An implantable medical device (IMD) is described capable of determining whether a patient is susceptible to freezing of gait events during ambulatory movement without the patient demonstrating an episode of freezing of gait. In one example, the IMD senses, via one or more electrodes, a bioelectrical signal of a brain of the patient while the patient performs movement associated with freezing of gait. The IMD determines, based on the bioelectrical signal, whether the patient is susceptible to freezing of gait while the patient is not experiencing an episode of freezing of gait. Further, upon detecting the movement associated with freezing of gait, the IMD delivers electrical stimulation therapy to the patient configured to suppress freezing of gait.