Botulinum toxin for spastic GI disorders: a systematic review

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.

The role of endoscopy in bariatrics: past, present, and future

The exponential increase in the rate of obesity and its associated co-morbidities has increased the demand for bariatric surgery. Over the past few decades, surgical weight reduction by gastric restriction, malabsorption, or a combination of both has been the preferred approach to achieve sustained weight loss in the morbidly obese. Although extremely effective, surgical procedures carry significant complications and risk with mortality rates of 1%. Because of the cost, surgical risk, and complications, there is a demand for less invasive procedures. Endoscopic approaches include placement of endoluminal space-occupying devices, stapling devices to reduce gastric volume, barrier devices to reduce small bowel absorptive area, and methods to regulate gastric emptying. Current and ongoing studies have delivered promising results across many aspects of endoscopic approaches. However, many technical obstacles still exist that have to be resolved with further research before endoscopic bariatrics can be widely deployed. At present the role of endoscopy is well established in preoperative evaluation as well as in recognition and management of many postoperative complications in bariatrics. In this article, we review the current and future endoscopic methods for weight reduction that are either in practice or in testing.

Botulinum toxin may predict the outcome of endoscopic sphincterotomy in episodic functional post-cholecystectomy biliary pain

OBJECTIVE

A retrospective clinical audit was carried out to identify whether relaxation of the sphincter of Oddi (SO) by botulinum toxin (BTX) injection can select patients with episodic functional post-cholecystectomy biliary pain who will benefit from endoscopic sphincterotomy.

PATIENTS AND METHODS

Sixty-four patients complaining of functional post-cholecystectomy biliary pain with a frequency of at least four episodes per month had 100 units of BTX injected into their SO muscle in four aliquots. After review patients with a pain free interval following BTX injection of at least 4 weeks were offered biliary endoscopic sphincterotomy and their outcome assessed.

RESULTS

Of the 64 patients 46 (72%) had at least four pain free weeks after BTX therapy and 44 of these 46 patients (96%) went on to experience pain relief following endoscopic sphincterotomy. Of the 64 patients 41 had sphincter of Oddi manometry prior to BTX injection. Every patient with sphincter of Oddi hypertension defined by manometry and at least 4 weeks' pain relief following BTX (24) had pain relief following sphincterotomy. Fifteen (94%) of the 16 patients who did not undergo manometry but reported at least 4 weeks' pain relief after BTX had pain relief after sphincterotomy.

CONCLUSION

Botulinum toxin relaxation of the SO may be a useful method of predicting the symptom response to endoscopic sphincterotomy in patients who have episodic functional biliary pain.

Effects of intramural administration of Botulinum Toxin A on gastric emptying and eating capacity in obese patients

BACKGROUND

Intraparietal gastric administration of Botulinum Toxin A has been studied in open trials to induce satiety and increase weight loss of obese patients with contradictory results. In previous studies only the antrum was the target for Botulinum Toxin A, whereas the fundus, which exerts important activity on gastric accommodation, was excluded. In this study we report the effects of injection into both gastric regions on solid gastric capacity and emptying of the stomach.

MATERIALS AND METHODS

In this study we extended our previous investigations to include 30 obese patients who received Botulinum Toxin A (120 U into the antrum and 80 U into the fundus) or saline by intraparietal endoscopic injection. The two groups were homogeneous for age, gender, body weight and body mass index. Body weight and body mass index, solid gastric emptying (T(1/2) and T(lag) at the octanoic acid breath test) and maximal gastric capacity for solids (kcal) were determined before injection and 2 months later. The results were expressed as mean values (S.E.M.). t-Test or Wilcoxon test was used for statistical analysis, p<0.05 being considered significant.

