Macrocerebellum, also known as cerebellar hyperplasia, refers to a rare condition characterized by an abnormally enlarged cerebellum with preserved architecture and shape. It is usually demonstrated on imaging with a thickening of the cortical grey matter of the cerebellar hemispheres.
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Epidemiology
Macrocerebellum is a rare imaging finding, only a few case have been reported 3.
Clinical presentation
It is usually dependent on the underlying disease. Hypotonia, ataxia, and ocular movement disorders are related in patients with an isolated macrocerebellum 1,2.
Pathology
The etiology is unknown. For some authors, it is not considered as an independent entity, but a manifestation of different conditions 2,3. For others, it is a cerebellar response to the elaboration of growth factors intended to augment the slow development of cerebral structures 1.
It can be found as an isolated (non-syndromic) condition or as part of a well-defined syndrome, such as Costello syndrome and Sotos syndrome, or neurometabolic diseases (e.g. mucopolysaccharidosis type I and II) 2.
Radiographic features
There is no malformation, only a diffusely enlarged cerebellum, especially due to cerebellar hemispheres cortical grey matter 2,3.