[COVID-19 and endoscopy services]

In 2020, the coronavirus pandemic initially led to a significant decrease in elective endoscopic examinations in Germany. The main reasons for this were the hard lockdown and the lack of personal protective equipment (PPE) and testing procedures. Since then, international recommendations from professional societies on infection control in endoscopy have been published. The extent to which these have been implemented in Germany is unclear: during the 2nd and 3rd waves in 2020/2021, most endoscopy units remained open and the level of adherence to international protection guidelines was high. A uniform "standard procedure" has not yet been published. The exact role and effectiveness of testing procedures to protect patients and staff during endoscopy was unknown, and reliable figures on staff and patient infections acquired/transmitted in endoscopy units in Germany were lacking. Thus, the most important finding of this work is the determined rate of coronavirus disease 2019 (COVID-19) in endoscopy facilities. The data show that the infection rate among staff in German clinics and practices in early 2021 averaged up to 5%; most of these were acquired in the private setting. Clinics with gastroenterological endoscopy units had significantly higher infection rates (10%) than, for example, dental and otolaryngology practices. This result indicates the need for continued PPE efforts. The most important factors for infection safety are fully vaccinated (or recovered) staff and patients, a decreasing prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the use of PPE and-although controversial-the consistent use of screening tests.

[EUS-FNA: how to improve biopsy results? An evidence based review]

Endosonography with fine-needle aspiration biopsy (EUS-FNA) has become a widespreadly available clinical tool to diagnose numerous different lesions in humans. EUS-FNA is frequently used for tissue-based diagnoses such as lymphatic diseases (ranging from tuberculosis / sarcoidosis to malignant lymphoma) or solid tumors (such as pancreatic carcinoma, neuroendocrine tumors, sub-epithelial gastrointestinal tumors and others). Outcomes of EUS-FNA results, however, vary which is caused by several different factors ranging from experience of the endoscopist over technical factors such as use of stylet or suction for puncture through the skills of the cyto-pathologist who takes care of the specimen obtained by EUS-FNA. Though introduced since more than 20 years ago EUS-FNA has still not yet been perfectionized and several issues remain controversial among endoscopist. These issues include needle size and type (FNA versus TNB needles), use of a stylet and suction for FNA sampling, pure cytologic assessment versus cyto-histologic techniques, grading of the investigator´s and pathologist´s experience and improvement of EUS training for novices. In this report we briefly review the actual literature and summarize the available evidence on some controversely discussed issues. The results support the view that use of a stylet rarely aids to increase the amount of tissue obtained during EUS-FNA, whereas use of suction can be helpful in certain situations. Novel cutting needles may potentially improve number and size of core biopsies that can be rendered for special histologic tissue processing techniques. An in-room-cytopathologist not necessarily improves outcome of EUS-FNA results but may have a role during build-up of EUS units to become more successful. EUS-FNA education requires skilled endoscopists on both sides and can presumably be improved by objective testing of practical expertise by peer review and introducing objective sampling parameters. Novel techniques and equipment are about to evolve in the near future.

A randomised phase II trial of the Polo-like kinase inhibitor BI 2536 in chemo-naïve patients with unresectable exocrine adenocarcinoma of the pancreas - a study within the Central European Society Anticancer Drug Research (CESAR) collaborative network

BACKGROUND

BI 2536, a novel Polo-like kinase 1 inhibitor, was assessed in patients with unresectable advanced exocrine adenocarcinoma of the pancreas.

METHODS

The study employed a two-stage design. Randomised first-line patients received BI 2536 200 mg on day 1 (n=43) or 60 mg on days 1-3 (n=43) every 21 days. Recruitment of second-line patients was planned for a second stage dependent on an interim analysis demonstrating ≥ 2 responses in the first 18 evaluable patients following 12 weeks of treatment and/or tumour control ≥ 12 weeks in 5 patients per schedule. Primary end point was objective response rate (ORR).

RESULTS

By independent review, ORR was 2.3% (all partial) and 24.4% had stable disease as confirmed best response. The second stage was not initiated. Median overall and progression-free survivals were 149 (95% confidence interval (CI), 91-307) and 46 days (95% CI, 44-56). Most common drug-related adverse events were neutropenia (37.2%), leukopenia (29.1%), fatigue (29.1%) and nausea (22.1%); most common grade 3/4-related events were neutropenia (36.0%), leukopenia (27.9%) and thrombocytopenia (8.1%).

CONCLUSION

Given the low ORR and poor survival, further development of BI 2536 monotherapy is not warranted in this population.

KRAS mutation in metastatic pancreatic ductal adenocarcinoma: results of a multicenter phase II study evaluating efficacy of cetuximab plus gemcitabine/oxaliplatin (GEMOXCET) in first-line therapy

BACKGROUND

Genetic alterations within the epidermal growth factor receptor (EGFR) pathway, including KRAS mutations, have been demonstrated to be associated with response to EGFR inhibitors like cetuximab in colorectal cancers. Mutations in the KRAS gene have been found in 70-90% of pancreatic cancers. Unfortunately, the addition of cetuximab to chemotherapy did not increase response or survival in patients with advanced pancreatic cancer in phase II and phase III studies. The aim of this study was to evaluate the relationship between KRAS mutations and response or survival in patients with metastatic pancreatic cancer treated with cetuximab plus chemotherapy.

METHODS

Within a multicenter phase II trial, 64 patients with metastatic pancreatic cancer were treated with cetuximab in combination with gemcitabine and oxaliplatin until disease progression. Analyses of the EGFR pathway, including KRAS mutations, could be performed in 25 patients. Analyses were carried out following microdissection of the tumor.

RESULTS

Fourteen (56%) of the 25 patients examined harbored a point mutation in codon 12 of the KRAS gene. No differences between the groups were noted in median progression-free survival (104 days in KRAS wild-type patients vs. 118 days in patients with KRAS mutations). Overall survival was longer in wild-type patients compared to patients with KRAS mutations (263 vs. 162 days), but the difference did not reach statistical significance. A further analysis of our clinical phase II trial showed that the presence of a rash was significantly correlated with overall survival.

CONCLUSIONS

KRAS mutation in codon 12 may be associated with reduced survival compared to KRAS wild type. The role of KRAS mutations for cetuximab therapy in pancreatic cancer warrants further investigation in larger trials to exclude an epiphenomenon. Furthermore, the development of a rash is indicative of clinical benefit.

