Neuroimaging as a window into gait disturbances and freezing of gait in patients with Parkinson's disease.

Neuroimaging has been applied to better understand the neural mechanisms underlying gait disturbances in Parkinson's disease (PD). In the present paper, we review studies that used neuroimaging methods to investigate mobility, walking and freezing of gait (FOG) in PD, focusing on the recent literature. Examination of these studies suggests that gait changes in PD are due to widespread alterations in the structure and function of the brain that go beyond the basal ganglia. For example, cortical structures including the frontal and parietal lobes, the mesencephalic locomotor region and specifically, the pedunculopontine nucleus, all apparently play important roles in the control of gait in PD. Nonetheless, there are some significant inconsistencies across the different studies and many questions remain regarding the precise pathological processes that contribute to gait disturbances, in general, and to FOG, more specifically. A discussion of new insights into the neural mechanisms underlying gait disturbances are presented along with a summary of the disadvantages and limitations of the existing techniques and suggestions for future directions.