Rare diseases · Sign or symptom
Enlarged cisterna magna
HP:0002280
What it means
Increase in size of the cisterna magna, one of three principal openings in the subarachnoid space between the arachnoid and pia mater, located between the cerebellum and the dorsal surface of the medulla oblongata.
Cerebrospinal fluid produced in the fourth ventricle drains into the cisterna magna via the lateral apertures and median aperture.
Rare diseases that can present with this18
Sometimes5–29%
11- Atelosteogenesis type I
- Autosomal dominant spastic paraplegia type 9A
- Autosomal recessive cerebelloparenchymal disorder type 3
- Joubert syndrome with Jeune asphyxiating thoracic dystrophy
- Microcephaly-corpus callosum and cerebellar vermis hypoplasia-facial dysmorphism-intellectual disability syndrome
- Mosaic trisomy 1 syndrome
- PMM2-CDG
- Proximal 16p11.2 microdeletion syndrome
and 3 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Large cisterna magna · Mega cisterna magna
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.