THE FORAMEN MAGNUM - THE UNDERUTILIZED ACOUSTIC WINDOW TO THE POSTERIOR-FOSSA

Visualization of the posterior fossa during neonatal cranial sonograph y through the anterior fontanelle can at times be limited. To improve visualization of the posterior fossa, the foramen magnum was used as a n acoustic window. Scans through the foramen magnum were obtained in a ddition to routine scans via the anterior fontanelle in 21 preterm inf ants. A subjective and retrospective evaluation was performed comparin g clarity and definition of posterior fossa structures using the anter ior fontanelle and foramen magnum. Images of the fourth ventricle, pon s, vermis, cerebellar hemispheres, and cisterna magna were considered superior in clarity and definition when obtained via the foramen magnu m. The tentorium was visualized equally well with both windows. Forame n magnum scanning demonstrated improved clarity of two Dandy-Walker va riants in comparison to anterior fontanelle scanning. The use of the f oramen magnum in addition to other acoustic windows can improve percei ved clarity and definition of posterior fossa structures and aid in th e detection of abnormalities and anomalies occurring in this location.