Effect of Rhythmic Haptic Stimulations on Long-Range Autocorrelations in Parkinson's Disease Gait Variability : A Comparison With Auditory Stimulations

1. BACKGROUND Parkinson's disease (PD) is the second most common degenerative neurological disease. PD induces gait disorders that lead to increased risk of falls. These falls seriously affect patients' quality of life and generate significant health care costs. Unfortunately, gait disorders do not respond well to drug treatments and their management is mainly based on rehabilitation treatment. The rehabilitation approach comprises two steps: a functional assessment of locomotor capacities followed by completion of a therapeutic physical exercise program.

Like heart rate, stride duration varies in the short and long term according to a complex dynamic of temporal variations. These variations present long-range autocorrelations (LRA): the stride duration does not vary randomly but in a structured way. The study of LRA is based on complex mathematical methods requiring recording of at least 256 consecutive gait cycles. LRA are altered in PD patients whose gait rhythm is excessively random. Alteration of LRA is correlated with neurological impairments (Hoehn & Yahr scale and UPDRS) and patients' locomotor stability (ABC scale & BESTest). Measurement of LRA would be the first available objective and quantitative biomarker of stability and risk of falling in patients with PD.

Guidelines concerning rehabilitation programs for PD patients are based on education (prevention of falls and inactivity,...), physical exercises, functional training (double task, complex tasks,...), learning, and adaptation strategies such as the use of rhythmic sensory cueing. Auditory Cueing (AC) has been used for years for clinical and research purposes and its effects on spatio-temporal gait parameters and LRA are known. Less is know regarding Haptic/Somatosensory Cueing (HC). A few research were conducted to study the influence of HC on PD spatio-temporal gait parameters but to the best of our knowledge, none has yet addressed its effects on LRA. The aim of this present study was to compare PD saptio-temporal gait parameters and LRA under three conditions : walking without cueing, walking with AC and walking with HC. 2. METHODS 2.1 Participants : 10 patients suffering from idiopathic Parkinson's Disease were recruited from the local community and from the Neurology and the Physical and Rehabilitation Medicine outpatient clinics of the Cliniques universitaires Saint-Luc (Woluwe-Saint-Lambert, Belgium).

2.2 Functional assessment: Before the expermientations starts, all participants underwent a non harmful assessment including clinical tests and questionnaires

PD patients: Age, height, weight, sex, most affected side, Movement Disorder Society-Unified Parkinson Disease Rating Scale (MDS-UPDRS), Mini Balance Evaluation Systems Test (Mini-BESTest), Simplified version of the Activities-specific Balance Confidence Scale (ABC-Scale), modified Hoehn & Yahr scale, Mini Mental State Examination (MMSE).