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

Abstract

To date, 3 mm shift of the midline intracranial structures has been considered normal. In our experience much significant pathology is found in individuals demonstrating midline shifts within the border zones of 3 mm. Establishment of an intermediary zone of midline shift around 3 mm between normal and abnormal seemed desirable and would be significant in alerting the physician to seek pathology by additional available means of diagnosis. The purpose of this study is to present data in support of this hypothesis.We will not concern ourselves with the type and precise location of the neoplastic and other pathology encountered. Such discussions have been presented by several previous workers. MATERIAL AND METHODSEchoencephalography was performed on 440 consecutive cases. An Ekoline 20 Diagnostic Ultrasonoscope was used. This was equipped with a Polaroid LandCamera for permanent recording. The transducer probe was a barium titanate crystal with a diameter of 17.5 mm operating at 2.25 megacycles with approxi mately 200 pulses per second and a pulse length of 1 microsecond. The recordings were performed by placing the transducer at the squamous portions of the temporal From the