18F-FDG PET/CT: an unexpected case of Huntington's disease.

Background: Huntington's disease (HD) is a rare, genetic neurodegenerative disorder often presenting with emotional, cognitive and behavioral abnormalities before manifestation of disease defining motor symptoms. Cognitive impairment is a frequent clinical feature caused by different dementia subtypes. Imaging cortical and subcortical glucose metabolism via F-FDG PET/CT can help to discriminate the underlying disease.

Case Presentation: The patient is a 54-year old man presenting with progressive cognitive impairment and mild orofacial dyskinesia. F-FDG PET/CT of the brain revealed a severe bilateral hypometabolism in the striatum. Following imaging Huntington's disease was suspected and a molecular genetic testing confirmed the diagnosis.

Conclusions: Huntington's disease is a rare but important differential diagnosis of cognitive impairment, especially before motor symptoms are manifest. F-FDG PET is capable to show early striatal dysfunction in HD even when structural imaging is normal. We conclude that, in cases with negative family history the HD characteristic metabolic pattern can lead to the diagnosis when no other dementia-suspected changes are present.