Changes in glucose metabolism in essential tremor: within and beyond the cerebello-thalamo-cortical circuit

The pathophysiology and cerebellar role in essential tremor are not yet fully understood. Previous fludeoxyglucose positron emission tomography (FDG-PET) studies comparing glucose metabolism between essential tremor and healthy participants have led to few and inconsistent results. We aimed to examine changes in brain glucose metabolism in [¹⁸F]FDG PET brain imaging in 19 right-handed essential tremor patients and compare them to 19 right-handed healthy participants using a voxel-based mass univariate analysis. The Montreal Cognitive Assessment and the Hospital Depression scale were used as covariates. In addition, the correlation between tremor severity as measured with the Fahn-Tolosa-Marin Tremor Rating Scale and brain glucose metabolism in essential tremor patients was assessed. Essential tremor patients showed significantly higher metabolism in the right dentate nucleus and, at a more liberal threshold, lower metabolism in the right parietal cortex. A positive correlation was detected between glucose metabolism in the left paracentral region and tremor severity, again at more liberal thresholding. Beyond the cerebello-thalamo-cortical circuit, the decreased activity in the right parietal areas in essential tremor patients may indicate that the sensorimotor integration is an important aspect of essential tremor pathophysiology. In conclusion, our findings show altered glucose metabolism within and beyond the cerebello-thalamo-cortical circuit.