Primary dystonia: conceptualizing the disorder through a structural brain imaging lens

Background: Dystonia is a hyperkinetic movement disorder characterized by involuntary, repetitive twisting movements. The anatomical structures and pathways implicated in its pathogenesis and their relationships to the neurophysiological paradigms of abnormal surround inhibition, maladaptive plasticity, and impaired sensorimotor integration remain unclear.

Objective: We review the use of high-resolution structural brain imaging using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) techniques for evaluating brain changes in primary torsion dystonia and their relationships to the pathophysiology of this disorder.

Methods: A PubMed search was conducted to identify relevant literature.

Results: VBM and DTI studies produced somewhat conflicting results across different forms of primary dystonia and reported increases, decreases, or both in gray matter volume and white matter integrity. However, despite the discrepancies, these studies are consistent in revealing brain abnormalities in dystonia that extend beyond the basal ganglia and involve the sensorimotor cortex and cerebellum.

Discussion: Although limited to date, structural magnetic resonance imaging (MRI) studies combined with functional brain imaging and neurophysiological modalities begin to establish structural-functional relationships at different levels of the abnormal basal ganglia, cortical, and cerebellar networks and provide clues into the pathophysiological mechanisms that underlie primary dystonia. Cross-disciplinary studies are needed for further investigations of the interplay between structural-functional brain abnormalities and environmental and genetic risk factors in dystonia patients.