Does metronome really help timing gait in parkinson's disease?

Introduction Timing gait disorders of Parkinson’s disease (PD) are characterized by unstructured gait vari- ability. Recently, the breakdown of the temporal organization of stride duration variability (i.e. long-range autocorrelations; LRA) was associated to dynamic instability in PD. To improve timing gait in PD, synchro- nization of walking with rhythmic auditory stimulation (RAS) like music or metronome is largely used in clinical settings. Purpose To assess the LRA modulation of PD gait pattern according to the structure of RAS. Method Nine patients performed overground walking trials at a comfortable speed while listening di erent structures of RAS (counterbalanced order across patients): isochronic, randomly uctuating, uctuating ac- cording to an LRA structure and no RAS. Each structure was adapted to the patient’s gait cadence as previ- ously measured in a 10 meter-walking test. Temporal organization (LRA) of stride duration variability, gait ca- dence, speed and stride length were measured on 512 consecutive gait cycles. e presence of LRA was based on scaling properties of the series variability (Hurst exponent) and the shape of the power spectral density (á exponent). ose measures were compared across the four conditions using a one-way-repeated ANOVA. Results Our results show that temporal organization of PD gait may be modulated using di erent audi- tory structures. Adequate correlation between LRA of gait and auditory cue indicates strong adaptation and synchronization of the gait to the RAS. However, LRA were systematically lower during auditory conditions compared to spontaneous walking session, up to the disappearance of LRA during isochronic RAS. Further- more, gait cadence, speed and stride length were not statistically di erent across di erent conditions. Discussion and conclusions Isochronic auditory stimuli (e.g. metronome) do not seem to be an optimal way to improve timing gait in PD, as it induces the disappearance of LRA. Future work will inve