Medicine Section - Cutaneous Electrogastrography (EGG)

IMPORTANT REMINDER

Regence Medical Policies are developed to provide guidance for members and providers regarding coverage in accordance with contract terms. Benefit determinations are based in all cases on the applicable contract language. To the extent there may be any conflict between the Medical Policy and contract language, the contract language takes precedence.

PLEASE NOTE: Contracts exclude from coverage, among other things, services or procedures that are considered investigational or cosmetic. Providers may bill members for services or procedures that are considered investigational or cosmetic. Providers are encouraged to inform members before rendering such services that the members are likely to be financially responsible for the cost of these services.

Description

Electrogastrography describes the recording and interpretation of electrical activity of the stomach. Recordings can be made from the gastrointestinal mucosa, serosa, or skin surface. Because of its ease of use, cutaneous EGG has been used most frequently and is the focus of this policy.

The electrical activity of the stomach can be subdivided into two general categories: electrical control activity (ECA) and electrical response activity (ERA). ECA is characterized by regularly recurring electrical potentials, originating in the gastric pacemaker located in the corpus of the stomach and sweeping in an annular band with increasing velocity toward the pylorus. ECA is not associated with contractions of the stomach unless coupled with action potentials, referred to as ERA. The usual practice is to record several cutaneous EGG signals from various standardized positions of the abdominal wall and to select the one with the highest amplitude for further analysis. Nonetheless, the recorded signal is relatively weak and difficult to distinguish from the surrounding background "noise" related to unwanted signals, such as cardiac, respiratory, duodenal, and colonic electrical activity. For this reason, direct visual analysis of the EGG is problematic. Various methods of filtering out background noise and automated analysis have been developed; running spectral analysis is most common. The EGG is usually evaluated in terms of changes in the EGG amplitude and frequency. Deviations from the normal frequency of 3 cycles per minute may be referred to as brady- or tachyarrhythmia.

The use of EGG has been most widely studied in patients with gastroparesis and functional dyspepsia. Gastroparesis is defined as a chronic disorder of gastric motility as evidenced by delayed gastric emptying of a solid meal. Symptoms include bloating, distension, nausea, and vomiting. When severe and chronic, gastroparesis can be associated with dehydration, poor nutritional status, and poor glycemic control in diabetics. While most commonly associated with diabetes, gastroparesis is also found in chronic pseudo-obstruction, connective tissue disorders, Parkinson disease, and psychological pathology. Functional dyspepsia is an enigmatic disorder characterized by persistent symptoms of abdominal discomfort with no identifiable etiology, including gastric emptying. In this setting, disorders in gastric motility may be considered. Treatment of gastric motility disorders typically include the use of prokinetic agents, such as cisapride, domperidone, or metoclopramide.

Scintigraphic gastric emptying is considered the gold standard test for evaluating gastroparesis. The test consists of ingestion of a solid meal with the addition of 99-technetium. Serial scintigraphic measurements are then performed every 20 minutes for 2-3 hours after the meal. Delayed gastric emptying is diagnosed if more than 50% of the radiolabeled food is retained at the end of the study period. While scintigraphic gastric emptying evaluates the efficiency of gastric emptying, EGG focuses on the underlying myoelectrical activity.

Policy/Criteria

Electrogastrography is considered investigational.

Scientific Background

Validation of the clinical use of any diagnostic test focuses on three main principles:

1. The technical feasibility of the test
2. Basic statistical measurements, such as sensitivity, specificity, and positive and negative predictive values in different populations of patients and compared to the gold standard
3. How the results of the diagnostic test will be used in the management of the patient and whether or not the change in treatment will result in an overall improvement in health outcomes

Based on a review of the published peer reviewed literature, there are inadequate data to evaluate any of the above principles.

