EOPD patients require close monitoring for disease progression since they are at a higher risk for treatment related complications. SN hyperechogenicity, an established biomarker to differentiate PD from other forms of parkinsonism, has been shown to remain stable with an area >0.2cm² in advanced PD patients (≥H&Y stage II). 

36 EOPD patients in Stage I as determined by the Unified Parkinson’s Disease Rating Scale (UPDRS) in the “off” state, performed by a rater blinded to the TCS, consented into this prospective study. All UPDRS were videotaped and verified by an independent rater. TCS was performed by a blinded sonographer and  measurements of SN hyperechogenicity >0.2 cm² were classified as significant on each side.

At V1, hyperechogenicity that met >0.2cm² was found exclusively on the contralateral SN of 32 subjects. Mean contralateral and ipsilateral SN hyperechogenicity was 0.270 ± 0.062 cm² and 0.144 ± 0.057 cm² respectively. At a mean of 408 days after V1, 72.7% of the patients (N=22) displayed hyperechogenicity >0.2cm²ipsilaterally. We previously reported bilateral SN hyperechogenicity by day 750 from V01 in all subjects, whereas only 8 of the 21 subjects had clinically progressed to stage II. Further follow up showed that ipsilateral SN hyperechogenicity gradually increased >0.2cm² prior to developing stage II disease on UPDRS  testing in the “practically defined off state” in all subjects performed by the rater blinded to the TCS.