Prospective comparison of endoscopic ultrasound-guided fine-needle aspiration and surgical histology in upper gastrointestinal submucosal tumors

STUDY AIM

To assess the accuracy of ultrasound-guided fine-needle aspiration biopsy in the differential diagnosis of gastrointestinal stroma cell tumors (GIST) from other submucosal tumors, using both cytology and histology.

PATIENTS AND METHODS

We conducted a prospective study from May 2005 to September 2008 in all patients presenting with upper gastrointestinal submucosal tumors. Only patients in whom surgical resection was carried out were included in the final analysis. In cases of mesenchymal tumor, immunocytochemistry was attempted for further differentiation between GIST and non-GIST. Surgical histopathology served as the gold standard.

RESULTS

A total of 47 patients were analyzable, with a final histologic diagnosis of 35 mesenchymal tumors. Sufficient tissue for conventional cytologic diagnosis was obtained only in the 35 patients with mesenchymal tumors; in this subgroup, immunocytochemistry was possible in 46 %. If and only if enough material was available for immunocytochemistry, the sensitivity for (correct recognition of) GIST tumors was 93 %. In all 12 patients with nonmesenchymal tumors and lesions, cytology was nondiagnostic and the diagnosis had to be based on clinical suspicion and the appearance on endoscopy and endoscopic ultrasound (EUS). On an intention-to-diagnose basis, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) had a positive predictive value for mesenchymal tumors of 100 %, but no value for the diagnosis of other lesions; using immunocytochemistry, a GIST tumor was recognized among the mesenchymal tumors with a sensitivity of 58 % and a specificity of 8 %.

CONCLUSIONS

EUS-FNA-based cytology is safe and has only limited value for the differential diagnosis of submucosal tumors, mainly because insufficient material is harvested. Better tissue acquisition techniques are necessary for better differential diagnosis.

Cetuximab plus gemcitabine/oxaliplatin (GEMOXCET) in first-line metastatic pancreatic cancer: a multicentre phase II study

Targeting the epidermal growth factor receptor pathway in pancreatic cancer seems to be an attractive therapeutic approach. This study assessed the efficacy of cetuximab plus the combination of gemcitabine/oxaliplatin in metastatic pancreatic cancer. Eligible subjects had histological or cytological diagnosis of metastatic pancreatic adenocarcinoma. The primary end point was response according to RECIST. Patients received cetuximab 400 mg m⁻² at first infusion followed by weekly 250 mg m⁻² combined with gemcitabine 1000 mg m⁻² as a 100 min infusion on day 1 and oxaliplatin 100 mg m⁻² as a 2-h infusion on day 2 every 2 weeks. Between January 2005 and August 2006, a total of 64 patients (22 women (34%), 42 men (66%); median age 64 years (range 31–78)) were enrolled at seven study centres. On October 2007, a total of 17 patients were alive. Sixty-two patients were evaluable for baseline and 61 for assessment of response to treatment in an intention-to-treat analysis. Six patients had an incomplete drug combination within the first cycle of the treatment plan (n=4 hypersensitivity reactions to the first cetuximab infusion, n=2 refused to continue therapy). Reported grade 3/4 toxicities (% of patients) were leukopaenia 15%, anaemia 8%, thrombocytopaenia 10%, diarrhoea 7%, nausea 18%, infection 18% and allergy 7%. Cetuximab-attributable skin reactions occurred as follows: grade 0: 20%, grade 1: 41%, grade 2: 30% and grade 3: 10%. The intention-to-treat analysis of 61 evaluable patients showed an overall response rate of 33%, including 1 (2%) complete and 19 (31%) partial remissions. There were 31% patients with stable and 36% with progressive disease or discontinuation of the therapy before re-staging. The presence of a grade 2 or higher skin rash was associated with a higher likelihood of achieving objective response. Median time to progression was 118 days, with a median overall survival of 213 days. A clinical benefit response was noted in 24 of the evaluable 61 patients (39%). The addition of cetuximab to the combination of gemcitabine and oxaliplatin is well tolerated but does not increase response or survival in patients with metastatic pancreatic cancer.

Systematic review: the safety and tolerability of pharmacological agents for treatment of irritable bowel syndrome--a European perspective

AIM

To use an evidence-based approach to evaluate the safety and tolerability of the treatments available for irritable bowel syndrome (IBS), or in clinical development, in Europe. A separate review appraises the evidence for the efficacy of these therapies.

METHODS

A literature search (for 1980 to 2005) was completed for all relevant clinical trial data and other articles which included safety information on the use of pharmacological IBS therapies. Clinical trials were scored according to the level of safety information, and adverse event incidence reported when possible.

RESULTS

The tolerability of many of the agents used to treat IBS in Europe is poorly understood. However, serotonergic agents, such as tegaserod and alosetron, which are currently unavailable in Europe, have undergone rigorous assessment in IBS and their benefits have been established. Following initial marketing of alosetron for use in patients with IBS with diarrhoea, concerns about severe constipation and ischaemic colitis resulted in restriction of its use to women with severe IBS symptoms. This highlights the importance of post-marketing surveillance and post-marketing studies in refining the therapeutic indication of new IBS therapies, which will help to identify appropriate recipients for the drug and establish the impact of adverse reactions in clinical practice.

CONCLUSIONS

There is a significant lack of data on the safety and tolerability of the therapies currently used routinely to treat IBS in Europe. The newer agents have undergone rigorous assessment, such that their benefits and risks in treating IBS are established. Defining their place among the spectrum of available therapies remains challenging when the benefits and risks of the older treatments are so poorly characterized.

A randomized phase III trial in patients with advanced adenocarcinoma of the stomach receiving first-line chemotherapy with fluorouracil, leucovorin and oxaliplatin (FLO) versus fluorouracil, leucovorin and cisplatin (FLP)

