Bilateral middle cerebellar peduncle lesions

Last revised by Rohit Sharma on 4 Feb 2024

Bilateral lesions of the middle cerebellar peduncles, resulting in the middle cerebellar peduncle sign, are uncommon and can be seen either in isolation (rare) or along with other regions of involvement.

Despite their relative rarity, they have a fairly long list of potential causes (see below) 1-4. Among these neurodegenerative diseases are probably most common.

The middle cerebellar peduncles are composed of white matter that connects the cerebellar hemispheres to the contralateral pontine nuclei 5. Therefore, many of the causes of lesions in this location are related to white matter pathology.

They are supplied by branches of the anterior inferior cerebellar artery and the superior cerebellar artery.

For additional discussion of region anatomy refer to middle cerebellar peduncles.

Although potentially visible on CT, in most instances this is an MRI feature.

The majority of patients presenting with bilateral middle cerebellar peduncle lesions have high T2 signal without suppression on FLAIR, with matching low signal on T1 weighted images 4. This will usually have facilitated diffusion on ADC maps.

Diffusion restriction (low ADC values) may be seen acutely in infarction and in lymphoma 4. Enhancement is usually absent although some enhancement may be seen in lymphoma 4.

Most of the entities listed do not usually cause isolated bilateral middle cerebellar peduncular lesions and as such care must be taken in identifying other areas of involvement.

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