Functional mobility assessment in Parkinson’s: A pilot feasibility study and a new methodological approach
Authors: Köchli Sabrina , Casso Isabel , Whyatt Caroline , Schmid Stefan , Ungerer Marietta , Delevoye-Turrell Yvonne , Rose Dawn 
Published: February 2024

Background
Parkinson’s disease (PD) is associated with motor impairments that negatively impact functional mobility (Armstrong & Okun, 2020). Functional mobility is “a person’s ability to move to accomplish activities of daily living” (Bouça-Machado et al., 2020). Whilst several assessment scales exist to evaluate PD, many focus on symptom severity or use speed as a proxy for quality of movement (e.g. Timed Up and Go; Buckley et al., 2019; Mirelman et al., 2019). Here we share the development of an integrated motion capture and pressure-sensitive gait mat sequence to assess functional mobility.
Design/Methods
To capture aspects of functional mobility accurately, we developed a new assessment protocol (FMA-P) to measure which aspects of movement differed between people with (n = 12) and without (n = 12) PD. The sequence involved rising from a chair, locomotion, turning, bending, picking up and placing an object (keys), and returning to sit down on the chair (mean of three trials).
Results
The mean age of our participants was 65.25 ± 7.8 years, 46% females. We found significant differences in locomotion such as a lower step ratio (p = 0.023), stride length (p < 0.001), and stride velocity (p = 0.019), as well as a higher double support time (p = 0.004), and stride length variability (p = 0.004) in people with PD (PwP) compared to aged-matched healthy participants. PwP showed a lower toe-off set angle (p = 0.042), lower foot height (p = 0.007), and a lower heel strike angle (p = 0.006) during locomotion. Further, a lower shoulder-elbow arm swing angular velocity (p=0.042), and a higher elbow-wrist arm swing angular velocity (p = 0.054) were observed in PwP compared to controls. Getting up from a chair was associated with a lower inclination amplitude in PwP compared to healthy controls (p = 0.047). In the turning section, we found a later onset of pelvis rotation in PwP (p = 0.034). More time was required for PwP to pick the keys up from the floor compared to controls (p = 0.002).
Discussion
The new measurement protocol could contribute to early diagnosis of PD, offering a quantitative evaluation of functional mobility. For example, reduced toe and heel offset angles may be early determinants of developing shuffling in later disease stages. Moreover, our findings provide objective and precise information about a variety of qualitative aspects of functional mobility. This approach can therefore be used to evaluate change over time thereby improving the evidence base of outcome variables for intervention studies. The FMA-P is of high clinical relevance to aid in the quantitative evaluation of clinical measures of motor impairment.
References
Armstrong, M. J., & Okun, M. S. (2019). Diagnosis and treatment of Parkinson disease. A review. JAMA, 232(6), 548-560. https://doi.org/10.1001/jama.2019.22360
Bouça-Machado, R., Duarte, G. S., Patriarca, M., Castro Caldas, A., Alarcão, J., Fernandes, R. M., Mestre, T. A.,, Matias, R., & Ferreira, J. J. (2020). Measurement instruments to assess functional mobility in Parkinson’s disease: A systematic review. Movement Disorders Clinical Practice, 7(2), 129-139. https://doi.org/10.1002/mdc3.12874
Buckely, C., Alcock, L., McArdle, R., Rana Zia Ur Rehman, R. Z. U., Del Din, S., Mazzà, C., Yarnall, A.J., & Rochester, L. (2019). The role of movement analysis in diagnosing and monitoring neurodegenerative conditions: Insights from gait and postural control. Brain Sciences, 9(2), Article 34. https://doi.org/10.3390/brainsci9020034
Mirelman, A., Bonato, P., Cmicioli, R., Ellis, T. D., Giladi, N., Hamilton, J. L., Hass, C. J., Hausdorff, J. M., Pelosin, E., & Almeida Q. J. (2019). Gait impairments in Parkinson’s disease. The Lancet Neurology, 18(7), 697-708. https://doi.org/10.1016/s1474-4422(19)30044-4