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Substantia nigra (SN) hyperechogenicity on brain parenchyma sonography (BPS) is highly characteristic for idiopathic PD. We studied 7 symptomatic and 7 asymptomatic parkin mutation carriers (PMC) from a large kindred with adult-onset parkinsonism. BPS revealed larger SN echogenic sizes in PMC with parkin mutations on both alleles (homozygous, compound-heterozygous), compared to PMC with only one mutated allele (Mann-Whitney U test, P = 0.007). In symptomatic PMC, larger SN echogenic size was correlated with younger age at onset of the disease (Spearman rank correlation, Rho = -0.937, P = 0.002) but not with age, disease duration, or disease severity. BPS demonstrated SN hyperechogenicity, in concordance with abnormal nigrostriatal (18)F-dopa positron emission tomography (PET), in all symptomatic and 3 asymptomatic PMC. In 2 asymptomatic PMC, PET and BPS were normal. However, in another 2 asymptomatic PET-normal PMC, SN hyperechogenicity could be detected. Data suggest SN hyperechogenicity as an early marker to detect preclinical parkinsonism.
Walter et al. (Wed,) studied this question.