Effect of skull rotation on x-ray evidence of displaced midline structures

Abstract

✓ During the initial urgent management of patients with acute brain lesions, skull roentgenograms or cerebral angiograms often result in rotated views. The classical method of maximum transverse measurement for the diagnosis of lateral displacement of the opacified pineal gland or great vein of Galen retains its validity in eight of 10 anteroposterior cranial roentgenograms rotated 8° and in nine of 10 rotated 5°. The explanation is expressed by the “circle in the skull” hypothesis which indicates that those portions of the lateral cranial wall whose projections serve as referential points for the maximum transverse measurement, form arcs of a circle of which the radius is the pineoparietal distance. The concept of the midsagittal arch of the skull is introduced as a method of cranial midline determination on rotated anteroposterior skull roentogenograms. This method gives dependable indication of significant shift of the opacified pineal gland and deep cerebral veins according to the criteria described.