Bilateral cerebellar activation in unilaterally challenged essential tremor

Area of Science:

• Neuroscience
• Movement Disorders
• Neuroimaging

Background:

• Essential tremor (ET) is a common hyperkinetic movement disorder.
• Previous research suggests cerebellar abnormalities underlie ET pathophysiology.

Purpose of the Study:

• To investigate the localization of bilateral cerebellar abnormalities in Essential Tremor using simultaneous electromyography-functional MRI (EMG-fMRI).
• To enhance the precision of identifying tremor-related brain activations in a homogeneous group of ET patients.

Main Methods:

• Included 21 propranolol-sensitive ET patients and 21 healthy controls.
• Performed simultaneous EMG-fMRI recordings during unilateral right hand and arm extension (inducing tremor) and rest.
• Analyzed fMRI data using EMG power variability at individual tremor frequency as a regressor to identify tremor-specific activations.

Main Results:

• Both ET patients and controls showed block-related activations in the upper-limb motor network.
• ET patients exhibited tremor-related activations bilaterally in the cerebellum (lobules V, VI, VIIb, IX on left; V, VI, VIIIa, b on right) and brainstem.
• Healthy controls showed simulated tremor-related activations in the right cerebellar lobule V.

Conclusions:

• Findings confirm bilateral cerebellar involvement in Essential Tremor.
• Specific tremor-related activations were identified in the bilateral somatomotor cerebellar regions: lobules V, VI, and VIII.