LBA4016

Background: Cisplatin-based chemotherapy is a standard option in advanced gastric cancer. However, treatment results have been unsatisfactory so far, with a time to progression (TTP) of 3 to 4 months and an overall survival (OS) of 6 to 9 months. In addition, treatment regimens are too intense and toxicity is considerable. The aim of this 2-arm randomized trial was to determine whether FLO prolongs TTP and reduces toxicity as compared to FLP. Methods: Patients (pts) were randomized to receive FLO: F 2600 mg/m2 24 h infusion, L 200 mg/m2, and oxaliplatin 85 mg/m2, every two weeks or FLP: F 2000 mg/m2 24 h infusion, L 200 mg/m2, weekly, and cisplatin 50 mg/m2, every two weeks. The primary end point was TTP. Main secondary endpoints included toxicity, time to treatment failure (TTF), and OS. Based on a planned sample size of 218 pts, the trial was designed to have an 80% power to detect an improvement in median TTP from 3.5 to 5.0 months (1-sided log-rank test; significance level 0.05). Results: 220 pts (FLO/FLP, 112/108) were randomized between Aug 2003 and Jan 2006. Median age was 64 yrs and median ECOG was 1. 162 pts (FLO, 80; FLP, 81) had disease progression and 25 pts (FLO, 18; FLP, 8) are still under treatment. Median TTP was 5.7 months for FLO and 3.8 months for FLP (log-rank p = 0.081, Wilcoxon p = 0.019). Median TTF was 5.3 months for FLO and 3.1 months for FLP (log-rank p = 0.028). Response to FLO (34%) was superior to FLP (27%), with 15% and 30% of pts having disease progression as best response to FLO and FLP, respectively (chi-square for trend p = 0.012). Median treatment duration was 4.3 months with FLO and 3 months with FLP. FLO was associated with significantly less NCI-CTC grade 1–4 leukopenia, nausea, alopecia, fatigue, and renal toxicity and FLP was associated with significantly less peripheral neuropathy (chi-square for trend p < 0.05). Severe adverse events related to treatment were less frequent with FLO (8.9%) as compared to FLP (18.6%; p = 0.046). Conclusions: FLO reduced toxicity and improved efficacy as compared to FLP. This leads us to consider FLO for future studies in combination with targeted drugs to further improve the outcome of pts with gastric cancer.

No significant financial relationships to disclose.

Pseudo-affective visceromotor responses and HPA axis activation following colorectal distension in rats with increased cholinergic sensitivity

We analysed visceromotor (VMR) and corticosterone responses to colorectal stimuli under control conditions and following acoustic stress in rats selectively bred for increased sensitivity to cholinergic agonists, the Flinders Sensitive Line (FSL) rats, compared with Flinders Resistant Line (FRL) rats. FSL rats demonstrated a significant VMR response at the smallest distension pressure, whereas no response was evident in FRL controls. FSL rats also demonstrated enhanced VMR responses at both larger distension levels compared with FRL rats. Colorectal distension (CRD) produced significant increases in serum corticosterone levels, which were comparable in FRL and FSL. Noise stress induced divergent corticosterone responses in FRL and FSL, but did not affect VMR to CRD in either group. These data suggest that FSL rats show altered VMR responses to CRD and disturbed hypothalamic-pituitary-adrenal axis responses to acute stress.

[Symptomatic biliary stones at the lower end of the common duct following hepaticoduodenostomy]

A 66-year-old patient developed episodes of severe pain due to recurrent cholangitis and pancreatitis. 2 years prior to this referral the patient had undergone an end-to-side hepaticoduodenostomy and a cholecystectomy because of choledocholithiasis and obstructive jaundice. 20 years previously a Billroth II operation had been carried out for the treatment of ulcer disease. Since the hepaticoduodenostomy the patient has suffered from recurrent epigastric pain, nausea and postprandial vomiting. An oedematous pancreatitis following a recurrent chronic cholangitis was assumed. As the intrahepatic biliary ducts appeared to be normal on radiological studies and hepatobiliary scintigraphy showed a downright transit of the tracer, recurrent cholangitis appeared at first to be a rather unlikely explanation. However, follow-up MRI and MRCP showed large calculi at the lower end of the common duct, which was also enlarged up to 1 cm. For this reason an open duodenotomy with subsequent papillosphincterotomy and retrograde choledochoscopy was carried out. The diagnosis was confirmed hereby and all calculi were removed during the operation. Since then the patient has been free of symptoms and complaints. This case shows that remaining calculi at the lower end of the common bile duct can cause severe clinical problems. Therefore the bile ducts should be inspected endoscopically and stones removed prior to, or during the primary operation.

Klinische Wertigkeit der endosonographischen Feinnadelpunktion bei Erkrankungen des oberen Gastrointestinaltrakts und Mediastinums

BACKGROUND

Endoscopic ultrasound (EUS)-guided fine-needle aspiration biopsy (EUS-FNA) is increasingly used for the diagnosis of malignant and benign disease in the region of the upper GI tract. We prospectively investigated the clinical accuracy and safety of this method in unselected patients under routine conditions.

PATIENTS AND METHODS

101 consecutive patients (median 61.5 years; 56 female) were enrolled in the study, in whom a total of 106 tissue biopsies were obtained by using EUS-FNA. Major indications for EUS-FNA were suspicious lesions located in the mediastinum, esophagus, stomach, pancreas, liver, biliary system, adrenals or retroperitoneum. A longitudinal echoendoscope (HITACHI FG-34UX) equipped with a standard 22G -aspiration needle was used. The aspirated specimens were analyzed further by using standard cytology and/or histology. Lymph-node biopsies were additionally subjected to flow-cytometry (FACS-light-chain restriction). Surgery was used for reference (where available). In the remaining cases the final diagnosis obtained by the clinical course and all available imaging and histologic informations (ultrasound, CT, MRT) was used for reference.

RESULTS

EUS-FNA caused no serious complications. In 6/106 specimen (5.6 %) no sufficient cell material could be aspirated. In the remaining 100 specimens EUS-FNA reached an overall sensitivity of 78 % and a specificity of 100 %, while the accuracy was 89 % and the positive and negative predictive values were 100 % and 81 %, respectively. The greatest diagnostic accuracy was achieved in mediastinal and retroperitoneal lesions, while the accuracy of EUS-FNA in pancreatic lesions and perigastric lymph nodes was distinctly smaller (<80 %). Addition of FACS studies in patients with suspected malignant lymphoma increased the diagnostic accuracy in the small number of patients included in the study.

CONCLUSION

EUS-FNA improves the tissue-based diagnosis of suspicious lesions in locations that are difficult to access (e. g., posterior mediastinum). EUS-FNA is safe, while its diagnostic accuracy is relatively high. Our preliminary data suggest that flow-cytometry may improve the fine-needle based diagnosis of non-Hodgkin s lymphoma, which should be further investigated.

[Diagnostic utility of capsule endoscopy in occult gastrointestinal bleeding]

BACKGROUND AND OBJECTIVE

The video-capsule endoscopy (CE) of the small intestine is a novel innovative procedure for outpatient use that can detect even small lesions of the mucosa of the small intestine. Aim of this retrospective clinical study was to evaluate the diagnostic value of CE in a clinical routine setting.

