The middle cerebellar peduncle (MCP) sign is a feature of a number of conditions, particularly neurodegenerative diseases, and most commonly associated with fragile X-associated tremor/ataxia syndrome (FXTAS) although many other conditions are recognised.
It represents high T2 signal in the middle cerebellar peduncles, which contain the frontocerebellar tracts (connecting to orbitofrontal and dorsolateral prefrontal cortex) 1.
The MCP sign is seen in a number of conditions including 1,2:
- chronic liver disease
- Behcet disease
- chasing the dragon (heroin inhalation toxic leukoencephalopathy)
- cyclosporin-A encephalopathy
- HIV encephalopathy
- recessive ataxia
- spinocerebellar ataxia
- multiple system atrophy - cerebellar (MSA-C): atrophy is usually the striking abnormality
- fragile X-associated tremor/ataxia syndrome (FXTAS)
- bilateral anterior inferior cerebellar artery infarction
- posterior reversible encephalopathy syndrome (PRES)
- Wallerian degeneration secondary to pontine stroke
It can of course also be encountered 'randomly' in diseases that have no particular regional predilection (e.g. stroke, tumour).
- 1. Kalus S, King J, Lui E et-al. Fragile X-associated tremor/ataxia syndrome: An under-recognised cause of tremor and ataxia. J Clin Neurosci. 2016;23: 162-4. doi:10.1016/j.jocn.2015.08.010 - Pubmed citation
- 2. Okamoto K, Tokiguchi S, Furusawa T et-al. MR features of diseases involving bilateral middle cerebellar peduncles. AJNR Am J Neuroradiol. 2003;24 (10): 1946-54. AJNR Am J Neuroradiol (full text) - Pubmed citation