Freezing of Gait in Parkinson's Disease: Its Pathophysiology and Pragmatic Approaches to Management.

BACKGROUND: Freezing of gait (FOG) in Parkinson's disease (PD) is poorly understood; however, with the established understanding of basal ganglia function, its manifestations should be more easily interpretable. This review examines freezing of gait (FOG) from such a perspective.
METHODS: A search of the MEDLINE and EMBASE databases from the year 2000 onward for review articles, focused on the pathophysiology of FOG, was used to determine current concepts. A previously established model of basal ganglia function was used to determine the concepts' validities. At the core of the model are deficits in motor set maintenance and timing cue production for automatic movement. It includes the shift between attention and automation to the predominant attention control of gait in PD.
RESULTS: The difficulties of the found concepts to explain FOG stem from failure to characterize different FOG components, from the assumption that all components share a similar pathophysiology, from a failure to separate basic deficits from compensatory mechanisms, and from the assumption that cognitive deficits are the cause of FOG rather than representing an inadequate compensation to FOG. Pragmatic approaches to management use the attention shift, with the provision of visual information about correct amplitude of step to correct initiation deficits, and motor blocks during gait. It also emphasizes the need to prevent step length reduction on turns, environmental situations, and cognitive overload.
CONCLUSION: The concept of automatic deficits in set maintenance and cue production best describe FOG manifestations in PD and, with the use of attention, the concept also provides pragmatic strategies for management.