An updated definition of freezing of gait

Freezing of gait (FOG) is among the most debilitating symptoms of Parkinson disease and related disorders, often resulting in falls and a loss of independence. FOG has an episodic and heterogeneous nature that makes it difficult to measure and treat. The field currently lacks a consensus on how to precisely define this phenomenon. For this reason, the International Consortium for Freezing of Gait convened a group of experts to establish an updated 'clinical' definition of FOG for use in the clinical setting and a 'technical' definition for assessors to use when scoring FOG episodes from video recordings as an outcome in fundamental research and clinical trials. Guidelines on how to classify people with Parkinson disease into subgroups of those with or without FOG (non-FOG) are also provided. This position paper presents these new definitions and guidelines, offering a foundation for harmonizing the study and management of FOG.