PATIENTS AND METHODS

Between July 2001 and October 2002 we investigated 42 patients with suspected gastrointestinal bleeding by CE. In all patients, the previous upper and lower endoscopy work-up was normal. In some cases additional procedures such as bloodpool scintigraphy, angiography, small-bowel enteroclysis or push-enteroscopy were performed.

RESULTS

CE detected relevant pathological findings in 23 out of 42 Patients (55 %). The majority of findings in the CE consisted of angiodysplasia (n = 16), ulcer and haemorrhagical erosions (n = 10), one Ulcus Dieulafoy and additional polyps of the small intestine (n = 2). In 4 cases an inflammatory small-bowel disease was detected. These findings could be confirmed by Re-endoscopy. The information provided was helpful to direct further diagnostic and treatment options. In 14 cases (33 %) CE-findings steered additional diagnostic and therapeutic steps. We conclude that CE is safe and has a high diagnostic yield.

CONCLUSION

M2A video CE is likely to become an integral part of the algorithm of diagnostic of occult gastrointestinal bleeding after exclusion of other causes of anemia and negative upper and lower endoscopy work-up.

Diagnosis of hepatocellular carcinoma (HCC) in a high-risk patient by using transgastric EUS-guided fine-needle biopsy (EUS-FNA)

Hepatocellular carcinoma (HCC) is the most common primary malignancy arising within the liver and most often affects individuals with chronic hepatitis and/or liver cirrhosis. Patients often present at an advanced stage of disease or with poor liver function, thus limiting treatment options and resulting in a poor prognosis of the disease. Therefore, an early tissue-based diagnosis of HCC is necessary to direct further work-up and treatment. We present the case of a 70-year-old man with alcoholic cirrhosis at stage Child C, in whom a tumor nodule was found incidentally within the left lobe of the liver. Percutaneous biopsy was deemed too dangerous because a deteriorated liver function with coagulopathy was present, and a significant amount of ascites surrounded the small cirrhotic liver. To obtain a conclusive diagnosis, we performed transgastric fine-needle biopsy of the tumor under direct endosonographic guidance (EUS-FNA) without complications. Cytologic examination confirmed the presence of a well differentiated HCC. Based on this finding, super-selective CT-guided angiography and chemoembolization were subsequently performed without complications and the patient remained free of tumor relapse for the 8 months of surveillance. We conclude that EUS-guided fine-needle biopsy and cytologic examination represent a reliable alternative for tissue sampling in HCC, particularly in selected high-risk patients such as those with poor liver function and coagulation disorders; this should be assessed in prospective clinical trials.

Endoscopic ultrasound-guided fine-needle aspiration biopsy of liver lesions: histological and cytological assessment

BACKGROUND AND STUDY AIMS

EUS-guided fine-needle aspiration biopsy (EUS-FNA) is used increasingly for the diagnosis of mediastinal, biliopancreatic, and gastric tumors. However, little is known about EUS-FNA in hepatic lesions and the best method for tissue analysis. We assessed EUS-FNA combined with histological and cytological evaluation in selected patients.

PATIENTS AND METHODS

41 patients (66 +/- 7 years) were prospectively studied, 33 of whom had clinical findings suggestive of liver malignancies. Selection for EUS-FNA was based on an increased risk of bleeding from percutaneous biopsy (coagulopathy, cirrhosis, ascites, aspirin intake; n = 15), presence of small liver tumors < 2 cm (n = 12), or liver lesions found incidentally (n = 14). Transgastric EUS-FNA of lesions located in accessible liver segments was performed using the Hitachi FG-34UX longitudinal echo endoscope and a 22-G aspiration needle. Specimens were submitted separately for standard cytological and histological evaluation. In the case of malignancies, findings at surgery with histological examination, endoscopy, or computed tomography (CT)-guided biopsy of the primary cancer served as reference results (n = 33), while in benign disorders, a combination of imaging studies (Magnetic Resonance Tomography <MRT>, scintigraphy) and the clinical follow-up, as summarized in the physician's report, was used as reference.

RESULTS

EUS-FNA provided appropriate biopsy specimens in 40/41 patients. It was not possible to aspirate sufficient material in one patient. On average, 1.4 needle passes were necessary to obtain sufficient amounts of tissue. With regard to malignancy, the combination of histological and cytological examination had a sensitivity of 94%, specificity of 100%, negative predictive value (NPV) of 78%, and positive predictive value (PPV) of 100%. Tissue diagnoses were in agreement in 27/41 patients (65%). In the remaining patients, only the cytological examination identified six lesions correctly, while the histological assessment was correct in another seven patients. Malignant lesions were correctly identified by cytology in 24/33 (73%) patients, while histology alone was diagnostic for malignancy in 27/33 (82%) patients. When both modalities were combined, 31 out of 33-malignancies (94%) were correctly diagnosed. Minor complications occurred in two patients and consisted of self-limiting local bleeding.

CONCLUSIONS

EUS-FNA of liver tumors is a powerful, reliable, and safe procedure for the diagnosis of malignant liver lesions. Optimal diagnostic results are achieved by combining cytological with histological assessment. Hence, EUS-FNA is an alternative to percutaneous biopsy, particularly in patients at risk of bleeding or with small lesions of the liver.

Visualization of anatomical structures of epigastric organs by use of automatically segmented 3-D ultrasound image volumes--first results

The detection and the staging of tumors and their metastases in parenchymatous organs of the epigastric organs today is improved by the enormous increase of imaging system's efficiency. For an increasing number of findings, which shall be dissected in intention to cure, the feasibility of diagnostics and therapy-planning based on sonograms was investigated. In 3-D US image volumes of approx. 20 patients, characteristic anatomical structures (e.g., vessels, abscesses, tumors) were detected by specifically adapted automatic computer-based segmentation and visualized. The detection of pathological findings, their quantification and their spatial assignment to anatomical main structures was essentially simplified by 3-D image acquisition and 2-D and 3-D visualization of segmented images.

Endoscopically assisted video capsule endoscopy of the small bowel in patients with functional gastric outlet obstruction

Since the introduction in 2001 of M2A video capsule imaging of the small bowel in humans, this technique has been used increasingly in patients with disorders of the small bowel. In particular the assessment of small obscure gastrointestinal bleeding sources and the detection of shallow inflammatory lesions in the small bowel, have been greatly facilitated by this novel imaging procedure. We report two cases of patients with obscure gastrointestinal bleeding, in whom normal passage of the capsule through the antroduodenal junction was inhibited. This was because of delayed gastric emptying in both patients, which was presumably caused by functional impairment of pyloric motility. To facilitate capsule transport into the small bowel, after swallowing the capsule each patient underwent unsedated upper gastrointestinal endoscopy during which the capsule was grasped with a polypectomy snare, directly transported through the pylorus, and finally released upon arrival in the second portion of the duodenum. Capsule recordings revealed the source of bleeding in both patients and their medical or surgical treatment was subsequently escalated. Capsule imaging of the small bowel facilitated by esophagogastroduodenoscopy (EGD) is safe, and can be applied when patients have functional disorders of pyloric motility.

