Effects of Alprazolam on Cortical Activity and Tremors in Patients with Essential Tremor.
Author: Ibáñez, Jaime; González de la Aleja, Jesús; Gallego, Juan A.; Romero Muñoz, Juan Pablo; Saíz Díaz, Rosana A.; Benito León, Julián; Rocón, Eduardo
Abstract: Background: Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4–12 Hz. Previous
studies suggest that the tremor activity originates in the cerebello-thalamocortical pathways. Alprazolam is a short-acting
benzodiazepine that attenuates tremors in ET. The mechanisms that mediate the therapeutic action of alprazolam are
unknown; however, in healthy subjects, benzodiazepines increase cortical beta activity. In this study, we investigated the
effect of alprazolam both on beta and tremor-related cortical activity and on alterations in tremor presentation in ET
patients. Therefore, we characterised the dynamics of tremor and cortical activity in ET patients after alprazolam intake.
Methods: We recorded hand tremors and contralateral cortical activity in four recordings before and after a single dose of
alprazolam. We then computed the changes in tremors, cortico-muscular coherence, and cortical activity at the tremor
frequency and in the beta band.
Results: Alprazolam significantly attenuated tremors (EMG: 76.2622.68%), decreased cortical activity in the tremor
frequency range and increased cortical beta activity in all patients (P,0.05). At the same time, the cortico-muscular
coherence at the tremor frequency became non-significant (P,0.05). We also found a significant correlation (r = 0.757, P,
0.001) between the reduction in tremor severity and the increased ratio of cortical activity in the beta band to the activity
observed in the tremor frequency range.
Conclusions: This study provides the first quantitative analysis of tremor reduction following alprazolam intake. We
observed that the tremor severity decreased in association with an increased ratio of beta to tremor-related cortical activity.
We hypothesise that the increase in cortical beta activity may act as a blocking mechanism and may dampen the
pathological oscillatory activity, which in turn attenuates the observed tremor.
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