Cerebellar agenesis

What it means

Cerebellar agenesis is defined by the near complete absence of cerebellar tissue with only remnants of the anterior vermis, flocculus, and/or middle cerebellar peduncles.

Usually, small remnants of the cerebellum are present; therefore the term subtotal cerebellar agenesis is also used in the literature. A secondary pontine hypoplasia is typically seen. The definition of cerebellar agenesis is based on the morphologic pattern and does not suggest the pathogenesis. Cerebellar agenesis may represent a malformation (e.g., mutations in PTF1A) or a disruption (e.g., hemorrhage that occurs during gestation or in the perinatal period, vascular insufficiency in Chiari II malformation and cerebellar herniation, and as a sequela of prematurity).

Rare diseases that can present with this1

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