27         SA JOURNAL OF RADIOLOGY • June 2006

Several conditions may present with a small cerebellum on MRI. These 

can be classified into 3 categories.1

An atrophic cerebellum is a small cerebellum with enlarged fissures. 

A cerebellum is also considered to be atrophic if it has been shown to 

have undergone progressive loss of volume (Fig. 1).1 This can occur with 

children in the hereditary condition of Friedrich’s or spinocerebellar 

ataxia.

A hypoplastic cerebellum has folia which are in proportion to the 

fissures: a uniformly small perfectly proportioned structure (Fig. 2). 

Examples of cerebellar hypoplasia include pontocerebellar hypoplasia 

and Wolfram syndrome.1 

Lastly, a hypogenetic cerebellum has a formed superior portion, but 

an absent inferior portion (Figs 3 and 4). In the Dandy Walker complex 

a focal insult to the developing cerebellum causes variable hypoplasia 

of the postero-inferior portion of the cerebellar vermis and dysgenesis 

The small cerebellum in children – a useful 
approach on MRI

PICTORIAL INTERLUDE

S Richards, MB ChB  
S Adronikou, MB BCh,  

FCR Diag (SA), FRCR (Lond), PhD

Department of Paediatric Radiology, Tygerberg Hospital and University of 
Stellenbosch

Fig. 1. Cerebellar atrophy. Sagittal T1 image shows deepened cerebellar 
fissures relative to folial size.

Fig. 3. Cerebellar hypogenesis. Sagittal T1 image shows almost complete 
absence of the vermis and an enlarged posterior fossa with associated 
hydrocephalus.

Fig. 2. Cerebellar hypoplasia. Sagittal T1 image shows the folia and fis-
sures to be in proportion in a small cerebellum.  

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CASE REPORT

28         SA JOURNAL OF RADIOLOGY • June 2006

of the hemispheres. There is communication between the 4th ventricle 

and cisterna magna, and cystic dilatation of the 4th ventricle in the true 

Dandy Walker syndrome.2 The Dandy Walker complex is a spectrum of 

posterior fossa cystic anomalies.1

1.    Barkovich JA. Paediatric Neuroimaging, 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2000: 143-

145, 339-341.

2.    Dahnert W. Radiology Review Manual, 5th ed. Philadelphia: Lippincott, Williams & Wilkins, 2003: 274. 

Fig. 4. Cerebellar hypogenesis. Sagittal T1 image with cerebellum 
demonstrating dysgenesis with a formed superior and absent inferior 
portion.

CASE REPORT

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