The contribution of optic flow to freezing of gait in left- and right-PD: Different mechanisms for a common phenomenon?

Abstract

It has been recently hypothesized that impaired processing of optic flow may be related to FOG, especially in PD patients with left-side symptomatology (LPD). The current preliminary study examined the frequency of FOG episodes in LPD and RPD while the availability of optic flow was manipulated during gait. Twelve patients (6 FOG-L, 6 FOG-R) completed walking trials in two conditions (optic flow or no optic flow). Results revealed that FOG frequency was similar between groups when optic flow was not available, however, optic flow provided by walking toward an illuminated doorframe, lead to a three-fold increase in FOG episodes in only the LPD (compared to RPD). These findings suggest that LPD might have deficits in perceiving or processing optic flow when passing through doorways. Thus, it is important to consider how sensory processing mechanisms may contribute to severe gait disturbances such as FOG.