Side of Basal Ganglia Degeneration Influences Freezing of Gait in Parkinson's Disease

Although the role of hemispheric laterality in freezing of gait (FOG) remains a topic of debate, important new evidence has suggested that individuals with Parkinson's disease (PD) who experience freezing of gait (PD-FOG) may have decreased activity in the circuitry of the right fronto-parietal cortices, irrespective of the side of basal ganglia (BG) degeneration. Because the right hemisphere plays an important role in monitoring sensorimotor information during movements, and cortical regions interact with BG loops, one could expect that right cortical dysfunction in PD-FOG might be exacerbated by right sided BG damage (compared to left). The current study aimed to evaluate the influence of asymmetrical BG degeneration on self-paced gait in PD-FOG and PD-nonFOG. This study compared gait performance in predominantly left-or right-side affected PD patients with or without freezing of gait (LFOG = 11, RFOG = 10, LPD = 15, RPD = 11). Participants were instructed to walk 10 m on a GaitRite (R) carpet. As expected, gait parameters in PD-FOG were worse compared to PD-nonFOG. The spatiotemporal aspects of gait did not differ between LPD and RPD (nonFOG patients). Contrary to our hypothesis, RFOG (predominantly right side symptoms) had a shorter step length, increased step time variability and tended to walk slower compared with LFOG. Thus, rather than severely impaired right hemisphere circuitries exacerbating gait impairments, worse gait may be a consequence of both hemispheres being affected in PD-FOG.