In vivo evidence for GABA(A) receptor changes in the sensorimotor system in primary dystonia.

Background: Preclinical and clinical evidence suggests that impaired gamma-aminobutyric (GABA) control, leading to disinhibition within the sensorimotor system, might play a role in dystonia. Aim of this study is the in vivo assessment of the GABAergic system in dystonia using positron emission tomography (PET) and 11C-flumazenil, a selective GABAA receptor ligand. Methods: Fourteen subjects with primary dystonia (9 carriers of the DYT1 mutation and 5 sporadic cases) were compared to 11 controls, using a simplified reference tissue model to measure binding potential. Results: Voxel-based analyses showed a reduction in GABAA receptor expression/affinity both in DYT1 carriers and sporadic patients in primary motor and premotor cortex, primary and secondary somatosensory cortex, and in the motor component of the cingulate gyrus. Conclusions: Dysfunction of GABAA receptors in sensorimotor systems in primary (genetic and sporadic) dystonia supports the view that lack of GABAergic control may be associated with the generation of dystonic movements.