Specific Imaging Findings

The characteristic imaging finding of Huntington disease (HD) is bilateral striatal (caudate nucleus and putamen) atrophy, particularly involving the heads of the caudate nuclei. This leads to symmetric enlargement of the adjacent frontal horns with flattening of their lateral contour. Signal abnormalities are not typically seen in adults. In the juvenile form of the disease, T2 hyperintensity may be observed in the caudate nucleus and putamen. Diffuse cerebral atrophy with white matter volume loss, generally more pronounced in the frontal lobes, is evident late in the course of the disease. Decreases in tissue volume are accompanied by increasing ADC values within the caudate nucleus, putamen, and periventricular white matter.

Pertinent Clinical Information

HD (also known as Huntington's chorea) is a neurodegenerative disorder characterized by the triad of fully penetrant dominant inheritance, progressive movement disorder, and dementia. Onset of symptoms is typically in the mid-30s to mid-40s, but it may occur as early as the first (juvenile form) and as late as the tenth decade of life. Chorea with brief, abrupt involuntary movements is prototypical for HD, with a much broader spectrum of possible motor signs. As the disease progresses, chorea is superseded by dystonia or akineto-rigid parkinsonian features. The disease is relentlessly progressive, resulting in death within 10-20 years after symptom onset, or less with the juvenile form. The diagnosis is made on the basis of characteristic motor signs and a positive family history, confirmed by genetic testing.