Is it common for there to be obstructive hydrocephalus at presentation?
About three-quarters have obstructive hydrocephalus, presenting in the early part of the first year of life. More than half of patients will have associated neurological abnormalities.
What are the differentials for cystic posterior fossa abnormalities?
Mega cisterna magna, epidermoid cyst, arachnoid cyst are amongst the differentials.
Posterior fossa cystic abnormality communicating with the 4th ventricle with gross hydrocephalus.