Effect of L-DOPA on re-emergent tremor in Parkinson?s disease: a neurophysiological assessment

MIGUEL WILKEN; ALEX MEDINA ESCOBAR; MALCO ROSSI; MARCELO MERELLO

Berlin

Congreso; 20th International Congress of Parkinson?s Disease and Movement Disorders; 2016

BackgroundSome patients with Parkinson?s disease can present postural and action tremor in addition to rest tremor. Previous studies have shown that when patients with rest tremor change position, they commonly have a silent period (SP) without tremor, before its re-emergence. The modification of the re-emergence of Parkinsonian tremor during an acute L-DOPA challenge test has not been previously established. ObjectivesTo conduct a neurophysiological analysis on the postural re-emergence of tremor in PD patients during an acute L-DOPA challenge test. Material and MethodsAn accelerometer-based tremor study was conducted on 6 PD patients with clinically defined re-emergent tremor. The study was performed during an acute L-DOPA challenge test, in order to analyze tremor characteristics in both ON and OFF situations, and to correlate its modifications with the response to the drug. Tremor amplitude and duration of the SP were analyzed in the OFF state (baseline), and every 15 minutes until maximum response to L-DOPA (MDS-UPDRS part III) was achieved. Every test was repeated 5 times with and without distraction to ensure consistency. ResultsWe observed no time gap between the acquisition of a fixed posture from the resting position and the start of tremor activity displayed by the accelerometer, even when it was not clinically evident. However, tremor amplitude increased, becoming clinically visible after a variable period of time (range 0-22.5 sec within the five repetitions in each state). Spectral analysis showed that frequency remained unchanged (5.3±1.0 Hz) with amplitude increment. With distracting maneuvers, the mentioned augmentation comes faster, making tremor clinically evident earlier (0.0 sec vs 6.6±7.2 sec, p