EGG, similar to an electorcardiogram (EKG) of the heart, records the electrical signals that travel through the muscles of the stomach controlling the muscles’ contractions. Additionally, EGG measures stomach wall nerve activity before and after food ingestion. EGG has existed in the past, but was cumbersome, recording only one electrical channel at a time. Therefore there was little capability for muscle activity comparison and in order to record electrical signals in various parts of the stomach needed to be repeated numerous times. The new EGG system records on four channels simultaneously allowing for complete activity recording in a short time frame.
How is EGG done?
EGG is a non-invasive test, relatively inexpensive, and easy to perform. Electrodes are placed cutaniously on the abdominal skin over the stomach. While the patient is lying down relaxing, the electrodes record the electrical activity of the stomach. Initially, the gastric electrical activity is recorded after fasting, then again after a small meal is ingested. Sometimes EGG is done in conjunction with or after gastric emptying studies to diagnose and manage functional dyspepsia and idiopathic gastroparesis. The EGG test lasts approximately one hour.
Why does a patient need EGG?
EGG is an appropriate diagnostic tool when there is a suspicion that the nerves controlling stomach muscles or the stomach muscles themselves are not working normally. EGG can be used for a variety of gastrointestinal motility disorders or for patients with no known GI disorder who are suffering from unexplained nausea. EGG frequently identifies dysrhythmias, especially after meals, in patients with gastroparesis, chronic dyspepsia, anorexia nervosa and bulimia, cyclic vomiting syndrome, and other conditions characterized by a delayed gastric emptying.
Gastric myoelectric activity is composed of mainly two complementary rhythms; slow wave activity, responsible for muscle contraction timing, and electrical response activity, responsible for triggering peristaltic contractions. EGG measures too much activity, tachygastria, too little activity, bradygastria, or mixed dysfunction of both too much and too little activity.
How are the results evaluated?
Utilizing computer analysis, the power of the stomach muscle electrical current is measured. In a normal stomach muscle, the regular electrical rhythm generates an increased current after a meal. In persons with stomach muscle or nerve irregularities, the post-meal electrical rhythm is irregular or voltage does not increase.