cystic malformation of the posterior fossa Blake pouch cyst https://www.malacards.org/card/blake_pouch_cyst UMLS:C3662124 MONDO:0020351 GARD:0019603 Blake pouch cyst is a non-syndromic, usually benign, cystic malformation of the posterior fossa characterized by a midline outpouching of the superior medullary velum into the cisterna magna that results from failure of the rudimental fourth ventricular tela choroidea to regress during embryogenesis. Patients can be asymptomatic or present in childhood or adulthood with clinical manifestations of hydrocephalus, such as headache, hypotonia, vertigo, syncope, vomiting, blurred or double vision, nystagmus, papilledema, and delayed gait development. MEDGEN:783279 Orphanet:98922