RESULTS

Both treatments induced a significant reduction of body weight and body mass index but Botulinum Toxin A exerted a significantly greater effect (body weight -11.8+/-0.9 kg vs. -5.5+/-1.1 kg, p<0.0002; body mass index -4.1+/-0.2 vs. -2.2+/-0.4, p<0.001). The maximal gastric capacity for solids was also reduced by both Botulinum Toxin A and placebo, the former being significantly more effective (679+/-114 kcal vs. 237+/-94 kcal, p<0.008). Botulinum Toxin A also significantly increased T(1/2) from 83.4+/-3.9 to 101.6+/-9.9 min, p<0.03) but T(lag) was unchanged. Placebo had no effect on either of these parameters.

CONCLUSIONS

Our results demonstrated that Botulinum Toxin A makes weight loss easier in obese patients. It acts by increasing the solid gastric emptying time and reducing the solid eating capacity of the stomach.

Beyond gastric emptying: a "toxic" lesson about gastroparesis

The first published controlled trial of intrapyloric botulinum toxin for gastroparesis failed to demonstrate a significant effect of treatment on symptoms, despite an improvement in gastric emptying. In this editorial, I discuss the limitations and implications of this study, with particular emphasis on what the use of botulinum toxin can teach us about the pathophysiology of gastroparesis and other gastrointestinal smooth muscle disorders.

Treatment of morbid obesity by intraparietogastric administration of botulinum toxin: a randomized, double-blind, controlled study

OBJECTIVE

The stomach is the main target organ for bariatric surgery, but no medical treatment has been developed to increase satiety and decrease food intake via gastric pathways. The aim of our study was to investigate whether or not the intraparietogastric administration of botulinum toxin A (BTX), able to modify the motility patterns of the stomach, could be useful for treatment of obesity.

DESIGN

Double blind controlled study.

SUBJECTS

Twenty-four morbidly obese patients (mean weight (s.e.m.) 116.1+/-4.89 kg, mean body mass index (BMI) 43.6+/-1.09 kg/m(2)) were blindly randomized to receive 200 IU BTX or placebo into the antrum and fundus of the stomach by intraparietal endoscopic administration.

MEASUREMENTS

We evaluated weight loss, BMI changes, satiety score, the maximal gastric capacity for liquids and the gastric emptying time (octanoic acid breath test).

RESULTS

The two groups were homogeneous for anthropometric characteristics. Eight weeks after treatment, BTX patients had significantly higher weight loss (11+/-1.09 vs 5.7+/-1.1 kg, P<0.001) and BMI reduction (4+/-0.36 vs 2+/-0.58 kg/m(2), P<0.001) and a higher satiety score on a visual analogic scale (7.63+/-0.38 vs 4.72+/-0.44, P<0.001) than controls. Furthermore, BTX patients showed a significantly greater reduction in maximal gastric capacity for liquids (266.6+/-48 vs 139+/-31, P<0.001) and a greater prolongation in gastric emptying time (+18.93+/-8 vs -2.2+/-6.9 min, P<0.05). No significant side effects or neurophysiologic changes were found.

CONCLUSIONS

Topical intragastric BTX was effective in reducing food intake and body weight in morbidly obese patients.

Metastatic bone cancer as a recurrence of early gastric cancer - characteristics and possible mechanisms

The surgical outcome of most early gastric cancer (EGC) is usually satisfactory. Some cases show bone metastasis even though the depth of cancer invasion is confined to the mucosa. The most frequent site for recurrence of EGC is the liver. Cases of EGC with bone metastasis are reviewed to clarify the clinicopathological characteristics of EGC giving rise to bone metastasis. Possible mechanisms and risk factors underlying this rare condition are proposed. Forty-six cases of bone metastasis from EGC are reviewed from published reports and meeting proceedings in Japan. This investigation suggests that risk factors for bone metastasis from EGC include depressed-type signet-ring cell carcinoma, poorly differentiated carcinoma, and/or the likely involvement of lymph node metastasis, even though the cancer is confined to the gastric mucosa. The risk factors do not include recurrence of EGC in the liver. We speculate that the mechanism of bone metastasis from EGC is via lymphatic channels and systemic circulation. Post-operative follow-up of cases should consider the development of bone metastasis from EGC. We propose the use of elevated alkaline phosphatase levels for the detection of bone metastasis and recommend bone scintigraphy in positive cases.

