Gait initiation impairment in patients with Parkinson’s disease and freezing of gait

Abstract

ObjectiveFreezing of gait (FOG) is a sudden episodic inability to produce effective stepping despite the intention to walk. It typically occurs during gait initiation or modulation and may lead to falls and loss of independence. We assessed gait initiation (GI) changes in parkinsonian patients suffering from FOG when off dopaminergic medications, removing correlations with anthropometric measurements, the base of support, and initial stance posture. We also addressed the temporal pattern of segmental body movements subserving gait initiation.MethodsWe studied 23 subjects with Parkinson’s disease (PD) and FOG (PDF), 20 patients with PD and no previous history of FOG (PDNF), and 20 healthy controls (HC). Kinematic and dynamic analysis of anticipatory postural adjustments (imbalance, unloading, stepping phase) was performed while patients were starting gait from upright standing after a self-selected period, to avoid any effect of cueing on gait initiation.ResultsThe center of pressure (CoP) displacement and velocity during imbalance showed a significant impairment in both PDNF and PDF, more prominent in the latter patients. Several measurements were specifically impaired in PDF patients, especially the CoP displacement along the anteroposterior axis during unloading. The pattern of segmental center of mass (SCoM) movements during gait initiation did not show any differences between groups, but had high inter-subject variability. The standing postural profile preceding GI did not correlate with outcome measurements.ConclusionsOur results showed impaired motor programming at gait initiation in parkinsonian patients. The more prominent deterioration of unloading in PDF patients might suggest impaired processing and integration of somatosensory information subserving gait initiation. The unaltered temporal movement sequencing of SCoM in both PDNF and PDF might indicate some compensatory cerebellar mechanisms triggering time-locked models of body mechanics in PD.