Studies in A-scan echoencephalography: evaluation of a proposed two phase shift

A series of 440 patients studied by echoencephalography is reported. Rather than dividing the patients in the classic two groups of less than 3 mm and more than 3 mm deviation of the midline, the patients in this study were divided into three groups, correlating the degree of midline shift to the presence of intracranial pathology. Group I, showing 0 to 2.5 mm shift proves to be normal with a "miss" rate of only 10%. Group II, showing 2.5 to 3.5 mm shift is regarded as a borderline group with an incidence of significant intracranial pathology of 46%, clearly indicating the need for further evaluation. Group III, demonstrating greater than 3.5 mm shift from the midline, is designated with confidence as abnormal, with a yield of significant intracranial pathology of 100% in this study