Pallidal Deep Brain Stimulation Reduces Sensorimotor Cortex Activation in Focal/Segmental Dystonia

Area of Science:

• Neuroscience
• Movement Disorders
• Neurosurgery

Background:

• Deep brain stimulation of the globus pallidus internus (GPi-DBS) is a recognized treatment for various dystonia types.
• However, its precise impact on brain function, especially in focal and segmental dystonia, requires further investigation.
• Clinical benefits of GPi-DBS are often delayed and can persist for days or weeks after stimulation cessation.

Purpose of the Study:

• To investigate the effects of GPi-DBS on neural activity during rest and motor tasks in focal and segmental dystonia.
• To differentiate GPi-DBS effects from changes in muscle contraction due to therapy.
• To compare brain activity in patients with and without GPi-DBS during motor tasks.

Main Methods:

• The study included 14 patients with cervical dystonia, divided into two groups: 6 with GPi-DBS and 8 without (control).
• Regional cerebral blood flow was measured using H2(15)O PET during rest and a motor task.
• The motor task involved using a nondystonic hand to mitigate confounding factors from dystonic muscle activity.

Main Results:

• Patients with GPi-DBS exhibited reduced resting activity in a prefrontal network compared to controls.
• During the motor task, GPi-DBS patients showed lower sensorimotor cortex activity than controls.
• Task-induced motor network activation was less extensive in GPi-DBS patients, particularly in the stimulation ON state.

Conclusions:

• GPi-DBS appears to normalize sensorimotor and prefrontal hyperactivity in focal and segmental dystonia, mirroring effects seen in generalized dystonia.
• The findings suggest similar underlying mechanisms for GPi-DBS efficacy across different dystonia subtypes.
• Crucially, neuroimaging evidence indicates that these normalizing effects extend even when GPi-DBS is turned off, a novel finding.