Technical Feasibility

Electrogastrography (EGG) recording faces several technical challenges, many of them related to measuring cutaneous signals, rather than directly measuring electrical activity along the stomach mucosa or serosa. One of the parameters of the EGG analyzed is the power of the signal, commonly thought to increase after the digestion of a meal. However, the power of the signal can also be influenced by the proximity of the electrode to the stomach wall, which can change as the stomach distends after a meal. (2,3) Changes in frequency, such as tachyarrhythmias and bradyarrhythmias, are commonly reported. However, EGG artifacts, such as movement artifacts and signal drift, may limit interpretation. Simultaneous recordings of cutaneous and internal EGGs suggest that cutaneous EGG records more episodes of tachyarrhythmias, probably due to the accumulation of artifacts. The use of computer-assisted analysis, which may not be able to identify and eliminate movement artifacts, must be interpreted very cautiously. Day to day variability of the EGG is another important issue, as measured by repeated EGG in the same patient over a short period of time.

Diagnostic Performance

Several studies have compared EGG with gastric emptying tests and have reported a poor correlation between the two. (4-8) Two of the larger studies are reviewed here. Chen and colleagues performed both EGG and scintigraphic emptying in 97 patients with symptoms suggestive of gastroparesis. (8) Considering gastric emptying tests as the gold standard, the authors concluded that patients with delayed gastric emptying had either a lower percentage of normal slow waves, or a higher prevalence of gastric dysrhythmias, or both. However the sensitivities of these three parameters were 24%, 42%, or 14%, respectively, while the corresponding specificities were 92%, 87%, and 100%. The authors concluded that an abnormal EGG may predict delayed gastric emptying, however a normal EGG will not rule out delayed gastric emptying. One hypothesis is that normal gastric myoelectrical activity is one of many prerequisites for normal gastric emptying.

Parkman and colleagues correlated abnormalities in EGG with gastric emptying and symptom severity in 72 patients with functional dyspepsia. (7) Patients were recruited from those who were referred for a gastric emptying scintigraphy. A total of 22 patients (31%) had an abnormal EGG and 22 (31%) had an abnormal gastric emptying test. The EGG was abnormal in 11 of the 22 patients (50%) with an abnormal gastric emptying test. If the gastric emptying scintigraphy is considered the gold standard, the EGG had a sensitivity of 50% and a specificity of 78%. While these data suggest that EGG cannot be substituted for gastric emptying scintigraphy, it must be noted that the two tests are measuring different aspects of gastric activity. Therefore, another question is the clinical significance of those with abnormal EGGs but negative emptying tests and whether the two tests are complementary. Patients with abnormalities in both tests tended to report increased symptom severity, but the authors did not comment on the diagnostic significance of this observation.

One study did focus on how EGG could be used as an adjunct to gastric emptying studies, by focusing on the subset of patients with known delayed gastric emptying and no dysrhythmias observed on the EGG. (9) The authors concluded that while the patients with idiopathic gastroparesis were likely to have gastric dysrhythmias, patients with mechanical obstruction were more likely to have persistent and prominent 3 cycles per minute EGG patterns, which are seen in normal EGGs. This observation suggests that patients with known gastroparesis based on gastric emptying studies may be further evaluated with an EGG. If no dysrhythmias are found, the patients may be referred for further tests to identify subtle mechanical obstructions. If EGG dysrhythmias are found, the patients might benefit from a trial of a prokinetic agent. However, this study was retrospective in nature, and the results must be confirmed in larger prospective studies.

Other studies have focused on the use of EGG in diabetic patients as a research tool to study the pathogenesis of diabetic gastroparesis. Kawagishi and colleagues studied the relationship between glucose control, autonomic neuropathy, and EGG findings. They concluded that improved glycemic control and improved autonomic nerve function were associated with normalization of gastric myoelectrical activity. (10) Mantides and colleagues reported that abnormalities in the EGG are frequently detected in diabetes even without symptoms of gastroparesis. (11)

Patient Management

No study focused on the final patient outcomes in patients undergoing EGGs. Outcomes of interest could include the avoidance of unnecessary tests or unnecessary treatment, or the institution of potentially more effective treatment. Based on the studies reviewed above, due to the low sensitivity of EGG for diagnosis of gastric motility disorders compared to scintigraphic gastric emptying studies, it is unlikely that EGG can supplant tests of gastric emptying. As an adjunct to gastric emptying tests, one study suggested that EGG could be used to distinguish patients with mechanical obstruction from idiopathic gastroparesis. (9) However, this one study did not include patient outcomes.

In summary, while EGG may be an interesting research tool to study the correlation between gastric electrical activity and disease, there are inadequate data to determine how the results of this test may be used to benefit patient management.

