© 2004 by the American Diabetes Association, Inc.
The Treatment of Diabetic Gastroparesis With Botulinum Toxin Injection of the Pylorus
1 Marvin M. Schuster Center for Digestive and Motility Disorders, Johns Hopkins University, School of Medicine, Baltimore, Maryland Address correspondence and reprint requests to Brian E. Lacy, PhD, MD, Dartmouth-Hitchcock Medical Center, Section of Gastroenterology, 1 Medical Center Dr., Lebanon, NH 03756. E-mail: brian.lacy{at}hitchcock.org
OBJECTIVEGastroparesis is a disorder of delayed gastric emptying that is often chronic in nature. Up to 50% of type 1 diabetic subjects have symptoms of gastroparesis, which include nausea, vomiting, and early satiety. Elevated pyloric pressures may be responsible for delayed gastric emptying in diabetic subjects. Botulinum toxin inhibits the release of acetylcholine and produces transient paralysis when injected into smooth muscle. The aim of this study was to determine whether injection of the pylorus with botulinum toxin in patients with diabetic gastroparesis improves symptoms of gastroparesis, alters gastric emptying scan time, and/or changes weight and insulin use. RESEARCH DESIGN AND METHODSThis was an open-label trial with age- and sex-matched control subjects from a tertiary care referral center for patients with gastroparesis. Eight type 1 diabetic subjects (six women and two men; mean age 41 years; mean years with diabetes 25.3) who had failed standard therapy were enrolled. Intervention consisted of injection of the pylorus with 200 units of botulinum toxin during upper endoscopy. Symptoms, antropyloric manometry, gastric emptying scan times, weight, and insulin use were all recorded before intervention and during a 12-week follow-up period. RESULTSSeven of the eight patients completed the full 12-week follow-up period. No complications were noted. Mean symptom scores declined from 27 to 12.1 (P < 0.01), whereas the SF-36 physical functioning domain also improved (P < 0.05). Four patients noted an increase in insulin use of >5 units/day. Six of the seven patients gained weight (P = 0.05). Gastric emptying scan time improved in four patients. CONCLUSIONSBotulinum toxin injection of the pylorus is safe and improves symptoms in patients with diabetic gastroparesis. These results warrant further investigation with a large, double-blind, placebo-controlled trial.
Abbreviations: LES, lower esophageal sphincter
Gastroparesis is a disorder of gastrointestinal motility defined as a delay in gastric emptying in the absence of mechanical obstruction. Common symptoms include early satiety, nausea, vomiting, anorexia, weight loss, and epigastric pain. Gastroparesis is a common problem in type 1 diabetic subjects (1,2), especially in the presence of hyperglycemia (3). Treatment options include erythromycin (4,5), metoclopramide (6), domperidone (7), and cisapride (8), although all of these medications have limitations. Pylorospasm is thought to be a contributing factor in the development of diabetic gastroparesis (9). Reports of intrapyloric botulinum toxin injection to relieve symptoms of gastroparesis (1014) prompted us to perform a trial in eight patients with severe diabetic gastroparesis who had failed standard therapy. The hypothesis was that elevated pyloric pressures delay gastric emptying, and thus transient paralysis of the pylorus should accelerate gastric emptying and improve symptoms of nausea and vomiting. Preliminary data from this study was presented in abstract form at the American College of Gastroenterology meetings in September 2000 (12).
Pylorospasm was first documented by comparing antropyloric manometry findings between diabetic patients and age- and sex-matched healthy volunteers. Pylorospasm was not present in any of the volunteers. Using a prospective, open-label design, diabetic patients with severe gastroparesis were treated with intrapyloric injections of botulinum toxin. Effectiveness was assessed by comparing symptoms, weight, insulin use, gastric emptying, and antropyloric manometry recordings at baseline and after botulinum toxin injection. Eight patients with type 1 diabetes (six women and two men) were enrolled in this study. The mean age was 41 years (range 3646), with a mean duration of diabetes of 25.3 years (range 1040) and mean insulin use of 24.4 years (range 1040). All patients had been referred to the Marvin M. Schuster Motility Center for further evaluation due to persistent symptoms of gastroparesis despite the use of standard medications. Mechanical obstruction had been ruled out in all patients by the referring physicians using a number of different tests (upper endoscopy [esophagogastroduodenoscopy], small bowel follow-through, and computed tomography scan of the abdomen and pelvis). A solid-phase gastric emptying scan was delayed in all eight patients. The control group consisted of age- and sex-matched control subjects without diabetes and without any complaints referable to the gastrointestinal system. Exclusion criteria for both groups were as follows: pregnancy; known allergy to eggs, botulinum toxin, or lidocaine; previous surgery to the stomach, pylorus, or small bowel; previous Nissen fundoplication or other antireflux surgery; known pyloric stricture; previous stroke, transient ischemic attack, or chronic diseases involving the central nervous system; concurrent use of opiates or anticholinergics. Women of child-bearing age had both urine and serum human chorionic gonadotropin checked to ensure that they were not pregnant before testing and treatment. Prokinetic and antiemetic agents were continued during the trial; however, new medications were not initiated during the trial. All patients stayed on a gastroparesis diet (small frequent meals low in both fat and fiber). This protocol was approved by the Institutional Review Board of Johns Hopkins Bayview Medical Center.
