Mega cisterna magna

Case contributed by Dr Abdel-Rahman Abdel-Halim

Presentation

Headache

Patient Data

Age: 14
Gender: Male
Modality: CT

Prominent cisterna magna appearing as a wedge shaped area of CSF density in the midline posterior fossa region resting on the inner table of the squamas portion of the occipital bones. Its apex is seen pointing at the cerebellar vermis. A fold of the arachnoid membrane is seen crossing inside the cistern.

Case Discussion

A mega-cisterna magna, is a controversial subject. In general however, the term refers to non-pathological enlargement of the retro-cerebellar CSF space and not associated with cerebellar abnormalities (normal cerebellar vermis and hemispheres).

Differential diagnosis include Dandy Walker malformations and variants, Cerebellar hypoplasia, posterior fossa arachnoid cyst, epidermoid cysts.

One of the supportive findings for the diagnosis of mega cistern magna is the presence of internal lines crossing inside the cistern representing folds of the arachnoid membrane. These folds virtually  are not seen in any similar lesion like retrocerebellar arachnoid cyst and dandy – walker malformation.    

PlayAdd to Share

Case Information

rID: 31489
Case created: 13th Oct 2014
Last edited: 8th Feb 2016
Inclusion in quiz mode: Included

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.