Subsequent reviews of the published literature since the policy originated suggests that EGG is primarily used as a research tool in patients with a variety of disorders. (12-15) Other studies continue to focus on the technical performance of the test. (16, 17) No study was identified that elucidated the diagnostic performance of EGG in different populations of patients or how this information could be used to benefit patient management. In 2001, the American Gastroenterological Association published a medical position statement on nausea and vomiting (18), which offered the following conclusion:

"Although well-documented disorders of enteric nerve and muscle such as the pseudo-obstruction syndrome may result in nausea and vomiting, the role of gastrointestinal dysmotility and gastroparesis, in particular, in the patient with isolated chronic nausea and vomiting remains unclear. Although gastroparesis is common among patients in this category, its primacy remains in dispute, and the interrelationships between such entities as functional and psychogenic vomiting, idiopathic gastroparesis, and functional dyspepsia remain unclear. For these same reasons, the place of such tests of motor function as gastric emptying studies, electrogastrography, and manometry have not been defined, and the yield of such diagnostic studies has not been adequately compared with a therapeutic trial of an antiemetic and/or prokinetic agents."

Annual updated literature searches performed on the MEDLINE database in March 2006 and 2007 did not identify published literature that addresses the limitations noted in the above discussion.  All new published literature continues to focus on technical performance of EGG.  However, no new studies address the diagnostic performance of EGG or how EGG data are used to benefit patient management. (19-22)

EGG continues to be a frequently used research tool for assessing the level of gastric function and mechanisms of dysfunction for a variety of disease states. Some recent papers assessed the reliability of EGG. One study assessed the utility of EGG to differentiate between patients with reflux disease (n=101), active gastric ulcer (n=55), and functional dyspepsia (n=59). (23) Following water loading, abnormal EGG results were obtained in 41% of patients with reflux disease, 56% of patients with active gastric ulcer, and 44% of patients with functional dyspepsia. The absence of significant differences in the percentages of abnormal results indicates that EGG cannot differentiate between these various gastric diseases. Another study assessed short-term (one day) and medium-term (greater than two weeks) reproducibility of EGG parameters in 22 healthy volunteers following ingestion of identical meals. (24) Analysis with the Cohen unweighted kappa statistic indicated moderate to good reproducibility for parameters assessing the frequency of gastric slow waves. However, parameters describing the power of gastric slow waves had only fair reproducibility. The authors concluded that the feasibility of some electrogastrographic parameters to convey clinically useful information may be hampered by the limited reproducibility of results.

A position statement on the diagnosis and treatment of gastroparesis from the American Gastroenterological Association in 2004 reported that the guideline developers discussed, but did not recommend, the use of EGG to test for gastric myoelectrical activity. (25) Overall, the literature indicates that the use of EGG is investigational.

An updated search of the MEDLINE database through June 2009 did not identify any evidence that would alter the conclusions reached above.  Two recent studies concluded that the reproducibility and clinical utility of EGG are poor. (26,27)  This technology has not been shown to improve the net health outcome; the policy statement is unchanged.

