Mega Cisterna Magna

Excerpt

The cisterna magna is a cerebrospinal fluid (CSF) filled space located in the posterior fossa dorsal to the medulla and caudal to the cerebellum. Mega cisterna magna refers to a cystic posterior fossa malformation characterized by an enlarged cisterna magna, absence of hydrocephalus, and an intact cerebellar vermis.

The concept of mega cisterna magna was first introduced in the 1960s by Gonsette; its size was initially described on ventriculography as above 15 mm in anterior-posterior length, 5 mm height, and 20 mm width. The size has more recently been proposed as a cisterna magna that is greater than 10 mm on mid-sagittal images.