Neuroradiology of basal anterior fossa (transethmoidal) encephaloceles.

Encephaloceles of the basal anterior fossa, though primarily congenital in origin, may be insidious in presentation and remain undetected until adulthood. Conventional plain films and hypocycloidal tomograms show a basal osseous defect with its margins bevelled toward the nasopharynx. Magnification angiography is the diagnostic study of choice and reveals herniation of the anterior inferior frontal artery through the osseous defect. Pneumoencephalography, the classical technique of investigation, was found to be unrewarding in demonstrating the herniated sac or in determining the presence or absence of brain tissue within the sac; however, it is of value in demonstrating a ventricular communication with the encephalocele and evaluating ventricular dilatation.