References

1. BlueCross and BlueShield Association Medical Policy Reference Manual, Policy No. 2.01.34
2. Verhagen MAMT, Van Schelven LJ, Samsom M, Smout AJPM. Pitfalls in the analysis of electrogastrographic recording. Gastroenterology 1999;117:453-60
3. Bortolotti M. Electrogastrography: A seductive promise only partially kept. Am J Gastro 1998;93:1791-94
4. Koch KL, Medina M, Bingaman S, Sterm RM. Gastric dysrhythmia and visceral sensations in patients with functional dyspepsia. Gastroenterol 1992;102:A469
5. Koch KL, Sterm RM, Stewart WR, Vasey MW. Gastric emptying and gastric myoelectrical activity in patients with diabetic gastroparesis; effect of long term domperidone treatment. Am J Gastroenterol 1989;84:1069-75
6. Smout AJPM, Jebbink HJ, Akkermans LMA, Bruijs PPM. Role of electrogastrography and gastric impedance measurements in evaluating gastric emptying and motility. Dig Dis Sci 1994;39:110S-3S
7. Parkman HP, Miller MA, Trate D et al. Electrogastrography and gastric emptying scintigraphy are complementary for assessment of dyspepsia. J Clin Gastroenterol 1997;24:214-19
8. Chen JDZ, Lin Z, Pan J, McCallum RW. Abnormal gastric myoelectrical activity and delayed gastric emptying in patients with symptoms suggestive of gastroparesis. Dig Dis Sci 1996;41:1538-45
9. Brzana RJ, Koch KL, Bingaman S. Gastric myoelectrical activity in patients with gastric outlet obstruction and idiopathic gastroparesis. Am J Gastroenterol 1998;93:1803-09
10. Kawagishi T, Nishizawa Y, Emoto M et al. Gastric myoelectrical activity in patients with diabetes: Role of glucose control and autonomic nerve function. Diabetes Care 1997;20:848-53
11. Mantides A, Stefanides G, Kioulanis J et al. Cutaneous electrogastrography for the assessment of gastric myoelectrical activity in Type 1 diabetes mellitus. Am J Gastroenterol 1997;92:1190-93
12. Aktay AN, Splaingard ML, Miller T et al. Electrogastrography in children with cystic fibrosis. Dig Dis Sci 2002;47(4):699-703
13. Levy J, Harris J, Chen J et al. Electrogastrographic norms in children: toward the development of standard methods, reproducible results, and reliable normative data. J Pediatr Gastroenterol Nutr 2001;33(4):455-61
14. Koch KL. Electrogastrography: physiological basis and clinical applications in diabetic gastropathy. Diabetes Technol Ther 2001;3(1):51-62
15. Mathur R, Pimentel M, Sam CL et al. Postprandial improvement of gastric dysrhythmias in patients with type II diabetes: identification of responders and nonresponders. Dig Dis Sci 2001:46(4):705-12
16. Koch KL, Hong SP, Xu L. Reproducibility of gastric myoelectrical activity and the water load test in patients with dysmotility-like dyspepsia symptoms and in control subjects. J Clin Gastroenterol 2000;31(2):125-9
17. Lin A, Eaker EY, Sarosiek I et al. Gastric myoelectrical activity and gastric emptying in patients with functional dyspepsia. Am J Gastroenterol 1999;94(9):2384-9
18. American Gastroenterological Association medical position statement: nausea and vomiting. Gastroenterology 2001;120(1):261-3
19. Simonian HP, Panganamamula K, Chen JZ et al. Multichannel electrogastrography (EGG) in symptomatic patients: a single center study. Am J Gastroenterol 2004;99:478-85
20. Chen CL, Lin HH, Chen SY, Lin SZ. Utility of electrogastrography in differentiating Parkinson’s disease with or without gastrointestinal symptoms: A prospective controlled study.  Digestion 2005;71:187-191
21. Lu CL, Chen CY, Luo JC et al. Impaired gastric myoelectricity in patients with chronic pancreatitis: Role of maldigestion.  World J Gastroenterol 2005;11(3):372-376
22. Bentur L, Hino B, Shamir R et al. Impaired gastric myoelectrical activity in patients with cystic fibrosis. J Cystic Fibrosis 2006;5:187-91
23. Chen CL, Hu CT, Lin HH et al. Clinical utility of electrogastrography and the water load test in patients with upper gastrointestinal symptoms. J Smooth Muscle Res. 2006; 42(5):149-57
24. Jonderko K, Kasicka-Jonderko A, Krusiec-Swidergol B et al. How reproducible is cutaneous electrogastrography? An in-depth evidence-based study. Neurogastroenterol Motil. 2005; 17(6):800-9
25. Parkman HP, Hasler WL, Fisher RS. American Gastroenterological Association medical position statement; diagnosis and treatment of gastroparesis. Gastroenterology 2004;127(5):1589-91
26. Abid S, Lindberg G.  Electrogastrography: poor correlation with antro-duodenal manometry and doubtful clinical usefulness in adults.  World J Gastroenterol 2007;13(38);5101-7
27. Krusiec-Swidergol B, Jonderko K.  Multichannel electrogastrography under a magnifying glass- an in-depth study on reproducibility of fed state electrogastrograms. 2008 Neurogastroenterol Motil 2008;20(6):625-34

Cross References

None

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