying, satiation, symptoms, and body weight after endoscopic ultrasound (EUS)-guided injection of 100 or 300 U BTA into gastric antral muscularis propria of obese subjects.

METHODS

Open label study of ten healthy, obese adults (age = 29-49 years, body mass index = 31-54 kg/m(2)) who received 100 U (n = 4) or 300 U (n = 6) BTA and were followed for 16 weeks. Measures included gastric emptying of solids (by scintigraphy), satiation (by maximum tolerated volume [MTV] during nutrient drink test), gastrointestinal symptoms (by the Gastrointestinal Symptom Rating Scale), caloric intake (by food frequency questionnaire), and body weight.

RESULTS

For the entire cohort, MTV decreased from 1,380 cc (range: 474-2,014) at baseline to 620 cc (range: 256-1,180) 2 weeks after BTA injection; decreases were statistically significant in the subjects receiving 300 U BTA (p = 0.03). Average body weight loss was 4.9 (+/-6.3) kg after 16 weeks. Gastric emptying T(1/2) was prolonged in the 300 U BTA group, but not significantly different from baseline (p = 0.17). BTA injections were well tolerated without significant adverse effects.

CONCLUSION

EUS-guided injection of BTA into gastric muscularis propria can be performed safely with minimal adverse effects. A dose of 300 U BTA significantly enhances satiation, is associated with weight loss, and may slow gastric emptying. Further study of higher dose BTA in obese subjects is warranted.

Intragastric injection of botulinum toxin A for the treatment of obesity

BACKGROUND

Botulinum toxin A (BTX-A) is a powerful and long-acting inhibitor of muscular contractions in both striated and smooth muscles. Hypothetically, BTX-A should inhibit the acetylcholine-mediated peristalsis, which is mainly responsible for gastric motility, and thereby induce slowed gastric emptying, earlier satiety and weight loss. The aim of this study was to observe the effects of endoscopic intragastric injections of BTX-A in obese patients.

METHODS

After approval by the University Ethics Committee, 10 female patients with class I obesity (body mass index 30-35) were double-blind randomized into 2 groups (BTX-A and 0.9% Saline). In Group 1, 200 U BTX-A were injected endoscopically into the antrum and the distal gastric body. In Group 2, 0.9% saline was injected endoscopically into the antrum and the distal gastric body. Body weight and feeling of satiety were recorded monthly over a period of 6 months.

RESULTS

Both groups (BTX-A and 0.9% Saline) showed no significant weight reduction (P>0.05). One patient in Group 1 and two patients in Group 2 reported a feeling of early satiety. No adverse effects related to BTX-A or complications resulting from the endoscopic procedure were observed.

CONCLUSION

Intragastric injection of BTX-A for the treatment of obesity does not seem to reduce body weight.

Effects of Botulinum Toxin A on the Contractile Function of Dog Prostate

OBJECTIVES

To study effects of botulinum toxin A (BoNT/A) on prostate contractile function in dogs.

METHODS

One hundred units (N=6) or 200 units (N=5) BoNT/A was injected into dog prostate. Sham control group (N=7) received normal saline injections. Before and 1 mo after injection, prostate urethral pressure response to electrostimulation and intravenous (IV) norepinephrine was measured. Contractile responses of prostate strips were tested in tissue bath. Structural changes were evaluated with conventional histology and smoothelin immunohistochemistry.

RESULTS

Injection of normal saline and 100 units BoNT/A did not significantly change prostate urethral pressure response to IV norepinephrine and electrostimulation. However, injection of 200 units BoNT/A significantly reduced prostate urethral pressure response to IV norepinephrine and electrostimulation. Contractile responses of prostate strips to potassium chloride, electrostimulation, and phenylephrine did not differ between sham control and 100U groups. In the 200U group, however, all responses were less than those of sham controls. Control and BoNT/A groups exhibited nitric oxide-related relaxation in prostate strips precontracted by phenylephrine. Injection of 100 units BoNT/A induced mild atrophy of prostate gland; injection of 200 units BoNT/A induced more pronounced atrophic changes in prostate gland and vacuoles formation in smooth muscle cells of stromal tissue.

CONCLUSIONS

Injecting BoNT/A into dog prostate reduces contractile function while maintaining relaxation response of the prostate. These effects make BoNT/A a viable option in managing prostate-related symptoms. However, large, randomized clinical studies to determine long-term effects and safety of BoNT/A application in human prostates are required.

Botulinum toxin type A inhibits rat pyloric myoelectrical activity and substance P release in vivo

The effect of botulinum toxin type A (BTX-A) on rat pyloric myoelectrical activity in vivo and the content and distribution of substance P (SP) in pylorus were investigated, respectively, with electromyography, radioimmunoassay, and immunohistochemistry. A pair of electrodes for recording pyloric myoelectrical activity and a guide cannula for drug injection were implanted into the pylorus. The changes of pyloric myoelectrical activity were recorded followed vehicle, 10, 20, and 40 U/kg body mass of BTX-A injection. Pyloric tissues were dissected for radioimmunoassay and immunohistochemistry after recording. The 3 dosages of BTX-A injections caused the reduction of slow wave of pyloric myoelectrical activity in amplitude but not in frequency and the diminishment of spike activity in amplitude and spike burst. The inhibitory effect of 20 U/kg BTX-A was significantly different from that of 10 U/kg (p<0.05), but not from the effect of 40 U/kg administration (p>0.05). After BTX-A intrasphincteric injection, SP content was reduced in the pylorus, and cell number of SP-immunoreactivity was decreased more in myenteric nerve plexus of circular muscle and in mucosa of pylori. In conclusion, BTX-A inhibits pyloric myoelectrical slow activity in amplitude and spike activity and weakens pyloric smooth muscle contractility depending on threshold of dose or concentration. BTX-A-induced inhibition of pyloric myoelectrical activity implies a mechanism of inhibiting SP release from the autonomic and enteric nervous terminals in the pylorus.