Long-term results of pneumatic dilation for achalasia: A 15 years’ experience

AIM: Although most patients with achalasia respond to pneumatic dilation, one-third experienced recurrence, and prolonged follow-up studies on parameters associated with various outcomes are scanty. In this retrospective study, we reported a 15-years’ experience with pneumatic dilation treatment in patients with primary achalasia, and determined whether previously described predictors of outcome remain significant after endoscopic dilation.

METHODS: Between September 1989 and September 2004, 39 consecutive patients with primary symptomatic achalasia (diagnosed by clinical presentation, esophagoscopy, barium esophagogram, and manometry) who received balloon dilation were followed up at regular intervals in person or by phone interview. Remission was assessed by a structured interview and a previous symptoms score. The median dysphagia-free duration was calculated by Kaplan-Meier analysis.

RESULTS: Symptoms were dysphagia (n = 39, 100%), regurgitation (n = 23, 58.7%), chest pain (n = 4, 10.2%), and weight loss (n = 26, 66.6%). A total of 74 dilations were performed in 39 patients; 13 patients (28%) underwent a single dilation, 17 patients (48.7%) required a second procedure within a median of 26.7 mo (range 5-97 mo), and 9 patients (23.3%) underwent a third procedure within a median of 47.8 mo (range 37-120 mo). Post-dilation lower esophageal sphincter (LES) pressure, assessed in 35 patients, has decreased from a baseline of 35.8 ± 10.4-10.0 ± 7.1 mmHg after the procedure. The median follow-up period was 9.3 years (range 0.5-15 years). The dysphagia-free duration by Kaplan-Meier analysis was 78%, 61% and 58.3% after 5, 10 and 15 years respectively.

CONCLUSION: Balloon dilation is a safe and effective treatment for primary achalasia. Post-dilation LES pressure estimation may be useful in assessing response.

Long-term follow-up after pneumatic dilation for achalasia cardia: factors associated with treatment failure and recurrence

BACKGROUND

Though most patients with achalasia cardia (AC) respond to pneumatic dilation (PD), one-third experienced recurrence. Long-term follow-up studies on factors associated with various outcomes are scanty.

METHODS

In this retrospective study, 126 patients (36.5 +/- 14.6 yr, 76 male) with AC (diagnosed by esophagoscopy, barium esophagogram, and/or manometry) were followed up in person or through mail. The median dysphagia-free duration was calculated by Kaplan-Meier analysis. Factors associated with nonresponse and recurrence after PD were determined using univariate and multivariate analyses.

RESULTS

Symptoms were dysphagia (126, 100%), chest pain (21, 17%), regurgitation (61, 48%), weight loss (33, 26%), and pulmonary symptoms (23, 18%); 5 of 126 (4%) had megaesophagus (> or =7 cm). The mean lower esophageal sphincter (LES) pressure was 38.7 +/- 16.8 mmHg. One hundred and fifteen of 126 (91%) patients responded to PD (90 (71%) to first session); 25 of these had recurrence of dysphagia after 15 +/- 17 months. Post-PD chest pain requiring hospitalization occurred in 21 of 126 (17%; one had an esophageal perforation). Post-PD LES pressure, which was assessed in 48 of 126 patients, had decreased by >50% from baseline in 14 of 29 responders, 0 of 11 nonresponders (p= 0.004, chi(2) test), and 5 of 8 relapsers. The median dysphagia-free duration by Kaplan-Meier analysis was 60 months (SE 2.7, 95% CI 54.7-65.3). On univariate analysis, male gender, pulmonary symptoms (nocturnal coughing spell, history of respiratory infection), absence of chest pain, and failure to achieve a reduction in LES pressure >50% after PD were associated with poor outcome; whereas age, grade of dysphagia, regurgitation, megaesophagus, and LES pressure before PD were not. Male gender was associated with poor outcome by multivariate-analysis.

