Objective: To evaluate gait asymmetry using velocity-dependent gait analysis and compare to UPDRS asymmetries.

Background: Motor impairment, including gait impairment, in patients with Parkinson’s disease (PD) frequently manifests asymmetrically. Previous studies have suggested that gait asymmetry may be a contributing factor to freezing of gait (FOG) and falls. It is unclear whether asymmetry found in the cardinal signs of PD (tremor, rigidity, bradykinesia) is a major determinant of asymmetry represented in gait. We sought to use velocity-dependent gait analysis using a pressure-sensitive gait walkway to analyze relationships between gait asymmetry and asymmetry in PD motor signs and to relate them to clinically relevant gait-related disability.

Methods: Using a 16 x 2 foot walkway, we collected gait metrics [step-by-step stride length, step length, swing time, stance time, stride velocity and cadence] in 19 PD patients and 11 healthy control (HC) subjects across multiple walking speeds. In PD patients, we also collected MDS-UPDRS, PDQ-39, FOG-Q, and frequency of falls. We analyzed step by step metrics, preserving left-right steps separately, as a function of velocity and generated regression curves (gait curves). Asymmetry of bradykinesia (A_B) and rigidity (A_R) was calculated as a difference in right/left sums of MDS-UPDRS III items 4-8 or item 3 respectively.  Severity of gait curve asymmetry was binarized as either mild or moderate based upon area calculated between left and right gait curves in all parameters.

Results: In four HC subjects, we found minor asymmetry in step length; otherwise no gait curves were asymmetric. By contrast, in eleven PD subjects we found left/right asymmetries across all gait curves, with unique configurations in many subjects.  Global gait curve asymmetry was ranked across subjects according to laterality and severity. Global gait curve asymmetry was uncorrelated with A_B or with A_R.  Global gait curve asymmetry was correlated strongly with falls but only weakly with FOG-Q scores.

Conclusions: Our data suggests that global gait asymmetry in PD subjects is uncorrelated with bradykinesia asymmetry and may not be a strong predictor of FOG. The correlation between self-reported fall frequency and gait asymmetry further suggests that asymmetry in itself is an important clinical metric that justifies further studies.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gait-asymmetry-and-parkinsons-disease/