Botulinum toxin for gastrointestinal disorders: therapy and mechanisms

Botulinum toxin has gained widespread acceptance as a treatment option for various spastic gastrointestinal disorders such as achalasia, gastroparesis, sphincter of Oddi dysfunction, chronic anal fissures, and pelvic floor dyssnergia, despite the lack of strong evidence supporting its use in many of these diseases. This review summarizes the trials investigating the use of BoNT since it was first utilized as a treatment in achalasia. BoNT has proven to be safe, but long-term efficacy in many disorders has not been observed, primarily due to is relatively short duration of action. BoNT may be most useful in confirming a diagnosis which can lead to a more definitive treatment modality. Furthermore, its safety profile allows it to be a useful alternative in patients who are at high risk for invasive procedures.

Effect of botulinum toxin antral injection on gastric emptying and weight reduction in obese patients: a pilot study

BACKGROUND

A potential approach to the treatment of morbid obesity is reduction of gastric emptying to achieve satiety. Botulinum toxin A (Btx-A) is a long-acting inhibitor of acetylcholine-mediated peristalsis, which is mainly responsible for gastric motility.

AIM

To investigate whether botulinum toxin A, injected in the antrum of obese patients, delays gastric emptying.

METHODS

In a double_blind study, 18 healthy obese subjects (body mass index >30) were randomized into three groups (BTX133, BTX200 and Saline); they received Btx-A133U, Btx-A200U, or saline under endoscopic control. Gastric emptying was tested by scintigraphy before and 10 days after treatment. Body weight variations and appetite sensation were recorded after 5 weeks.

RESULTS

Fourteen patients completed the study. The botulinum toxin A-treated groups showed weight reduction, which was not statistically significant. The effects on gastric emptying were variable. Most of the botulinum toxin A treated patients reported a reduced appetite.

CONCLUSION

This pilot clinical trial suggests potential activity of botulinum toxin A for the manipulation of appetite.

Intrapyloric injection of botulinum toxin a for the treatment of persistent gastroparesis following successful pancreas transplantation

Intrapyloric injection of botulinum toxin A (BoTx) successfully improved symptoms in idiopathic and diabetic gastroparesis (DGP) refractory to medical treatment. Therefore, we used it in three pancreas transplant patients done in our institution during the last 18 months. They had severe, persistent DGP despite successful pancreas transplantation. They received 100 units of BoTx during the first injection. The clinical effect became evident within 2 weeks after the treatment, and lasted for an average of 29 weeks (range 14-44 weeks). The patients' subjective evaluation showed improvement of their symptoms and quality of life following BoTx. Patients 2 and 3 had recurrent symptoms at 44 and 24 weeks, respectively, after the first injection; they required a second dose of 90 and 80 units, respectively. They are doing well at 3 months follow-up. Intrapyloric injection of BoTx is safe and efficient. It should be considered for treating residual DGP following successful pancreas transplantation.

Endoscopic pyloric injection of botulinum toxin A for the treatment of refractory gastroparesis

BACKGROUND

Botulinum toxin A injected into the pyloric sphincter has been reported in small case series to treat gastroparesis. This study reviews the use of this treatment in a large number of patients with gastroparesis.

METHODS

Patients who underwent pyloric botulinum injection for treatment of gastroparesis were identified. Response was defined as improvement or resolution of the patient's major symptom and/or two minor symptoms for 4 weeks.

RESULTS

Of 115 patients treated, 63 patients met the study criteria. There were 53 women, 10 men, mean age 42 years. Most patients (56%) had idiopathic gastroparesis. Twenty-seven of 63 (43%) patients experienced a symptomatic response to treatment. By stepwise logistic regression, male gender was associated with response to treatment (OR 3.27: 95% CI[1.31, 8.13], p = 0.01). Vomiting as a major symptom was associated with a lack of response (OR 0.16: 95% CI[0.04, 0.67], p = 0.01). Despite the association of male gender with response, the mean duration of response for those patients responding, with a minimum of 3 months' follow-up was 4.9 months (+/-2.7 months) for women and 3.5 months (+/-0.71 months) for men (p = 0.59). The corresponding medians and interquartile ranges (IQR) were 5 (IQR 3-6) for females and 3.5 (IQR 3-4) for males.

CONCLUSIONS

Of the patients, 43% had a response to botulinum toxin treatment that lasted a mean of approximately 5 months. Male gender was associated with a response to this therapy; however, durability of response was unrelated to gender. Vomiting as a major symptom predicted no response.