Gastric emptying scans
Antropyloric manometry
After topical anesthesia (2% lidocaine HCl; AstraZeneca, Wilmington, DE) to the nose, the catheter assembly was positioned across the pylorus using fluoroscopic guidance. Accommodation time of
Analysis of antropyloric manometry
Symptom questionnaires and weights
Laboratory studies
Injection of the pylorus
Statistics
Symptoms The mean symptom score of all eight patients before treatment was 27.0. Mean symptom scores at weeks 1, 4, 6, and 8 were 14.5, 11.4, 12.1, and 12.2, respectively, for all eight patients (Fig. 1). One patient (C.F.) developed severe nausea and vomiting at week 9 and underwent repeat endoscopy with a second injection (200 units) of botulinum toxin without any complications. Symptoms of nausea and vomiting completely resolved after the second injection. This patients symptom scores are included for follow-up weeks 18 but not week 12. Symptom scores of the seven patients who completed all 12 weeks of follow-up after only one injection of botulinum toxin were not significantly different from the scores listed above for all eight patients and were all significantly reduced compared with baseline (P < 0.01 at all visits).
SF-36 scores and SCL-90 scores were measured both before and after botulinum toxin injection of the pylorus. Two patients did not completely fill out both sets of forms and thus were excluded from analysis. In the six patients who completely filled out both pre- and postinjection SF-36 questionnaires, total scores did not change significantly. However, subscores for the physical functioning domain did improve (P < 0.05). No significant differences were noted in SCL-90 scores over the 12-week follow-up period.
Gastric emptying scans
Antropyloric manometry
Laboratory tests Values for the complete blood count, blood urea nitrogen, creatinine, fasting glucose, HbA1c, albumin, and urinalysis obtained at the 8-week follow-up visit were not significantly different from baseline.
Insulin use
Medication use
Weight
Complications
Several research studies have shown that achalasia, a disorder of esophageal motility characterized by dysphagia and poor emptying of the esophagus, can be effectively treated with botulinum toxin (1618). Injection of the lower esophageal sphincter (LES) with botulinum toxin relaxes the LES, improves esophageal emptying, and improves complaints of dysphagia with minimal side effects. Investigations in our laboratory led us to believe that diabetic gastroparesis is similar to achalasia. Both conditions involve smooth muscle sphincters that fail to relax appropriately and have elevated tone. Elevated sphincter tone can prevent normal emptying of either the esophagus or the stomach. Modeling the therapeutic success in achalasia, two patients with severe diabetic gastroparesis had a dramatic improvement in symptoms after botulinum toxin injection of the pylorus (10). These preliminary results led us to initiate the current study involving eight patients with long-standing diabetes and mean insulin use of 24.4 years. All patients had failed standard medical therapy (erythromycin, metoclopramide, cisapride, domperidone) without improvement in symptoms. When asked to objectively measure their symptoms of nausea, vomiting, and abdominal pain, mean pretreatment scores were 27 of a maximum of 36. Subjectively, all eight patients stated that their symptoms greatly reduced their quality of life on a daily basis. Botulinum toxin injection of the pylorus was easily accomplished during routine endoscopy in all eight patients without any immediate or delayed side effects. Individually, all eight patients noted an improvement in symptom scores over the 12-week study period. Collectively, symptom scores decreased significantly at all follow-up visits when compared with baseline (P < 0.01). The greatest decrease occurred in the first week after botulinum toxin injection, with a smaller drop during the second week. Individually, the greatest decline in symptom scores occurred in nausea and vomiting. Total SF-36 scores did not significantly improve in the six patients who completely filled out both pre- and postinjection questionnaires, although the physical functioning score did improve (P < 0.05). This may reflect an increased ability to function due to fewer episodes of nausea and vomiting. Gastric emptying scan times were found to improve or normalize in four of eight subjects. This confirms the findings by Ezzeddine et al. (14). Although the sample size is small, this improvement is remarkable, as these patients had previously failed all other standard therapy. In addition, nearly all previously published studies that evaluated the efficacy of prokinetic agents failed to demonstrate an improvement in gastric emptying scan times. Three patients did not have an improvement in gastric emptying scan time, although all noted an improvement in their symptoms. Interestingly, one patients gastric emptying scan time increased somewhat, although, subjectively, the patient felt better, and objectively, her symptom scores declined. This discordance might reflect a delayed response to botulinum toxin, transient worsening of pylorospasm, or day-to-day variation in gastric emptying.
