Objective: To detect freezing of gait (FoG) and quantify movement asymmetry from markerless full body motion capture with Microsoft Kinect™ during the execution of a 40 seconds “stepping in place” task.

Background: Asymmetry of limb movements is one characteristic and treatment-responsive feature of Parkinson’s disease (PD). Freezing of Gait (FoG) is a frequent and debilitating symptom in those with advanced stages of the disease and has been related to reduced mobility and fall risk. However, it often evades direct observation in standard clinical assessment and thus screening for FoG mainly relies on patient history.

Methods: We used Motognosis Labs in combination with Microsoft Kinect V2 to record execution of a stepping in place task for 40sec at self-selected speed and movement amplitude. We included 15 people with PD (PwPD) of different disease severity (UPDRS 7-55) and 50 healthy subjects (HC).

Cadence [steps/min] as well as knee and hand amplitudes in anterior-posterior (a-p) direction [m] were calculated using Kinect joint time series. Gait asymmetry was described for knee movement amplitudes as absolute differences [m] and differences as percentage of mean [%]. FoG was detected using windowed frequency analysis of knee movements.

Results: As expected, PwPD featured slower cadence (p=0.097) and smaller amplitudes of knee and hand excursions (p<0.001 and p<0.001) compared to HC. Although absolute side differences of knee excursion showed similar means and distributions in both groups, mean relative differences were increased in PwPD (15.89% (CI: -15.52 – 47.32) versus 6.54% (CI: -0.92 – 14.0) (HC), p = 0.041), consistent with movement asymmetry in independent clinical ratings. Step frequency analysis detected 7 FoG episodes in recordings from 4 PwPD but not in HC. For all patients, hesitation/freezing was also noted in independent clinical rating. [SM1] 

Conclusions: Using an easy-to-use commercially available infrared sensor and a clinically applicable stepping paradigm, we were able to extract quantitative descriptors for bradykinesia, hypokinesia as well as asymmetry of movement in accordance with clinical ratings. Interestingly FoG episodes were observed in four PwPD that were also detected by analysis of kinematic signals alone.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/instrumental-measurement-of-stepping-in-place-detection-of-asymmetry-and-freezing-of-gait/