Pharmacotherapy of gastroparesis

Small Bowel Dysmotility, Pseudoobstruction, and Functional Correlation with Histopathology: Lessons Learned

PURPOSE OF REVIEW

Small bowel dysmotility is a broad heterogeneous term that encompasses a wide range of gastrointestinal disorders resulting from abnormal gut motility. Chronic intestinal pseudo-obstruction (CIPO) is a severe, rare, and complex small bowel motility disorder at the extreme end of this spectrum. It is characterized by failure of the intestinal tract to propel contents, which results in signs and symptoms of bowel obstruction albeit in the absence of any obstructive lesion(s). In this article, we discuss up-to-date diagnostic techniques, management options, and histopathological findings in CIPO.

RECENT FINDINGS

We will emphasize the latest diagnostic methodologies and therapeutic options as well as enteric histopathologic abnormalities in patients with CIPO. CIPO continues to be a clinical challenge. Several novel pharmacological agents hold promise including gastrointestinal hormone agonists and prokinetics. Furthermore, histopathologic findings may help guide therapy and provide further prognostic significance. At present, nutritional support, symptom management, and avoidance of long-term complications are the mainstay of treatment in CIPO.

Does the Ileal Brake Contribute to Delayed Gastric Emptying After Pancreatoduodenectomy?

Delayed gastric emptying (DGE) represents a significant cause for morbidity following pancreatoduodenectomy (PD). At a time when no specific and universally effective therapy exists to treat these patients, elucidating other potential (preventable or treatable) mechanisms for DGE is important. The aim of the manuscript was to test the hypothesis that ileal brake contributes to DGE in PD patients receiving jejunal tube feeding by systematically reviewing experimental and clinical literature. A series of clinically relevant questions were framed related to the potential role of the ileal brake in development of DGE post-PD and formed the basis of targeted literature searches. A comprehensive search of major reference databases from January 1980 to June 2015 was carried out which included human and animal studies. The ileal brake is a feedback loop neurally mediated by the vagus and sympatho-adrenergic pathways and hormonally by gut peptides including glucagon-like peptide-1, peptide YY (PYY), and neurotensin. The most potent stimulus for this inhibitory reflex is intra-ileal fat. There is evidence to indicate the role of an inhibitory reflex (on gastric emptying) mediated by PYY and CCK which, in turn, are stimulated by nutrient delivery into the distal small intestine providing indirect support to the role of ileal brake in post-PD DGE. The ileal brake is a likely factor contributing to DGE post-PD. While there has been no study to directly test this hypothesis, there is compelling indirect evidence to support it. Designing a trial that would answer such a question appears to be the most appropriate way forward.

End of the road for a dysfunctional end organ: laparoscopic gastrectomy for refractory gastroparesis

INTRODUCTION

Gastroparesis is a functional disorder resulting in debilitating nausea, esophageal reflux, and abdominal pain and is frequently refractory to medical treatment. Therapies such as pyloroplasty and neurostimulators can improve symptoms. When medical and surgical treatments fail, palliative gastrectomy is an option. We examined outcomes after gastrectomy for postoperative, diabetic, and idiopathic gastroparesis.

METHODS

A prospective database was queried for gastrectomies performed for gastroparesis from 1999 to 2013. Primary outcomes were improvements in pre- versus postoperative symptoms at last follow-up, measured on a five-point scale. Secondary outcome was operative morbidity.

RESULTS

Thirty-five patients underwent laparoscopic total or near-total gastrectomies for postoperative (43 %), diabetic (34 %), or idiopathic (23 %) gastroparesis. Antiemetics and prokinetics afforded minimal relief for one third of patients. There were no mortalities. Six patients suffered a leak, all treated with surgical reintervention. With a median follow-up of 6 months, nausea improved or resolved in 69 %. Chronic abdominal pain improved or resolved in 70 %. Belching and bloating resolved for 79 and 89 %, respectively (p < 0.01).

CONCLUSIONS

Regardless of etiology, medically refractory gastroparesis can be a devastating disease. Near-total gastrectomy can ameliorate or relieve nausea, belching, and bloating. Chronic abdominal pain commonly resolved or improved with resection. Despite attendant morbidity, gastrectomy can effectively palliate symptoms of gastroparesis.

Neurochemical mechanisms and pharmacologic strategies in managing nausea and vomiting related to cyclic vomiting syndrome and other gastrointestinal disorders

Nausea and vomiting are common gastrointestinal complaints which could be triggered by stimuli in both the peripheral and central nervous systems. They may be considered as defense mechanisms when threatening toxins/agents enter the gastrointestinal tract or there is excessive retention of gastrointestinal contents due to obstruction. The pathophysiology of nausea and vomiting is complex and much still remains unknown. Therefore, treatments are restricted or ineffective in many cases. Nausea and vomiting with functional etiologies including cyclic vomiting syndrome are challenging in gastroenterology. In this article, we review potential pathways, neurochemical transmitters, and their receptors which are possibly involved in the pathophysiology of nausea and vomiting including the entity cyclic vomiting syndrome.

Gastric electrical stimulation with Enterra therapy improves symptoms of idiopathic gastroparesis

BACKGROUND

Gastric electrical stimulation (GES) is a therapeutic option for intractable symptoms of gastroparesis (GP). Idiopathic GP (ID-GP) represents a subset of GP.

AIMS

A prospective, multicenter, double-blinded, randomized, crossover study to evaluate the safety and efficacy of Enterra GES in the treatment of chronic vomiting in ID-GP.

METHODS

Thirty-two ID-GP subjects (mean age 39; 81% F, mean 7.7 years of GP) were implanted with GES. The stimulator was turned ON for 1½ months followed by double-blind randomization to consecutive 3-month crossover periods with the device either ON or OFF. ON stimulation was followed in unblinded fashion for another 4.5 months. Twenty-five subjects completed the crossover phase and 21 finished 1 year of follow-up.

