Clinical, electrophysiological, and imaging study in essential tremor-Parkinson's disease syndrome

• DOI: 10.1016/j.parkreldis.2018.06.005
• Publication Date: 2018-06-05T07:56:16Z
• Authors: Gennarina Arabia; Angela Lupo; Lucia Ilaria Manf...; Basilio Vescio; Rita Nisticò; Gaetano Barbagallo; Maria Salsone; Maurizio Morelli; Fabiana Novellino; Giuseppe Nicoletti; Andrea Quattrone; Giuseppe Lucio Ca...; Elan D. Louis; Aldo Quattrone
• Keywords: Male; Tomography, Emission-Computed, Single-Photon; Blinking; Reflex, Abnormal; Electromyography; Essential Tremor; Parkinson Disease; -; Middle Aged; 3. Good health; Cohort Studies; Diagnosis, Differential; 03 medical and health sciences; 0302 clinical medicine; Humans; Female; Aged

Essential tremor-Parkinson's disease (ET-PD) syndrome is a clinical condition in which individuals with a long-lasting history of Essential tremor (ET) eventually develop Parkinson's disease (PD). The aim of the study was to investigate the accuracy performances of clinical, neurophysiological, and imaging biomarkers in differentiating patients affected by ET-PD syndrome from patients with ET or PD.Nineteen patients affected by ET-PD syndrome, 48 ET patients, and 37 tremor-dominant PD (t-PD) patients were included. Electrophysiological studies, including blink-reflex recovery cycle and tremor parameters analyses, were performed in all groups. Nigro-striatal and cardiac sympathetic denervation were also investigated. Sensitivity, specificity and accuracy of clinical, electrophysiological, and radiological features in differentiating ET-PD syndrome from ET and PD were calculated.ET-PD patients had significantly lower rigidity (p = 0.007) and higher postural/kinetic tremor (p = 0.007) scores, in comparison to t-PD patients. ET-PD patients, differently from PD patients, had a synchronous pattern of resting tremor and, differently from ET patients, had abnormal blink-reflex recovery cycle. ET-PD patients also showed reduced nigro-striatal and cardiac sympathetic uptakes, albeit to a lesser extent than in PD patients. The highest accuracy values were found for the synchronous pattern of resting tremor (97.1%) in distinguishing ET-PD from PD, and for presence of abnormal blink-recovery cycle (100%) in distinguishing ET-PD syndrome from ET.Our study demonstrates that some electrophysiological parameters, such as a synchronous resting tremor pattern and the abnormal blink-recovery cycle were the most accurate biomarkers in distinguishing patient with ET-PD syndrome from those with ET or those with PD.