CT Findings of Compressive Lesions at the Optic Canal

Abstract

Due to the topographical peculiarities around the optic canal, which are described in Chap. 2, even very small mass lesions or moderate changes of local structures may cause optic nerve compression and eventually blindness. In the past, such small lesions often could not be visualized by conventional radiographic methods, including polytomography and angiography. The introduction of thin section CT has considerably improved the evaluation of small mass lesions, hyperpneumatization of the sphenoid bone, and alterations of the local soft tissue structures, particularly the internal carotid arteries. CT has remained the method of choice for radiological evaluation of this region. It must be recognized, however, that to visualize or rule out small lesions in particular, specific techniques of examination as well as a thorough knowledge of the normal anatomy and its physiological variations are necessary to avoid false negative results or overinterpretations.