Identification of anatomical locations: its relevance for vibrotactile perception of individuals with Parkinson's disease

Background: Vibrotactile input is a useful sensory cue for individuals with Parkinson's Disease (PD) to overcome freezing of gait (FoG). For this input to serve as a cue, its accurate perception is required. This needs the input to be delivered at an anatomical location where it can be perceived. This is particularly true for individuals with PD whose tactile perception differs from that of healthy individuals. Literature indicates choice of various anatomical locations e.g., Finger, Wrist, Thigh, Shin, Calf, Ankle, Achilles Tendon, Heel and torso for the application of vibrotactile stimulation. Though studies have focused on the comparison of the vibrotactile perception (based on feedback) at various anatomical locations, yet these have involved only healthy individuals. However, such exploration remains as majorly untouched for individuals with PD. Methods: To bridge this gap, here we have conducted a study using our vibrotactile stimulation system while involving twenty-one individuals with PD to understand the choice of anatomical location with regard to vibrotactile perception. In addition, our study involved twenty-one age-matched healthy individuals to understand possible differences if any in vibrotactile perception between the two groups of participants. Results: Our results showed that for the healthy participants, both 'Wrist' and 'Thigh' were equally strong anatomical locations with regard to vibrotactile perception that were correctly identified 100% of the time closely followed by ‘Finger’ for which the correct identification was 98% of the time with correct identification for all these three locations being statistically (p < 0.05) higher than the other locations. In contrast, for individuals with PD, the 'Thigh' emerged as a strong candidate anatomical location with regard to vibrotactile perception even for those with severity of symptoms (based on clinical measure) that was correctly identified 96% of the time followed by ‘Wrist’ for which the correct identification was 92% of the time with the correct identification for only the ‘Thigh’ being statistically (p < 0.05) higher than all the other locations (except ‘Wrist’). Conclusion: This finding is clinically significant in deciding the right anatomical location to offer vibrotactile cues for it to be correctly perceived by one with PD, providing assistance to overcome FoG.