Gait impairments in Parkinson's disease

Summary

Gait impairments are among the most common and disabling symptoms of Parkinson's disease. Nonetheless, gait is not routinely assessed quantitatively but is described in general terms that are not sensitive to changes ensuing with disease progression. Quantifying multiple gait features (eg, speed, variability, and asymmetry) under natural and more challenging conditions (eg, dual-tasking, turning, and daily living) enhanced sensitivity of gait quantification. Studies of neural connectivity and structural network topology have provided information on the mechanisms of gait impairment. Advances in the understanding of the multifactorial origins of gait changes in patients with Parkinson's disease promoted the development of new intervention strategies, such as neurostimulation and virtual reality, aimed at alleviating gait impairments and enhancing functional mobility. For clinical applicability, it is important to establish clear links between specific gait impairments, their underlying mechanisms, and disease progression to foster the acceptance and usability of quantitative gait measures as outcomes in future disease-modifying clinical trials.

Introduction

The typical pathological manifestations of Parkinson's disease (bradykinesia, rigidity, and reduced amplitude and automaticity of movement) affect the gait patterns of patients with the disease. Patients have reduced gait speed and step length, increased axial rigidity, and impaired rhythmicity. Gait problems worsen as the disease progresses, which is a major disease burden that markedly affects independence and quality of life (panel).1, 8 Although dopaminergic medications improve certain aspects of walking such as velocity and step length, temporal characteristics and episodic symptoms such as freezing of gait, defined as the sudden inability to continue walking despite the intent to maintain locomotion, have responses that are much more variable.2, 20 Gold-standard dopaminergic treatments also create multiple challenges that can further impair gait, including fluctuations in motor response (so-called wearing off) and dyskinesia.⁴ Thus, optimal evaluation and treatment of alterations in gait in patients with Parkinson's disease demands an understanding of the multiple mechanisms and factors that contribute to these problems.

The current understanding of gait impairments in patients with Parkinson's disease is based mainly on cross-sectional studies that do not provide insights into individual gait changes associated with disease progression.3, 7, 8 The rare use of quantitative assessment of gait (eg, speed and variability) in the routine clinical examination and poor understanding of the underlying mechanisms limits the use of gait measures as viable outcomes for assessing disease progression and effects of treatment. Advances in wearable technology and imaging techniques have generated knowledge relevant to assessment, understanding of mechanisms, and treatment of gait impairments in patients with Parkinson's disease. Low-cost sensing technology (eg, accelerometers and gyroscopes) is rapidly replacing complex camera-based motion-capture systems, allowing clinicians to quantitatively assess gait not only in the clinic but also during daily living activities in the home and community settings. This method of measurement provides valuable information on habitual function, motor fluctuations, and response to medications. Neuroimaging techniques that record neural activity during walking have advanced the understanding of the mechanisms causing aberrant gait patterns in patients with Parkinson's disease, leading to the design of more effective clinical interventions.21, 22, 23, 24, 25, 26

This Review evaluates the advances made in three related aspects of gait impairments in patients with Parkinson's disease: assessment, mechanisms, and interventions to improve gait. The Review highlights the gaps in knowledge and provides insights that might lead to new discoveries and innovations to improve clinical decisions and treatments.