Cardiac autonomic function and oesophageal acid sensitivity in patients with non-cardiac chest pain

BACKGROUND

Acid reflux can elicit non-cardiac chest pain (NCCP), possibly through altered visceral sensory or autonomic function. The interactions between symptoms, autonomic function, and acid exposure are poorly understood.

AIM

To examine autonomic function in NCCP patients during exposure to oesophageal acid infusion.

SUBJECTS AND METHODS

Autonomic activity was assessed using power spectral analysis of heart rate variability (PSHRV), before and during oesophageal acidification (0.1 N HCl), in 28 NCCP patients (40.5 (10) years; 13 females) and in 10 matched healthy controls. Measured PSHRV indices included high frequency (HF) (0.15-0.5 Hz) and low frequency (LF) (0.06-0.15 Hz) power to assess vagal and sympathetic activity, respectively.

RESULTS

A total of 19/28 patients had angina-like symptoms elicited by acid. There were no significant manometric changes observed in either acid sensitive or insensitive patients. Acid sensitive patients had a higher baseline heart rate (82.9 (3.1) v 66.7 (3.5) beats/min; p<0.005) and lower baseline vagal activity (HF normalised area: 31.1 (1.9)% v 38.9 (2.3)%; p< 0.03) than acid insensitive patients. During acid infusion, vagal cardiac outflow increased (p<0.03) in acid sensitive but not in acid insensitive patients.

CONCLUSIONS

Patients with angina-like pain during acid infusion have decreased resting vagal activity. The symptoms elicited by perception of acid are further associated with a simultaneous increase in vagal activity in keeping with a vagally mediated pseudoaffective response.

Endoscopic ultrasonography (EUS) and fine-needle aspiration (FNA) cytology for diagnosis of chronic pancreatitis

BACKGROUND AND STUDY AIMS

Previous studies have shown that endoscopic ultrasonography (EUS) sensitively detects morphologic abnormalities due to chronic pancreatitis. However, morphologic EUS findings have limited specificity, particularly at the early stages of chronic pancreatitis. Our aims were to study pancreatic morphology and inflammation in patients with chronic pancreatitis, using EUS and fine-needle aspiration cytology (EUS-FNA), and to compare the results with those of endoscopic retrograde cholangiopancreatography (ERCP) and pancreatic function tests.

PATIENTS AND METHODS

37 patients (48 +/- 13 years) with clinical symptoms and laboratory test findings suggestive of chronic pancreatitis were prospectively studied. Patients with malignancy or major concomitant disorders were excluded. Clinical evaluation included indirect pancreatic function tests. Morphologic criteria for chronic pancreatitis included echo-intense septae/echo-reduced foci (i. e. pseudolobularity), ductal irregularities, and calcifications. EUS-FNA was performed in 27/37 patients, by means of the Hitachi FG34-UX echo endoscope and a 22-gauge needle, and tissue specimens were submitted for standard cytological evaluation. ERCP served as reference in all patients, using the Cambridge classification.

RESULTS

31 patients had chronic pancreatitis while six had normal findings at ERCP. EUS showed morphologic abnormalities of the pancreas in 33 patients. Morphologic abnormalities alone reached a sensitivity of 97 % for chronic pancreatitis with a specificity of only 60 %, while the positive predictive value (PPV) was 94 %, and the negative predictive value (NPV) was 75 %. EUS-FNA increased the negative predictive value to 100 % and the specificity to 67 %. On average, 2.3 needle passes were necessary to obtain sufficient amounts of tissue. The correlation of EUS findings with pancreatic function tests was poor. EUS results were in agreement with regard to the severity of chronic pancreatitis in 5/8 patients with grade I disease, in 11/13 patients with grade II, and in 10/10 patients with grade III disease. Minor complications occurred in two patients (7 %).

CONCLUSIONS

EUS is as sensitive and effective as ERCP in the detection of chronic pancreatitis, particularly when only mild disease is present. However, EUS findings have limited specificity, particularly in patients with mild disease. EUS-FNA with cytology is safe and improves the negative predictive value. Negative EUS-FNA findings rule out chronic pancreatitis, but cytological investigation alone does not improve the specificity of EUS findings, suggesting that further improvements in tissue sampling and analysis are necessary to support routine use of FNA in patients with chronic pancreatitis.

Enrichment of mutant KRAS alleles in pancreatic juice by subtractive iterative polymerase chain reaction

SUMMARY

The detection of mutant tumor genes holds great promise for an early diagnosis of primary tumors and residual malignant disease. When few tumor cells are present with an excess of nonmalignant cells of the same lineage, the excess of wild-type alleles over mutant tumor alleles presents an analytical problem. The subtractive iterative PCR (siPCR) assay presents a new approach to solving this problem. To achieve an enrichment of mutant alleles, wild-type alleles are removed by differential hybridization to complementary oligonucleotides spanning the region of the gene in which point mutations are expected. The nonbound fraction is reamplified by PCR. By iterating this process, mutant alleles can be detected in the presence of an excess of wild-type alleles with high sensitivity. To prove the feasibility of siPCR, pancreatic juice samples were analyzed for KRAS mutations. Pancreatic juice obtained from patients with pancreatic carcinoma or chronic pancreatitis during endoscopic retrograde cholangiopancreatography was analyzed for point mutations in codons 12 and 13 of the KRAS gene. In each of six samples from tumor patients, mutations in codon 12 were detected. One of nine samples from patients with chronic pancreatitis scored positive.

