Objective Response to Ethanol in Essential Tremor: Results from a Standardized Ethanol Challenge Study

OBJECTIVE:To investigate the objective response to ethanol in patients with Essential Tremor (ET) using a standardized ethanol-challenge and digital spiral-analysis as objective outcome measure.BACKGROUND:Beneficial response of tremor to even small amounts of ethanol is considered a characteristic feature of ET. Data on ethanol-response however rely on subjective data, with benefit in up to 74[percnt] of patients. This implies that ethanol-response - or lack thereof - in ET represents an endophenotypic feature. To investigate the mechanism of ethanol-response in ET, the goal of this study was to describe the objective responder-rate to a standardized ethanol-dose, and investigate predictors for response.DESIGN/METHODS:85 subjects with ET were included in a prospective, open-label, single-dose challenge of oral ethanol in a dose aimed to reach a blood alcohol content (BAC) of 0.05g/dl. Digital spirals and BAC were collected at baseline and in 20min intervals for 2 hours after administration. Positive response was operationally defined as u003e35[percnt] reduction of spirographic tremor at 60min after administration.RESULTS:68/85 (80[percnt]) patients were responders, and 17 (20[percnt]) were non-responders. There was no difference of gender or race between the groups. Subjective responder status, as assessed by history prior to the challenge, did not predict objective response. After including all other time-points as criterion for response, 81 subjects (95[percnt]) were considered responders. While there were no differences in mean BAC levels between responders and non-responders, there was a significant inverse correlation of spiral tremor score at 60min and peak-BAC (r=-0.24, p=0.03).CONCLUSIONS:Our study demonstrates that the historical information on subjective ethanol-response is not predictive of an actual objective response. Furthermore, the response profiles to ethanol did not allow a clear distinction between responders and non-responders, but rather suggested a continuous response, with BAC as potential predictor of response.Study Supported by: NINDS Intramural Research Program. Disclosure: Dr. Haubenberger has nothing to disclose. Dr. Auh has nothing to disclose. Dr. Thompson-Westra has nothing to disclose. Dr. Buchwald has nothing to disclose. Dr. McCrossin has nothing to disclose. Dr. Voller has nothing to disclose. Dr. Ramchandani has nothing to disclose. Dr. Hallett has nothing to disclose.