Title:Imaging Studies in Focal Dystonias: A Systems Level Approach to Studying a Systems Level Disorder
Volume: 11
Issue: 1
Author(s): Anne J. Blood
Affiliation:
Keywords:
Dystonia, fMRI, DTI, PET, TMS, MEG, posture, basal ganglia, premotor, cerebellum, botulinum toxin, DBS
Abstract: Focal dystonias are dystonias that affect one part of the body, and are sometimes task-specific. Brain imaging
and transcranial magnetic stimulation techniques have been valuable in defining the pathophysiology of dystonias in
general, and are particularly amenable to studying focal dystonias. Over the past few years, several common themes have
emerged in the imaging literature, and this review summarizes these findings and suggests some ways in which these
distinct themes might all point to one common systems-level mechanism for dystonia. These themes include (1) the role
of premotor regions in focal dystonia, (2) the role of the sensory system and sensorimotor integration in focal dystonia, (3)
the role of decreased inhibition/increased excitation in focal dystonia, and (4) the role of brain imaging in evaluating and
guiding treatment of focal dystonias. The data across these themes, together with the features of dystonia itself, are
consistent with a hypothesis that all dystonias reflect excessive output of postural control/stabilization systems in the
brain, and that the mechanisms for dystonia reflect amplification of an existing functional system, rather than recruitment
of the wrong motor programs. Imaging is currently being used to test treatment effectiveness, and to visually guide
treatment of dystonia, such as placement of deep brain stimulation electrodes. In the future, it is hoped that imaging may
be used to individualize treatments across behavioral, pharmacologic, and surgical domains, thus optimizing both the
speed and effectiveness of treatment for any given individual with focal dystonia.
