<unk> s are seen in up to 1.1% of the population with a gender distribution of 2:1 male:female. Only 20% of these have symptoms, usually from secondary hydrocephalus. A study that looked at 2,536 healthy young males found a prevalence of 1.7% (95% CI 1.2 to 2.3%). Only a small percentage of the detected abnormalities require urgent medical attention.
Arachnoid cyst
Subdural hygroma
Labyrinthine fistula
Frontal horn cyst
Cystic hygroma
Choroid plexus papilloma
Choroidal fissure cyst
Hemicrania continua