The pathophysiological mechanisms underlying freezing of gait in Parkinson's Disease.

Freezing of gait is a paroxysmal phenomenon most commonly found in patients with advanced Parkinson's Disease. The pathophysiological mechanisms underlying this behaviour remain uncertain despite a well-characterised phenotype. Freezing behaviour extends beyond gait to affecting speech and upper limb function, suggesting that there is likely to be a universal mechanism underlying the phenomenon. This paper identifies the essential features required for a comprehensive model of freezing and evaluates a number of hypotheses that seek to explain the phenomenon. It appears likely that the pathophysiology of freezing involves context-dependant dysfunction across multiple levels of the neurological system, including cortical, subcortical and brainstem regions. Crown