Freezing of gait: moving forward on a mysterious clinical phenomenon

Abstract

Freezing of gait (FoG) is a unique and disabling clinical phenomenon characterised by brief episodes of inability to step or by extremely short steps that typically occur on initiating gait or on turning while walking. Patients with FoG, which is a feature of parkinsonian syndromes, show variability in gait metrics between FoG episodes and a substantial reduction in step length with frequent trembling of the legs during FoG episodes. Physiological, functional imaging, and clinical-pathological studies point to disturbances in frontal cortical regions, the basal ganglia, and the midbrain locomotor region as the probable origins of FoG. Medications, deep brain stimulation, and rehabilitation techniques can alleviate symptoms of FoG in some patients, but these treatments lack efficacy in patients with advanced FoG. A better understanding of the phenomenon is needed to aid the development of effective therapeutic strategies.

Neuromuscular correlates of subthalamic stimulation and upper limb freezing in Parkinson’s disease

“…Accordingly, we inspected each individual EMG data set for tremor and, consecutively, one patient had to be excluded when tremor solely occurred during StimOn interference. Generally however, the ULF phenomenon in this study and in rich previous work is separable from action tremor despite of its 'trembling-like' nature for several major reasons that were also conceived in our study (Barbe et al, 2014;Nieuwboer et al, 2009;Nutt et al, 2011): during ULF the power spectrum of the biomechanical signal traces did not show a distinct peak at tremor frequency (unlike the excluded measurement of iPD8, who showed a tremor peak). Characteristic for ULF, the power spectrum of the biomechanical signal showed broader low-frequency activity (exemplary data provided as Supplementary material, Section A).…”

“…Hitherto, there is no 'gold standard' in identifying ULF episodes and in defining an accurate onset. This is inherent to research on freezing phenomena that develop with variable time delay after a regular movement and may be preceded by a short period of movement slowing and amplitude decrease before 'trembling-in-place-like-freezing' emerges (Nutt et al, 2011). Therefore, the most reproducible and reliable way to standardize the segmentation of our time-frequency analyses was to time-lock to the last regular finger tap before ULF emerged.…”

“…Functional imaging pointed to both cortical and subcortical network abnormalities in freezers, and implicated the subthalamic nucleus, as well as the mesencephalic locomotor region and higher-order cortical areas in freezing pathophysiology (Herman et al, 2013;Shine et al, 2013b). Much less is known about the electrophysiological neuromuscular mechanisms behind freezing (Nutt et al, 2011).…”

Primary Progressive Freezing: does it stand on its own?

“…Disturbances in frontal cortical regions, the basal ganglia, and the midbrain locomotor region have been implicated [5]. The nigrostriatal dopaminergic system is thought not to be involved, and the affected patients do not respond to dopaminergic medications [1].…”

Effects of subthalamic and nigral stimulation on gait kinematics in Parkinson's disease

“…This is critical, as temporal regulation of the gait cycle is crucial to PD gait disturbance, in particular to PD patients with freezing of gait (FOG). Temporal abnormalities of locomotor integration may increase susceptibility to FOG (8). In this sense, several temporal parameters of gait, including temporal gait variability and asymmetry, are deteriorated in PD freezers (9,10).…”