Increased prefrontal volume in PD with levodopa-induced dyskinesias: a voxel-based morphometry study.

Levodopa-induced dyskinesias represent disabling complications from long-term therapy with dopaminergic drugs for treating Parkinson's disease (PD). Although several neuroimaging studies have reported altered striatofrontal function that contributes to the emergence of these motor complications, the neuroanatomical correlates of this disorder are still unknown. Optimized voxel-based morphometry (VBM) was applied to the MRI brain images of 36 PD patients with levodopa-induced dyskinesias, 36 PD patients without levodopa-induced dyskinesias, and 32 age- and sex-matched controls. The VBM analysis comparing dyskinetic and nondyskinetic groups provided evidence of increased gray matter volume of the bilateral inferior frontal gyrus in dyskinetic patients, a finding that was more evident in patients with early-onset PD. No significant differences were detected in the dyskinetic and nondyskinetic groups when compared with the controls. Our findings suggest that the presence of dyskinesias in patients with PD is characterized by an aberrant neural plasticity that could play a role in the pathophysiology of these motor complications.