Search for a rare disease

* (*) mandatory field

Other search option(s)

Suggest an update

(*) Required fields.


Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Orphanet doesn't provide personalised answers. To get in touch with the Orphanet team, please contact

Information provided in your contribution (including your email address) will be stocked in .CSV files that will be sent as an email to Orphanet's teams. These emails might be conserved in the teams' mailboxes, in our backoffice servers but will not be registered in our databases (for more information see our section General Data Protection Regulation and data privacy (GDPR) and Confidentiality).

Captcha image

Mega-cisterna magna

Disease definition

A rare, non-syndromic, posterior fossa malformation characterized by a cisterna magna that measures above 15 mm in length, 5 mm in height and 20 mm in width (or greater than 10 mm in fetuses) associated with a normal cerebellar vermis and absence of hydrocephalus. The majority of patients are asymptomatic; however, variable neurodevelopmental outcomes, including delayed speech and language development, motor development delay, visiospatial perception difficulties, and attention problems, has been observed in some patients.


Classification level: Disorder
  • Synonym(s): -
  • Prevalence: -
  • Inheritance: -
  • Age of onset: -
  • ICD-10: Q07.8
  • OMIM: -
  • UMLS: C3164501
  • MeSH: -
  • GARD: -
  • MedDRA: -
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.