What can we learn from freezing of gait in Parkinson's disease?

Freezing of gait (FOG) is defined as an episodic inability to generate effective stepping in the absence of any known cause, other than parkinsonism or high-level gait disorders. Substantial effort has been made to describe the clinical and kinematic characteristics of patients with FOG. In our review, we highlight the distinctive features of FOG in Parkinson's disease (PD) and apply the knowledge of its pathophysiology in PD to other clinical situations and conditions. It is possible that FOG in PD represents the ultimate break in the frontal lobe-basal ganglia-cerebellar-brainstem network that controls gait. Dysrhythmic and discoordinated gait with abnormal scaling of stride length, as well as gait festination, likely is the primary and continuous abnormality of "the gait network" in PD, and FOG represents its extreme and complete but transient disruption.