Influence of white matter MRI hyper-intensities on acute l-dopa response in patients with Parkinson's disease.

Objective: To determine whether brain white matter hyperintensities (WMH) influence l-dopa response in Parkinson's disease (PD) patients.

Methods: We prospectively evaluated 60 PD patients with an acute l-dopa challenge test, and assessed motor performance with the Movement Disorders Society revised Unified Parkinson's Disease Rating Scale (MDS-UPDRS) during "ON" and "OFF" medication states. Magnetic resonance images were examined using a visual semi-quantitative rating scale for quantification and distribution analysis of WMH. l-dopa challenge test response was correlated to extent and location of WMH, to determine a potential association between them.

Results: Subjects with greater deep WMH burden, showed less response to l-dopa on axial motor symptoms (R = -0.35; p < 0.027), when tested with Part III of the MDS-UPDRS before and after acute levodopa challenge.

Conclusions: Results suggest WMH may affect response to l-dopa on axial function of PD patients, which could be due to either non-dopaminergic (cortico-basal ganglia) motor pathway disruption, or postsynaptic nigrostriatal pathway involvement.