Sensory Cues for Freezing in Parkinson's Disease

Freezing of gait (FOG) is defined as a transient halt in motor activity, wherein the patient appears "as if nailed to the floor." It is a common phenomenon in Parkinson's disease (PD), both when medications are at their peak ("on state") and at their lowest effectiveness ("off state"). While "off" FOG often responds to dopaminergic medications, "on" FOG is a difficult to treat, causing significant distress for the patient, and elevating risk of falls and morbidity.

A few small studies have suggested that auditory and visual sensory cues, in the form of continuous stimuli such as a clicking metronome, music, or horizontal lines drawn the floor, may help patients with gait freezing. In this study, we aim to: (1) evaluate if stimuli (including visual, auditory as well as tactile cues) which are present only on patient triggering are effective for FOG in PD; (2) investigate if presentation of unexpected cues, in the form of randomized sensory stimuli, are more effective that anticipated cues.

Participants will include patients diagnosed with PD, stabilized on drug therapy, with adequate vision, hearing, and mentation to respond to cuing, and experiencing "on" FOG. Patients will be evaluated during a single session. A small device which we have developed will be placed around the neck, and emit either repetitive beeping, a flashing line on the floor, or a slight vibration felt over the neck when the patient presses a button on the front panel in response to FOG. Participants will be videotaped walking a 15 m strip with: (1) no cues; (2) auditory cues only; (3) visual cues only; (4) tactile cues only; and (5) randomized cues. The order in which patients receive the cues will be randomized.

A reviewer will watch the videotape with sound off so that they will be blinded to the cues. The Total Time, Freezing Time (duration of walk in which patient experiences freezing, Walking Time (duration of walk during which patient is not experiencing freezing), and Average Duration of Freeze will be recorded for each walk.