Abnormal movement preparation in task-specific focal hand dystonia

Area of Science:

• Neuroscience
• Movement Disorders
• Brain Imaging

Background:

• Primary dystonia involves movement abnormalities.
• Previous studies suggest motor preparation deficits in dystonia.
• Functional magnetic resonance imaging (fMRI) has not yet specifically investigated movement preparation in focal hand dystonia (FHD).

Purpose of the Study:

• To identify brain activation abnormalities during the movement preparation phase in patients with task-specific focal hand dystonia (FHD).
• To compare brain activity during self-initiated and externally cued sequential finger movements between FHD patients and healthy controls.

Main Methods:

• Event-related functional magnetic resonance imaging (fMRI) was employed.
• Eighteen patients with task-specific focal hand dystonia (FHD) and 18 healthy subjects performed sequential finger movements.
• Motor performance and brain activation during movement preparation and execution were analyzed.

Main Results:

• FHD patients showed comparable motor performance and activation during movement execution to controls.
• Reduced brain activation was observed in FHD patients during movement preparation.
• Specifically, decreased activation was noted in the left premotor cortex/precentral gyrus, and in some conditions, the supplementary motor area, left mid-insula, and anterior putamen.

Conclusions:

• Task-specific focal hand dystonia (FHD) is associated with abnormalities in early motor control stages, particularly during movement preparation.
• These findings suggest deficits in the recruitment of motor programs rather than motor execution.
• The study proposes that errors in motor program recruitment, especially in complex, practiced movements, underlie the observed dystonic movements in FHD.