KEY RESULTS

During the unblinded ON period, there was a reduction in weekly vomiting frequency (WVF) from baseline (61.2%, P < 0.001). There was a non-significant reduction in WVF between ON vs OFF periods (the primary outcome) with median reduction of 17% (P > 0.10). Seventy-five percent of patients preferred the ON vs OFF period (P = 0.021). At 1 year, WVF remained decreased (median reduction = 87%, P < 0.001), accompanied by improvements in GP symptoms, gastric emptying and days of hospitalization (P < 0.05).

CONCLUSIONS & INFERENCES

(i) In this prospective study of Enterra GES for ID-GP, there was a reduction in vomiting during the initial ON period; (ii) The double-blind 3-month periods showed a non-significant reduction in vomiting in the ON vs OFF period, the primary outcome variable; (iii) At 12 months with ON stimulation, there was a sustained decrease in vomiting and days of hospitalizations.

The addition of pyloroplasty as a new surgical approach to enhance effectiveness of gastric electrical stimulation therapy in patients with gastroparesis

BACKGROUND

Improvement of gastroparesis (GP) symptoms has been documented in patients treated with gastric electrical stimulation (GES), but acceleration of gastric emptying (GET) is unpredictable. The aim of our study was to evaluate the advantage of adding surgical pyloroplasty (PP) to GES for improvement of GET and control of symptoms in diabetes mellitus (DM), idiopathic (ID), and postvagotomy (P-V) GP.

METHODS

A total of 49 (17 - DM, 9 - ID, 23 - P-V) consecutive GP patients: 38 female; mean age 42 (21-73 years); mean weight 158 lbs (102-245), underwent GES implantation, and 26 (53%) additionally received PP. Total Symptoms Score, 4-h GET, adverse events (AEs), and days of hospitalizations were captured at baseline and at the last visit.

KEY RESULTS

The mean follow-up was 7 months. Total Symptoms Score in patients who received Enterra and PP or GES alone significantly improved compared to their baseline scores (P < 0.001). GET improved by 64% at 4 h (P < 0.001) in patients with Enterra and PP, compared to 7% observed after GES therapy alone (ns). The most impressive acceleration of GET was seen in the P-V group, who received both therapies (P = 0.004) and 8 (60%) of them normalized GET. No AEs accompanied the addition of PP to the Enterra surgery.

CONCLUSIONS & INFERENCES

(i) In drug-refractory GP the addition of PP to GES substantially accelerated GET; (ii) The GET response in P-V group was the most impressive; (iii) Significant symptom reductions were achieved by both procedures; and (iv) PP added to GES may sustain better long-term symptoms control particularly in the P-V setting.

Prokinetics in diabetic gastroparesis

Within the last 50 years, diabetic gastroparesis has become a well recognized complication of type 1 and type 2 diabetes. It is a syndrome characterized by abnormal gastric function, resulting in delayed emptying of the stomach in the absence of any evident mechanical obstruction, predominantly manifested by early satiety, postprandial fullness, nausea, vomiting, and weight loss. The past five years have shown significant advances in its pathophysiology and in new diagnostic tests. Prokinetic medications remain the therapeutic focus for improving clinical symptoms of gastroparesis through enhanced gastric emptying. This article summarizes the present knowledge of prokinetics, with emphasis on medications currently available, as well as drugs under clinical investigation, including some agents in advanced clinical trials that are likely to be used in the treatment of diabetic gastroparesis in the future. These include the ghrelin agonists and newer 5-HT4 agonists devoid of cardiac side effects.

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.

Real-time ultrasonographic evaluation of canine gastric motility in the postprandial state

Gastric motility is affected by several pathological conditions which may induce upper gastrointestinal clinical symptoms. The pathogenesis of canine gastric motility disorders is poorly understood because of methodological limitations. This study aimed at establishing a simple method for evaluating postprandial gastric motility in dogs. Gastric motility was ultrasonographically assessed in 7 healthy beagles using a technique previously described in humans. The motility index (MI), an indicator of gastric antral motility, was calculated by measuring the area of the gastric antrum in both a contracted and relaxed phase and by counting the number of contractions. The MI was measured every 30 min for 3 hr after feeding and compared with gastric emptying as assessed by a (13)C-octanoic acid breath test. The MI at 30 min had the lowest variability in the 7 dogs (mean SD, 9.77 ± 0.42; coefficient of variance, 4.25%), and a significant correlation was observed with gastric emptying coefficient (R(2)=0.8126, P=0.005) and half-emptying time (R(2)=0.654, P=0.027). When atropine was administered, a significant decrease in the MI at 30 min was observed compared with the control (9.77 ± 0.42 vs. 5.19 ± 0.22, P=0.0003). In conclusion, evaluation of the MI at 30 min is suitable for assessing gastric motility and enables us to assess gastric motility simply in a short time. By using this method, further studies for the pathogenesis of canine gastric motility disorders are warranted.

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.

Interstitial cells of Cajal, the Maestro in health and disease

Interstitial cells of Cajal (ICC) are important players in the symphony of gut motility. They have a very significant physiological role orchestrating the normal peristaltic activity of the digestive system. They are the pacemaker cells in gastrointestinal (GI) muscles. Absence, reduction in number or altered integrity of the ICC network may have a dramatic effect on GI system motility. More understanding of ICC physiology will foster advances in physiology of gut motility which will help in a future breakthrough in the pharmacological interventions to restore normal motor function of GI tract. This mini review describes what is known about the physiologic function and role of ICCs in GI system motility and in a variety of GI system motility disorders.

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.