Transcranial color-coded sonography helps differentiation between idiopathic Parkinson's disease and vascular parkinsonism

Background Recently, transcranial color-coded sonography (TCCS) has been found to have a diagnostic value in patients with idiopathic Parkinson's disease (IPD), which displays increased hyperechogenicity at the substantia nigra (SN). Objective To use TCCS, to assess the difference in SN hyperechogenicity and intracranial hemodynamics among subjects with IPD, vascular parkinsonism (VP) and controls. Methods Eighty IPD and 30 VP patients, and 60 controls were recruited into this study. The hyperechogenicity area at the SN and midbrain were calculated by encircling the outer circumference from the ipsilateral temporal window, using TCCS in each subject. The hemodynamics of intracranial large arteries, including flow velocity and pulsatility index (PI), were also measured. Results The presence of SN hyperechogenicity was significantly higher in the IPD patients than in the VP patients and controls (84% vs. 20% & 5%, respectively, p < 0.001). In IPD patients, the SN hyperechogenicity was correlated with the neurological severity and disease duration. Twenty-five (66.7%) VP patients had obvious vascular abnormality, as seen in TCCS study. The mean PI was significantly more elevated in the VP patients than those in the IPD patients and controls (all p < 0.05), but there was no significant difference of flow velocities among the VP, IPD patients and controls. Conclusions TCCS, combining B-mode imaging for SN echogenicity and trancranial Doppler for intracranial hemodynamics, is a useful diagnostic tool in the differentiation between IPD and VP. These findings also suggest that multiple subcortical vascular lesions may damage the basal ganglia and thalamocortical circuit and result in parkinsonism features in VP patients.