Transcranial sonography in Huntington's disease.

Transcranial sonography (TCS) has become a reliable and sensitive diagnostic tool in the evaluation of extrapyramidal movement disorders, especially in the differentiation of Parkinsonian syndromes. Although only rarely reported, TCS reveals also signal alterations of basal ganglia in Huntington's disease (HD). Distinct findings are related to all of the three symptom domains of the clinical triad of the disease. The TCS finding of substantia nigra hyperechogenicity was related to higher clinical disease severity. A poorer cognitive performance correlated with larger width of third ventricle. Moreover, widths of frontal horns of lateral ventricles measured with TCS corresponded closely to diameters estimated by CT imaging. Depressive symptoms were found to be associated with abnormal echogenicity of mesencephalic raphe structures. Furthermore, a larger number of CAG repeats in the huntingtin gene correlated with presence of SN hyperechogenicity. This review provides information about the examination procedure and its diagnostic value in HD. Possible morphological and pathophysiological mechanisms leading to changes in the reflection of ultrasound waves are discussed in the context of established neuroimaging modalities.