Gait freezing in Parkinson's disease and the stride length sequence effect interaction

Abstract

Freezing of gait (FOG) has been identified as one of the main contributors to gait disturbances in Parkinson's disease. While the pathophysiology remains enigmatic, several factors such as step length and the sequence effect (step to step reduction in amplitude) may lead to the occurrence of FOG. It was hypothesized that by reducing step length, FOG episodes would present more frequently if a significant sequence effect (measured as a regression slope) was co-existent in the subject. Twenty-six participants with Parkinson's disease were separated clinically into a freezing (PD + FOG, n = 16) and non-freezing (PD-FOG, n = 10) group, with 10 age-matched control participants. Testing involved walking trials where preferred step length was set at 100%, 75%, 50% and 25% of normalized step length. The number of FOG episodes increased in the 50% condition and further increased in the 25% condition compared to other conditions. The participants with FOG also demonstrated a larger average regression slope, with significant differences in the 75%, 50% and 25% conditions when compared to the PD-FOG and control groups. There were no significant differences when comparing the slope of the PD-FOG and control group, indicating the reduced step length and the sequence effect may have led to the occurrence of FOG. These findings support the possible dual requirement of a reduced step length and a successive step to step amplitude reduction to lead to FOG.

Insights into the neural control of locomotion from walking through doorways in Parkinson's disease

“…For example, freezing behaviour is associated with a progressive reduction in step size (the sequence effect) set on top of a low baseline step length (hypokinesia) (Nieuwboer et al, 2001;Iansek et al, 2006;Chee et al, 2009). We have shown that doorways provoke decreases in velocity and stride length.…”

“…A parsimonious explanation for these disparate phenomena is that they result from involuntarily exaggerated responses to action-relevant visual information during walking in PD. As a result, visual information may promote or constrain walking depending on what possibilities it suggests for action: lines on the ground become readily stepped over but road-crossings produce an exaggerated slowing down which may in turn cause freezing episodes (Chee et al, 2009). …”

Gait bradykinesia in Parkinson’s disease: a change in the motor program which controls the synergy of gait

“…Most studies focused their analyses on steady-state walking, reporting that leg EMG activity is reduced, and that the results are basically consistent with those observed in arm and finger movements (Evarts et al 1981;Wing 1988;Cioni et al 1997;Chee et al 2009). In addition, it has been reported that the impairment of gait initiation is associated with the visuospatial cognitive environment (Azulay et al 1999;Cummings and Steven 1992;Naismith et al 2010).…”

Trastorno de la marcha en la enfermedad de Parkinson: freezing y perspectivas actuales

“…l congelamiento o "freezing" en la marcha (FM) es un fenómeno caracterizado por episodios transitorios de trastorno motor, mantenido algunos segundos, comúnmente observado en la enfermedad de Parkinson (EP), afectando a más de un tercio de los individuos [1][2][3] , siendo descrito por los pacientes como la sensación de tener los pies "pegados al suelo" 4 . Puede ser desencadenado al intentar iniciar y/o continuar la marcha, ante restricciones ambientales que exijan cambios en la velocidad, patrón o sentido del paso con o sin presencia de obstáculos o al caminar en espacios cerrados.…”