CONCLUSIONS

PD is an effective and safe treatment for AC. Post-PD LES pressure measurement may be helpful in assessing response. Male patients have poorer outcomes following PD.

Treatment of epiphrenic and mid-esophageal diverticula

Thoracic esophageal diverticula are uncommon. They account for less than 30% of esophageal diverticula. The majority of patients are asymptomatic or have minimal symptoms. About one third of patients present with severe symptoms. Occasionally, pulmonary symptoms can be the sole manifestation of the disease and can be life threatening. Dysphagia, food regurgitation, chest pain, weight loss, and reflux symptoms are the most commonly encountered gastrointestinal symptoms. Malignancy is a rare complication of esophageal diverticula; therefore, patients should be educated regarding this complication. Appropriate diagnostic tests should be arranged promptly if alarming symptoms develop. Esophageal motor disorders are found in the majority of patients and need to be taken into account when planning therapy. Medical and endoscopic therapies have limited roles in treatment. Surgery is the standard of care for patients with pulmonary or incapacitating symptoms related to an epiphrenic diverticulum, and myotomy is the cornerstone of surgery. To ensure complete relief of the obstruction, the myotomy should extend distally at least 1.5 to 2 cm into the stomach and proximally at least to the neck of diverticulum. Adding a nonobstructing entireflux procedure is recommended to prevent the development of gastroesophageal reflux disease. Occasionally, a specific treatment such as a diverticulectomy or diverticulopexy needs to be directed to the diverticulum. Preliminary treatment results from minimally invasive surgery, especially laparoscopy, have been promising. In the future with increased experience, minimally invasive surgery may become the standard of care.

Inhibitory effects of botulinum toxin on pyloric and antral smooth muscle

Botulinum toxin injection into the pylorus is reported to improve gastric emptying in gastroparesis. Classically, botulinum toxin inhibits ACh release from cholinergic nerves in skeletal muscle. The aim of this study was to determine the effects of botulinum toxin on pyloric smooth muscle. Guinea pig pyloric muscle strips were studied in vitro. Botulinum toxin type A was added; electric field stimulation (EFS) was performed every 30 min for 6 h. ACh (100 microM)-induced contractile responses were determined before and after 6 h. Botulinum toxin caused a concentration-dependent decrease of pyloric contractions to EFS. At a low concentration (2 U/ml), botulinum toxin decreased pyloric contractions to EFS by 43 +/- 9% without affecting ACh-induced contractions. At higher concentrations (10 U/ml), botulinum toxin decreased pyloric contraction to EFS by 75 +/- 7% and decreased ACh-induced contraction by 79 +/- 9%. In conclusion, botulinum toxin inhibits pyloric smooth muscle contractility. At a low concentration, botulinum toxin decreases EFS-induced contractile responses without affecting ACh-induced contractions suggesting inhibition of ACh release from cholinergic nerves. At higher concentrations, botulinum toxin directly inhibits smooth muscle contractility as evidenced by the decreased contractile response to ACh.

[Digestive tract and botulinum toxin]

INTRODUCTION

the aim of this work was to check literature to assess botulinum toxin injection efficacy in gastrointestinal motor disorders with special emphasis on controlled clinical trials.

METHODS

literature was carried out with the Medline data bank.

RESULTS

seventy three articles in French and in English including a recent general review were retained. Comparative clinical trials only concerned achalasia and anal fissure. The other gastrointestinal motor disorders only gave rise to open non-controlled trials assessed on clinical end points.

DISCUSSION

this review of literature helps to determine usefulness and safety of Botulinum toxin injection in the treatment of esophageal achalasia and anal fissure. The main limitation is its brief duration of action. Studies concerning the others spastic motor disorders are based on unknown physiopathology and controlled trials are required to assess its efficacy.

CONCLUSION

botulinum toxin is increasingly used for gastrointestinal motor disorders with worthwhile results. Its efficacy has been yet established for only two disorders : it has a valuable palliative role in achalasia and may be curative for anal fissure.