Brain electrical activity mapping of EEG for the diagnosis of (sub)clinical hepatic encephalopathy in chronic liver disease

We studied the role of brain electrical activity mapping (BEAM) in the assessment of neuropsychiatric disturbances in 48 cirrhotic patients without clinical evidence of hepatic encephalopathy (no HE, n = 19), with subclinical HE (grade 0, denoting pathological psychometric tests, n = 13) and mild-to-moderate HE (grade I, n = 6; grade II, n = 10). Results were compared with 23 healthy controls. BEAM variables quantified were: (i) the peak frequency (PF); (ii) the amplitude of PF; and (iii) the topographic localization of the maximum peak amplitude digitized for quantification by using a coordinate system. Mean amplitudes and their topographic localization in the following frequency-bands were analysed: delta (1.0-3.5 Hz), theta (4.0-7.5 Hz), alpha 1 (8.0-9.5 Hz), alpha 2 (10.0-11.5 Hz), beta 1 (12.0-15.5 Hz), beta 2 (16.0-19.5 Hz), and beta 3 (20.0-23.5 Hz). The PF was significantly slower in all HE patients than in healthy controls (8.5 +/- 2.0 Hz v. 10.1 +/- 1.0 Hz, P< 0.001). Even in no HE, the PF was significantly slower than in controls (8.6 +/- 1.5 Hz v. 10.1 +/- 1.0 Hz, P< 0.01). No relevant topographic differences of PF were observed. The mean amplitudes of the following bands differed significantly between controls and patients: theta (increased in HE, P< 0.05), alpha 2 (decreased in HE, P< 0.05), and beta 2 and beta 3 (increased in HE, (P < 0.05). In HE patients, the topographic localization of all beta bands showed a significant shift from parieto-occipital areas to central areas of the cortex. We conclude that BEAM is a sensitive tool for detecting neuropsychiatric disturbances in cirrhotics with no HE and with subclinical HE. The combination of PF in the theta band, increased mean amplitude in the beta 2 band, and the localization of the latter band in the frontocentral area of the cortex is an objective and sensitive tool for identifying neuropsychiatric disturbances in 85% of cirrhotic patients with no HE. Further studies are required to determine the clinical implications of these abnormal findings in the absence of overt clinical symptoms.

Objective assessment of cognitive factors involved in visceral perception by using event-related cerebral evoked responses to esophageal target stimulation in man

Evoked potential (EP) studies provide an objective measure of the neural pathways involved with perception of gastrointestinal stimulation. The effects of cognitive factors, such as anticipation or awareness, on EP responses are not known. We compared the EP response to esophageal electrical stimulation with the cortical activity associated with target detection and anticipation of the same stimulus. In 12 healthy men (26.8+/-6 years old), esophageal electrical stimulation (0.2 Hz, 0.2 msec, 15 mA) was applied, and the EP recorded using scalp electrodes. A computerized model of randomly applied target stimuli (1:5 ratio) was used to separately record the EP associated with stimulation and the event-related cognitive EP associated with a dual task-related or anticipated stimulation approach. A periodic electrical stimulus represented the nontarget stimulus and a second electrical impulse (oddball model) or an omitted stimulus (anticipatory model) the target stimulus. The event-related cognitive EP responses were also compared with standard and anticipatory auditory P300 evoked potentials. The esophageal and auditory oddball stimulus approach elicited event-related P300EP in all subjects. P300EP associated with electrical stimulation had a longer peak latency (P < 0.0001) and smaller amplitude than those obtained with auditory stimulation. Anticipatory evoked potentials could be obtained by electrical skipped stimulation in 8 of 12 subjects. These EP were similar to those obtained with omitted auditory target stimulation, although of significantly smaller amplitude than auditory standard P300EP (P < 0.001). In conclusion, the brain response associated with directed effortful processing of discriminate esophageal stimuli consists of a large event-related potential (P300EP). Anticipatory stimulation produces a similar event-related cortical response, which is associated with attention to and awareness of the actual stimulus. The P300EP to gastrointestinal stimuli may provide an objective and powerful electrophysiological tool for the assessment of the cognitive factors associated with visceral perception.

Effects of esophageal stimulation in healthy subjects

We studied the effects of esophageal electrical stimulation on heart rate variability power spectra (PS/HRV) and cortical evoked potentials (EPs) in healthy subjects. The intensity of stimulation was varied from 2.7 to 20 mA. We found that the amplitude of the cortical evoked potentials (amplitude of the N2/P2 peak) increased from 5.1 +/- 0.7 microV at 5 mA to 16.3 +/- 1.1 microV at 20 mA. The PS/HRV showed an increase in the vagal modulation of the sinus node. When the stimulation frequency was varied from 0.1 to 1 Hz at a constant intensity of 15 mA, the amplitude of cortical EPs (N2/P2 peak) decreased with increase in the frequency of stimulation (p < 0.05). The LF:HF ratio decreased significantly for all frequencies of stimulation (p < 0.005). An experimental paradigm to evoke the cognitive component in the cortical EPs yielded a peak around 354 ms following the stimulus.

Effects of esophageal stimulation in patients with functional disorders of the gastrointestinal tract

We studied the effects of esophageal electrical stimulation on cortical-evoked potentials (EPs) and power spectrum of heart rate variability (PS/HRV) in patients with diabetes and non-cardiac chest pain (NCCP). We also recorded cognitive-evoked potentials (P300 EPs) in response to an odd-ball stimulation in patients with NCCP. Diabetic patients did not yield reproducible cortical EPs. Their power spectra of heart rate variability (PS/HRV) showed an increased vagal modulation during stimulation. In patients with NCCP the P300 EPs were of greater amplitude (17 +/- 3 microV vs. 12 +/- 1 microV in controls, p < 0.04), while peak latencies were slightly elongated in patients (382 +/- 22 ms vs. 354 +/- 12 ms in controls). The PS/HRV in these patients also showed an increased vagal modulation of the sinus node activity. Our results suggest the following: (1) in patients with diabetes, afferent pathways and processing of sensory signals are likely to be impaired; (2) an increased perception of esophageal stimulation reflects an exaggerated brainstem response and altered cortical processing of visceral sensation in patients with NCCP.

[Ultrasonography of the inferior vena cava (IVC) in the diagnosis and monitoring of therapy in patients with chronic congestive heart failure]

OBJECTIVE

This prospective clinical study investigated whether the relatively simple and cost-effective ultrasonography of the inferior vena cava (IVC) represents a valid clinical tool to assess the effectiveness of diuretic therapy in patients with chronic congestive heart failure (CHF).

METHODS

Measurement of the resting and inspiratory diameter of the VCI repeatedly during diuretic therapy in 23 consecutive patients (11 women, 70 +/- 10 years) with CHF and comparing the results to the daily measured body weight and serum creatinine in these patients. Results were compared with the IVC diameter obtained in 33 healthy controls (16 women, 42 +/- 15 years). In addition, the IVC collapse index was calculated to assess inspiratory movements of the IVC in patients on day 1 and 10 of therapy.

