Imaging Through the Posterior Fontanelle

Abstract

Sonography of the posterior fontanelle is easily performed and yields exquisite details of the outline of the major structures of the posterior fossa and the tentorium. These structures are more clearly outlined through the posterior fontanelle than via the traditional anterior fontanelle approach, probably because the longitudinal axis of the sonographic beam passing through the posterior fontanelle is nearly perpendicular to the outline of the aqueduct of Sylvius, the fourth ventricle, the brain stem, the cerebellar vermis, and the tentorium. Several cases are presented briefly to illustrate the sonographic appearance of the normal and abnormal infratentorial anatomy via a posterior fontanelle approach. (J Child Neurol 1989;4:S62-S67).