BACKGROUND AND PURPOSE:Essential tremor (ET) and Parkinson's disease (PD) sometimes overlap in their clinical expression with ET preceding PD onset, often leading to misdiagnosis. Transcranial sonography (TCS) has been shown to be a valid and non-invasive diagnostic tool to identify early idiopathic PD and to differentiate it from ET. The purpose of this study was to investigate the relevance of substantia nigra hyperechogenicity in patients with ET.METHODS:A total of 138 patients (79 with PD, 59 with ET) and 50 matched controls underwent TCS examination at baseline. All patients were followed in a 3-year longitudinal assessment.RESULTS:A total of 10 subjects were excluded from the analysis due to the bilateral absence of a temporal acoustic window. During the follow-up period, 11 of the patients with ET developed new-onset parkinsonian features, without fulfilling criteria for PD diagnosis (ET+). Nine patients developed clinical features meeting diagnostic criteria for probable PD (ET-PD). Patients with ET- did not develop parkinsonian features. For each group, the maximum size of the substantia nigra hyperechogenicity was as follows: 5.62 ± 5.40 mm2 in the control group, 19.02 ± 14.27 mm2 in patients with PD, 9.15 ± 11.26 mm2 in patients with ET-, 20.05 ± 13.78 mm2 in patients with ET+ and 20.13 ± 13.51 mm2 in patients with ET-PD. ET-PD maximum values were significantly different from controls. Maximum values in patients with ET+ were different from both controls and patients with ET-.CONCLUSION:Substantia nigra hyperechogenicity in ET seems to represent a risk marker for developing early parkinsonian symptoms or signs in the 3 years following TCS assessment.

Introduction Brain iron load is an important neuropathological mark in Parkinson’s disease (PD) and it can be quantified by MR susceptibility-weighted imaging (SWI). We estimated the correlation between cerebral iron distribution evaluated by SWI and cognitive pattern in a group of PD patients. Materials and methods 32 patients and 10 healthy subjects comparable for age and gender were enrolled. Patients were examined for motor and cognitive assessment. Cognitive outline was assessed with MoCA for global cognitive abilities and with a battery of neuropsychological tests. Functional daily abilities were tested using ADL and IADL scales. Patients and controls underwent MRI acquisition on a 3.0 T Philips Achieva system. For each emisphere seven ROIs were considered: putamen, globus pallidus, caudate nucleus, red nucleus, substantia nigra, dentate nucleus and frontal white matter. We measured SWI-intensity values for each ROI: lower values correspond to higher iron content. All the collected data were expressed as mean value and standard deviation. Chi-square test was used to verify associations between categorical variables. Results Higher iron deposits were detected in all the ROIs in patients compared to controls. SWI-intensity values of substantia nigra correlates negatively with disease duration and UPDRS-III off and positively with ADL and IADL scores. A positive and significant relationship between MoCA (<26 cut-off) and SWI-intensity values in putamen, globus pallidus and substantia nigra was found. WAIS-IV Similarities shows a significant positive association with SWI-intensity values in all the ROIs, moreover Spatial Span and Gradient Named Test positively correlate with SWI intensity values of substantia nigra. Conclusions According to literature [ [1] Zhang J, Zhang Y, Wang J, et al. Characterizing iron deposition in Parkinson’s disease using susceptibility-weighted imaging: an in vivo MR study. Brain Res 2010;1330:124–30. Google Scholar ], brain iron distribution estimated by SWI seems to be a useful tool for cognitive decline in PD.