Lateral wall of the olfactory fossa in determining intracranial extension of sinus carcinomas

The role of plain skull radiography and pluridirectional tomography in determining anterior cranial fossa extension of paranasal sinus tumors is reassessed. The lateral wall of the olfactory fossa, a thin bony plate forming part of the roof of the ethmoid sinuses, is routinely visualized on plain skull radiography and pluridirectional tomography in the coronal plane and serves as an indicator of intracranial tumor extension. In a series of 47 patients with paranasal sinus tumors, 100% true positive and 3% false negative interpretations of the integrity of the lateral wall of the olfactory fossa were made with pluridirectional tomography. Interpretations with plain skull radiography were 90% true positive and 3% false negative. Assessment of the integrity of the lateral wall of the olfactory fossa by these techniques provides an accurate evaluation of the presence of intracranial tumor extension by this route. Computed tomography in the coronal plane with contrast infusion is a useful adjunct.