Are Hypometric Anticipatory Postural Adjustments Contributing to Freezing of Gait in Parkinson's Disease?

Walter Maetzler,Amie P. Hiller,Christian Schlenstedt,Martina Mancini,Günther Deuschl,Jay Nutt,Fay Horak

doi:10.3389/fnagi.2018.00036

Abstract

Introduction: This study aims at investigating whether impaired anticipatory postural adjustments (APA) during gait initiation contribute to the occurrence of freezing of gait (FOG) or whether altered APAs compensate for FOG in Parkinson’s disease (PD).Methods: Gait initiation after 30 s quiet stance was analyzed without and with a cognitive dual task (DT) in 33 PD subjects with FOG (PD+FOG), 30 PD subjects without FOG (PD-FOG), and 32 healthy controls (HC). APAs were characterized with inertial sensors and muscle activity of the tensor fasciae latae (TFL), gastrocnemius, and tibialis anterior was captured with electromyography recordings. Nine trials (of 190) were associated with start hesitation/FOG and analyzed separately.Results: PD+FOG and PD-FOG did not differ in disease duration, disease severity, age, or gender. PD+FOG had significantly smaller medio-lateral (ML) and anterio-posterior APAs compared to PD-FOG (DT, p < 0.05). PD+FOG had more co-contraction of left and right TFL during APAs compared to PD-FOG (p < 0.01). Within the PD+FOG, the ML size of APA (DT) was positively correlated with the severity of FOG history (NFOG-Q), with larger APAs associated with worse FOG (rho = 0.477, p = 0.025). ML APAs were larger during trials with observed FOG compared to trials of PD+FOG without FOG.Conclusions: People with PD who have a history of FOG have smaller ML APAs (weight shifting) during gait initiation compared to PD-FOG and HC. However, start hesitation (FOG) is not caused by an inability to sufficiently displace the center of mass toward the stance leg because APAs were larger during trials with observed FOG. We speculate that reducing the acceleration of the body center of mass with hip abductor co-contraction for APAs might be a compensatory strategy in PD+FOG, to address postural control deficits and enable step initiation.

Highlights

This study aims at investigating whether impaired anticipatory postural adjustments (APA) during gait initiation contribute to the occurrence of freezing of gait (FOG) or whether altered APAs compensate for FOG in Parkinson’s disease (PD)
People with PD who have a history of FOG have smaller ML APAs during gait initiation compared to PD subjects without FOG (PD−FOG) and healthy controls (HC)
We speculate that reducing the acceleration of the body center of mass with hip abductor co-contraction for APAs might be a compensatory strategy in PD who have FOG (PD+FOG), to address postural control deficits and enable step initiation

Summary

Introduction

This study aims at investigating whether impaired anticipatory postural adjustments (APA) during gait initiation contribute to the occurrence of freezing of gait (FOG) or whether altered APAs compensate for FOG in Parkinson’s disease (PD). Other studies did not find any differences between PD+FOG with PD−FOG in the on medication state in ML size of APAs during self-initiated and cued step initiation (Delval et al, 2014; Plate et al, 2016; de Souza Fortaleza et al, 2017). Other studies did not report any differences between PD+FOG and PD−FOG in number of APAs during self-initiated (medication on) (Plate et al, 2016) and cued stepping (medication on and off) (Delval et al, 2014; Plate et al, 2016; Cohen et al, 2017)

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