Gamma-encephalography in the diagnosis of subdural effusions in infancy and childhood.

The results of the use of gamma-encephalography (GEG) as a diagnostic tool in a group of 28 patients with subdural effusions and 46 membranes confirmed at surgery are presented. 27 patients were submitted to bilateral surgical expolorations and 1 was unilaterally explored. Positive GEG: membranes were present in 34, in 8 the test was nonconclusive and there were 4 false-negatives. Negative GEG: membranes were absent in 6, 1 case was nonconclusive and 2 were false-positive tests. Therefore, from 28 patients with 46 membranes the GEG was correct in two thirds of the cases, it was nonconclusive in 9 cases and the image did not confirm the surgical findings in 6 cases (false-positive or false-negative). The results suggest that the presence of a medium or thick membrane almost always results in a positive image, whereas the presence of a thin membrane leads to a nonconclusive result or in some cases a false-negative one. The general data from the literature correlates well with the present series.