Increased size of the head since birth. Head circumference measuring 49.4 cm (more than 99 percentile for age) representing macrocephaly. Currently presented for pre-shunt assessment.
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- vermis hypoplasia with superior rotation of the vermian remnant associated with large posterior fossa cyst elevating the tentorium and straight sinus communicating with the fourth ventricle.
- marked dilatation of supra-tentorial ventricular system with free communication between the third and fourth ventricle and no aqueduct stenosis identified
- hypoplastic cerebellum with a winged appearance
- thinned occipital bone
- thinned stretched and elevated corpus callosum
- widened supraoptic, infundibular and pineal recesses of the third ventricle
- flow void is noted at the cerebral aqueduct denoting patency
- wide foramina of Monro, foramen of Luschka and Magendie.
- no significant signal alteration of the white matter, no transependymal SCF permeation
In an infant presenting with progressive macrocephaly, hydrocephalus is suspected. Brain MRI shows features of arrested marked hydrocephalus involving supra-tentorial ventricular systems and normal cortical sulci. Flow void is noted at the aqueduct denoting patency.
A large cystic area occupies the posterior fossa communicating directly with the fourth ventricle. Normal vermis cannot be identified, with a small vermian remnant appearing displaced and rotated superiorly. Features are consistent with a Dandy Walker malformation with associated marked arrested hydrocephalus, mostly communicating type. Patients usually present with macrocephaly in the first year of life.
Dandy-Walker malformation classical triad consists of:
- hypoplasia of the vermis and cephalad rotation of the vermian remnant
- cystic dilatation of the fourth ventricle extending posteriorly
- enlarged posterior fossa with torcular-lambdoid inversion (the torcula lying above the level of the lambdoid due to abnormally high tentorium)