RESULTS

The IVC diameter at rest was 2.4 +/- 0.6 cm and decreased to 2.0 +/- 0.7 cm at inspiration, which was significantly greater than in healthy controls (1.4 +/- 0.4 cm at rest and 1.05 +/- 0.5 cm at inspiration; p = 0.008 and p = 0.01, respectively). The IVC diameter decreased continuously and significantly (p < 0.003) from day 1 to day 10 during diuretic therapy without a concomitant rise in serum creatinine. At beginning of therapy, the collapse-index of the IVC was significantly greater in patients than in controls. However, after 10 days of therapy this index reached similar values to those observed in controls.

CONCLUSION

Ultrasonographic measurements of IVC diameter and inspiratory movements are a quantifiable and reliable approach to assess the hypervolemia associated with CHF. Normalization of inspiratory IVC collapse movement correlates with successful diuretic therapy and can be reliably used for bedside assessment and monitoring treatment in CHF patients.

Abnormal cerebral processing of oesophageal stimuli in patients with noncardiac chest pain (NCCP)

In noncardiac chest pain (NCCP), altered visceral perception may result from abnormal cerebral processing of sensory input rather than abnormalities of afferent pathways. However, the interactions between symptoms, autonomic function and oesophageal stimuli are poorly studied. Oesophageal stimulation elicits reproducible cortical evoked potentials [CEP] and modulates heart rate variability via vagal pathways, as visible on power spectrum analysis of heart rate variability [PS-HRV]. These methods are increasingly used to study the function of visceral afferent neural pathways in human. The aim of this study was to compare EP and PS-HRV during oesophageal stimuli in NCCP and controls. Twelve healthy volunteers (one female, 11 male; aged 24-51 years; mean 32 +/- 8 years), and eight NCCP patients (three female, five male; age range 26-58, mean 40.5 +/- 10 years) were studied. Electrical oesophageal stimulation (EOS; 200 microseconds, 0.2 Hz, 25 stimuli) was applied to the oesophageal wall 5 cm above the lower oesophageal sphincter (LOS), and perception thresholds (measured in mA) determined. EP responses were recorded using 22 standard electroencephalogram scalp electrodes. Autonomic activity was assessed using PS-HRV, before, during, and after oesophageal stimulation. Measured PS-HRV indices included high frequency (HF; 0. 15-0.5 Hz) and low frequency (LF; 0.06-0.15 Hz) power, respectively, assessing vagal and sympathetic activity, and the LF/HF ratio. EOS perception occurred at lower thresholds in NCCP than in controls (3. 6 +/- 1 vs. 7.8 +/- 2 mA, P < 0.05). EP amplitude was greater (13 +/- 2 vs. 6 +/- 1 microV, P < 0.0001), and latency longer in controls vs. NCCP (191 +/- 7 ms vs. 219 +/- 6 ms, P < 0.001). In NCCP, EOS decreased sympathetic outflow (low frequency peak on PS-HRV) and increased cardiovagal activity (high frequency peak, P < 0.02) to a significantly higher degree in comparison with controls. During EOS, heart rate decreased in NCCP from 68 vs. 62 beats min-1 (P < 0.003) but not in controls. In NCCP patients, EOS was perceived at lower intensities and was associated with a greater cardiovagal reflex response. EP responses associated with EOS were smaller in NCCP than in controls, suggesting that an increased perception of oesophageal stimuli results from an enhanced cerebral processing of visceral sensory input in NCCP, rather than from hyperalgesic responses in visceral afferent pathways.

[Pulmonary metastasis of extranodal high malignancy B-cell non-Hodgkin lymphoma of the bulbus duodeni and pylorus of the stomach]

We report a 71-year-old female patient with repeated vomitus, meteorism, epigastric pain and reflux for more than four month. She had a palpable mass in the upper abdomen and lost 7 kg of weight during the last four months. Chest X-ray showed two masses, 2 cm and 3 cm in diameter, in the left and right lower lung. A stenosing polypoid mucosal swelling in the antrum and the duodenal bulb. The pulmonal masses were biopsied under CT-guidance. Biopsy proved a high malignant B-cell non-Hodgkin's lymphoma of the stomach. The masses in the lung were identified as metastases of the gastrointestinal lymphoma. In conclusion on this tumor was an extranodal non-Hodgkin's lymphoma stadium BE IV according to Musshoff. A CHOP-chemotherapy was initiated. Restaging after three cycles of CHOP revealed a complete remission. Primary gastrointestinal non-Hodgkin's lymphomas are relatively rare neoplasms of the abdomen. Unusual and interesting in this case ist the metastatic pattern involving the lung periphery without local lymph node metastases.

Cognitive evoked potentials to anticipated oesophageal stimulus in humans: quantitative assessment of the cognitive aspects of visceral perception

Evoked potential studies provide an objective measure of the neural pathways involved with perception. The effects of cognitive factors, such as anticipation or awareness, on evoked potentials are not known. The aim was to compare the evoked potential response to oesophageal stimulation with the cortical activity associated with anticipation of the same stimulus. In 12 healthy men (23.5 +/- 4 years), oesophageal electrical stimulation (15 mA, 0.2 Hz, 0.2 msec) was applied, and the evoked potentials recorded using scalp electrodes. A computerized model of randomly skipped stimuli (4:1 ratio) was used to separately record the evoked potentials associated with stimulation and those associated with an anticipated stimulus. The electrical stimulus represented the nontarget stimulus and the skipped impulse the target (anticipatory) stimulus. This anticipatory evoked potential was also compared to auditory P300 evoked potentials. Reproducible evoked potentials and auditory P300 responses were elicited in all subjects. Anticipatory evoked potentials (peak latency 282.1 +/- 7.9 msec, amplitude 8.2 +/- 0.7 microV, P < 0.05 vs auditory P300 evoked potential) were obtained with the skipped stimulus. This anticipatory evoked potential was located frontocentrally, while the auditory P300 potential was located in the centro-parietal cortex. The anticipatory evoked potential associated with expectation of an oesophageal stimulus, although of similar latency to that of the auditory P300 evoked response, originates from a different cortical location. The recording of cognitive evoked potentials to an expected oesophageal stimulus depends on attention to, and awareness of, the actual stimulus. Anticipatory evoked potentials to GI stimuli may provide an objective electrophysiological tool for the assessment of the cognitive factors associated with visceral perception.

Neurocardiac and cerebral responses evoked by esophageal vago-afferent stimulation in humans: effect of varying intensities

OBJECTIVE

This study was designed to determine whether esophageal vago-afferent electrostimulation, over a wide range of stimulus intensities, can sustain a cardiac vago-efferent effect by way of central nervous system processing.

