A medical system comprising: means (24, 26) for sensing a first amplitude of a bioelectrical signal of a brain of a patient while the patient is not moving, wherein the bioelectrical signal of the brain of the patient is a Beta signal of the brain of the patient comprising a frequency of about 11 Hertz to about 30 Hertz, and means (24, 26) for sensing a second amplitude of the bioelectric signal when the patient performs movement associated with freezing of gait; and means for determining, based on a difference between the first amplitude and the second amplitude, whether the patient is susceptible of freezing gait; and characterised by means for, upon determining that the patient is susceptible of freezing of gait, storing in the memory of an implantable medical device an electrical stimulation therapy program with a stimulation frequency range of 60Hz to 100Hz to suppress freezing of gait; means for monitoring movement of the patient; means for detecting when the patient performs a movement associated with freezing of gait; means for controlling the medical device to deliver a first electrical stimulation therapy at a first frequency to the patient; and means for switching, in response to the detected movement associated with freezing of gait, from controlling the medical device to deliver the first electrical stimulation therapy at the first frequency to the patient to controlling the medical device to deliver a second electrical stimulation therapy at a second frequency to the patient, the second electrical stimulation therapy being the stored electrical stimulation therapy program to suppress freezing of gait. means (24, 26) for sensing a first amplitude of a bioelectrical signal of a brain of a patient while the patient is not moving, wherein the bioelectrical signal of the brain of the patient is a Beta signal of the brain of the patient comprising a frequency of about 11 Hertz to about 30 Hertz, and means (24, 26) for sensing a second amplitude of the bioelectric signal when the patient performs movement associated with freezing of gait; and means for determining, based on a difference between the first amplitude and the second amplitude, whether the patient is susceptible of freezing gait; and characterised by means for, upon determining that the patient is susceptible of freezing of gait, storing in the memory of an implantable medical device an electrical stimulation therapy program with a stimulation frequency range of 60Hz to 100Hz to suppress freezing of gait; means for monitoring movement of the patient; means for detecting when the patient performs a movement associated with freezing of gait; means for controlling the medical device to deliver a first electrical stimulation therapy at a first frequency to the patient; and means for switching, in response to the detected movement associated with freezing of gait, from controlling the medical device to deliver the first electrical stimulation therapy at the first frequency to the patient to controlling the medical device to deliver a second electrical stimulation therapy at a second frequency to the patient, the second electrical stimulation therapy being the stored electrical stimulation therapy program to suppress freezing of gait.