Several patients were surprised that, after injection therapy, they were able to gain weight and reverse a gradual trend of weight loss secondary to chronic nausea and vomiting. Three patients gained >10 pounds each, and all three of these patients required at least This study confirms the previous report by Mearin et al. (9), which showed that patients with diabetic gastroparesis have pylorospasm. In the current study, pylorospasm was reduced in all five patients who completed both antropyloric manometries. This confirms and extends the findings published in a recent case report (13). Symptom scores decreased in all five patients, whereas gastric emptying scan times improved in three patients. In contrast to current medical therapy, botulinum toxin injection of the pylorus has the unique advantage of treating a specific site within the stomach (the pylorus) that is dysfunctional. Targeted therapy with botulinum toxin injection minimizes the likelihood of systemic side effects, which commonly occurs in patients treated with oral agents. The efficacy of botulinum toxin provides insight into one of the underlying pathophysiological disorders of diabetic gastroparesispylorospasm. This may occur due to a relative imbalance between the excitatory neurotransmitter acetylcholine and the inhibitory neurotransmitter nitric oxide. A reduction in nitric oxide-containing neurons could lead to an elevated tonic state in the pylorus and, thus, delay gastric emptying. A study performed by Watkins et al. (19) demonstrated that nitric oxide plays a critical role in pyloric function and that loss of nitric oxide impedes gastric emptying. As noted previously, our trial was modeled on the therapeutic success of botulinum toxin for the treatment of achalasia, a spastic smooth muscle disorder of the LES. Historically, therapeutic options to treat achalasia were limited to balloon dilation and surgery (myotomy). Botulinum toxin injection of the LES was enthusiastically greeted as a therapeutic option given initial reports describing significant success in relieving symptoms (16,17). Over the last several years, however, an accumulating body of evidence has demonstrated that botulinum toxin injection provides long-term benefits (>12 months) in only a minority of patients (20) and is often ineffective in younger patients (21,22). Balloon dilation of the LES is generally more efficacious at providing long-term relief of symptoms (23) and is more cost-effective (24). Laparoscopic Heller myotomy is preferred by many gastroenterologists and surgeons given its long-term favorable outcome. Applying these lessons to the clinical scenario of pylorospasm in patients with diabetic gastroparesis is difficult due to a lack of clinical studies. No well-designed studies have been performed to assess the efficacy of balloon dilation of the pylorus in adults with gastroparesis. One study of 19 children demonstrated that balloon dilation of the pylorus led to complete resolution of symptoms in 11 patients and transient improvement in symptoms of up to 8 weeks in 5 patients (25). Pyloromyotomy has been shown to improve symptoms in patients with hypertrophic pyloric stenosis (26), although there are no controlled studies of pyloromyotomy in patients with diabetic gastroparesis. In addition, the underlying pathophysiology of hypertrophic pyloric stenosis is likely quite different quantitatively than diabetic pylorospasm. Our results point out that botulinum toxin injection of the pylorus can provide significant relief of symptoms over several months. The dose of botulinum toxin used in our study (200 units) was higher than that used to typically treat achalasia (100 units), as the mass of the pylorus is believed to be greater than that of the LES. Botulinum toxin injection of the pylorus may earn a place in our armamentarium of therapeutic agents for patients with mild-to-moderate diabetic gastroparesis who have failed traditional prokinetic agents (metoclopramide, erythromycin, cisapride). This therapy may prove to be most valuable in those diabetic patients with intractable nausea and vomiting who cannot tolerate oral medications and in those with persistent symptoms despite maximal medical therapy. Although our study demonstrated that patients noted an improvement in both nausea and vomiting, it is not likely that this therapy will replace the use of traditional antiemetic agents for gastroparetic patients with only mild nausea, given the expense of botulinum toxin and the need for endoscopy. Future trials will need to evaluate the long-term safety, efficacy, and cost of botulinum toxin therapy compared with balloon dilation of the pylorus, pyloromyotomy, and gastric electrical stimulation.
Summary Before botulinum toxin injection of the pylorus is adopted in clinical practice for the routine treatment of diabetic gastroparesis, we recommend that endoscopists interested in using this technique consider pooling both resources and patients to conduct a blinded, placebo-controlled trial to confirm the efficacy of this treatment. Funding agencies such as the National Institutes of Health or the American Diabetes Association should strongly consider support of such research, which has the potential to bring relief to diabetic patients suffering from gastroparesis.
Please rate any symptoms that you currently have. If the symptoms were given as numbers, then no symptoms would equal 0, mild symptoms would equal 1, moderate symptoms would equal 2, and severe symptoms would equal 3 (Table 1).
This study was funded by donations to the Marvin M. Schuster Center for Digestive and Motility Disorders and by unrestricted educational grants (to B.E.L. [CERT grant from Johns Hopkins and Allergan]).
P.J.P. is a paid consultant for Allergan. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Received for publication March 26, 2004. Accepted for publication June 28, 2004.
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