METHODS

Studies were performed in ten healthy male subjects (23.9 +/- 6.3 years). Esophageal electrostimulation was carried out using a stimulating electrode placed in the distal esophagus. Stimulation of esophageal vago-afferent fibres was employed using electrical impulses (200 microseconds at 0.2 Hz x 128 s) varying from 2.7 to 20 mA. Respiratory frequencies, beat-to-beat heart rate autospectra and cerebral evoked potentials were recorded at baseline and at each stimulus intensity in random order.

RESULTS

With esophageal electrical stimulation, we observed a small non-significant decrease in heart rate. There was a dramatic shift of the instantaneous heart rate power spectra towards enhanced cardiac vagal modulation with intensities as low as 5 mA. This effect was sustained throughout all intensities with no further change in either the low frequency or high frequency power. Conversely, there was a linear dose response relationship between cerebral evoked potential amplitude and stimulus intensity mainly occurring above perception threshold (10 mA). Esophageal stimulation had no significant effect on heart rate or respiratory frequency at any stimulus intensity.

CONCLUSIONS

These results indicate that electrical stimulation of the distal esophagus across a wide range of current intensities elicits a reproducible shift in the heart rate power spectrum towards enhanced vagal modulation. The data suggest a closed loop afferent/efferent circuitry wherein tonic visceral afferent impulses appear to elicit a phasic or modulatory vago-efferent cardiac response in healthy subjects.

Cortical evoked responses following esophageal balloon distension and electrical stimulation in healthy volunteers

Recording of evoked potential responses represents an objective and quantifiable method to study visceral afferent sensory pathways in humans. We examined the evoked responses to mechanical distension (balloon) and electrical stimulation of the proximal and distal esophagus. A standard manometric catheter with a latex balloon and an additional electrode attached to its body was placed in the lower esophagus in 15 healthy young volunteers. Repeated nonpainful balloon distension stimuli above the individual sensation threshold (0.17 Hz, 12-20 ml) or short electrical impulses (0.2 Hz, 12-16 mA) were delivered in an alternate fashion at 23 and 33 cm from the nares. Evoked potential responses (EP) were recorded through 22 scalp surface electrodes using the standard 10/20 International EEG system of electrode placement. Balloon distension produced a reproducible triphasic response at both sites. Peak latencies of three negative EP peaks were 92+/-17, 229+/-40, and 339+/-36 msec with proximal stimulation versus 154+/-24, 275+/-24, and 384+/-30 msec obtained with distal stimulation (P < 0.001). Electrical stimulation produced a triphasic response with significantly shorter peak latencies at both sites when compared to mechanical stimulation (P < 0.001). Peak latencies were 74+/-12, 137+/-11, and 245+/-27 msec proximal versus 83+/-12, 148+/-32, and 247+/-51 msec with distal stimulation (P < 0.01). The calculated conduction velocities for both modes of stimulation (balloon: 1.73+/-0.9 m/sec vs electrical: 10.1+/-3.4 m/sec) are compatible with conduction through C fibers and Adelta fibers, respectively. Both modes of stimulation produce characteristic brain responses that are conveyed through different types of afferent fibers. The respective contributions of both types of fibers to esophageal function and symptomatology can be specifically addressed using this approach in both normal and pathologic conditions.

The accuracy of abdominal ultrasound in the assessment of bowel disorders

BACKGROUND

Little is known about the sensitivity, specificity, and predictive values of transabdominal ultrasonographic (US) findings in a teaching hospital setting.

METHODS

We carried out a prospective study including 227 patients with symptoms suggestive of inflammatory bowel disorder. The Picker 9200 CS equipment (5-mHz curved-array probe) was used to obtain bowel images. Gastrointestinal endoscopy, enteroclysis, bowel enema, computed tomography scan, or bowel surgery was used as reference.

RESULTS

Of 227 patients, 168 had pathologic findings of the bowel as final diagnosis. The overall sensitivity of US was 76%, whereas the positive predictive value was 98%. Overall specificity was 95%. The negative predictive value for bowel disorders was only 58%, since US missed pathologic findings in 48 patients. Subgroup analysis showed a sensitivity of 84% for Crohn's disease, 66% for ulcerative colitis, 46% for bowel tumors, and 60% for diverticulitis. Topographic comparisons showed that US detected inflammatory bowel-wall alterations preferentially in the terminal ileum and colon, whereas abnormalities in the duodenum, jejunum, and rectum were frequently missed (sensitivity, 10%-20%).

CONCLUSIONS

Positive US findings are useful for the diagnosis of bowel processes. US is highly predictive albeit not disease-specific. Negative US examinations, however, do not exclude pathologic bowel processes. A topographic location of pathologic US findings is mostly confined to the colon.

Assessment of afferent gut--brain function using cerebral evoked responses to esophageal stimulation

Increasing awareness is attributed to altered sensory perception in the pathogenesis of gastrointestinal disorders. Evoked potentials (EP), which represent the brain's electrical response to peripheral stimulation, have recently been used to investigate where and how (GI) afferent information is processed along the brain-gut axis. EP can be obtained with electrical stimulation or balloon distention in the esophagus in humans. Stimulation of afferent neural pathways in the esophagus produces cerebral evoked responses allowing assessment of the peripheral afferent neural pathways involved, and of the function of integrative neural centers within the brain. Recent studies using esophageal EP indicate that the cerebral response to either mode of stimulation depends on the perception of the stimuli. Using electrical stimulation, a clear dose-response relationship is found. The EP response obtained with electrical stimulation is in keeping with those recorded using direct cervical stimulation of the vagus nerve, supporting evidence that esophageal EP are produced by activation of afferent vagal pathways. From the conduction velocity of the autonomic (vagal) nerves conveying information from esophagus to brain, it was concluded that non-painful electrical stimuli predominantly activate fast conducting myelinated afferent sensory fibers (A-fibers), while EP to balloon distention are largely due to activation of unmyelinated C-fibers. Techniques, however, vary widely amongst different investigators, and some electrophysiological parameters remain controversial, as there is no standard approach. Using balloon distention, EP waveforms vary widely between laboratories, suggesting that EP are substantially influenced by the stimulator devices (pump, respirator). EP to balloon distention are hampered by a relatively low signal-to-noise ratio (SNR), which is probably due to long inflation-deflation time (> 200 ms). With electrical stimulation, there is much less variability between different groups, and SNR is distinctly higher. This method appears to be most attractive for studies of afferent esophageal function. Standardization of the techniques is important, before esophageal EP can be regarded as a useful diagnostic approach in patient groups.