RESUMEN
BACKGROUND: Patients with essential tremor (ET) are at higher risk to develop Parkinson's disease (PD). Recent studies suggest that propranolol (common treatment for ET) can augment pathologic expression of alpha-synuclein. We studied features associated with the development of Parkinson's disease with antecedant essential tremor (ET-PD) compared with ET-plus with parkinsonism (PK). DESIGN: Retrospective case series from a tertiary movement disorders center including patients with ET and PD, found to have ET-PD or ET-plus (PK). RESULTS: We analyzed two groups: (1) ET-plus (PK) (n = 33) and (2) ET-PD (n = 35). Constipation and anosmia were more common in the ET-PD group (73% and 48%) than in the ET-plus (PK) group (33% and 19%). The ET-plus (PK) group was more likely to undergo dopamine transporter (DAT) scans compared with the ET-PD group (73% vs. 34%) and less likely to receive levodopa trials (21% vs. 91%). There were no significant differences in self-reported REM sleep behavior disorders or beta-blocker use. Similar rates of depression, anxiety, cognitive complaints, and family history of tremor or PD were reported in both groups. CONCLUSION: ET-PD and ET-plus (PK) can be clinically difficult to differentiate as they have overlapping motor and non-motor features. Beta-blocker use did not predict development of ET-PD or ET-plus (PK); however, anosmia and constipation may be helpful non-motor distinguishing features. DAT scans and levodopa trials may be valuable in clarifying the diagnoses.