[The spectral component of electrogastrography (EGG): factors of variation in normal subjects, and in patients with cancer and ulcers].

A study of the spectral analysis of the electrogastrography has been mad in man in a non-invasive condition: normal subjects in two groups: young and old subjects (n = 72) were compared with gastric cancers (n = 42) and ulcerous (n = 22) subjects. Morning recording (10-11 h a.m.), in fasting conditions, were repeated every three successive days. In normal subjects, the mean frequency of the spectral gastric component is very stable (2.8 +/- 0.2 cycles per min), whatever be the sex, the age of the body weight. In normal subjects, the mean spectral amplitude (y) varied with the derivation: in derivation 3-6 (according to the antro-pyloric axis) is the greatest amplitude (y = 52 +/- 22 microV). In the cancerous condition, the range of the frequencies increases, but the mean frequency does not change (2.8 +/- 0.3 cycles per min). However, in 7 cancerous subjects the frequencies (x) fell beyond the limits of the population with an (x) being either less than or equal to 2.4 or greater than or equal to 3.2 cycles per min. In a great proportion (forty-seven per cent) of the cancerous subjects, an important and significant increase of amplitude is recorded (at least in one derivation). In these cases, the location of the cancer is the cardia, the fundus or the pylorus. The amplitudes fall significantly beyond those observed in ulcerous patients. The possible explanations of these variations and the applications to the future monitoring of patients are discussed.