A<unk>  is a<unk>  collection of cerebrospinal fluid (CSF), without blood. The<unk>  space is a virtual one, so any collection within it is considered as abnormal. Most<unk> s are believed to be derived from chronic<unk>  hematomas. It is commonly seen in elderly after minor trauma but can be seen in children after an infection. One of the common causes of<unk>  is sudden decrease in pressure by ventricular shunting. This can lead to leak of CSF into the<unk>  space especially in cases with moderate to severe brain atrophy. In these cases the symptoms such as mild fever, headache, drowsiness and confusion can be seen, which are relieved by draining this<unk>  fluid.
Subdural hygroma
Arachnoid cyst
Encephalocele
Craniopharyngioma
Schizencephaly
Choroid plexus papilloma
Hydrocephalus
Megalencephaly