Characterization of idiopathic Parkinson's disease subgroups using quantitative gait analysis and corresponding subregional striatal uptake visualized using ¹⁸F-FP-CIT positron emission tomography

Background: Gait disturbance is one of the most common symptoms among patients with idiopathic Parkinson's disease (IPD). Nevertheless, Parkinson's disease subtype clustering according to gait characteristics has not been thoroughly investigated. Research question: The aim of this study was to identify subgroups according to gait pattern among patients with IPD. Methods: This study included 88 patients with IPD who underwent ¹⁸F-fluorinated-N-3-fluoropropyl-2-β-carboxymethoxy-3-β-4-iodophenyl-nortropane positron emission tomography (¹⁸F-FP-CIT PET) and three-dimensional gait analysis (3DGA) between January 1, 2014 and December 31, 2016. We performed cluster analysis using temporal-spatial gait variables (gait speed, stride length, cadence, and step width) and divided patients into four subgroups. The kinematic and kinetic gait variables in 3DGA were compared among the four subgroups. Furthermore, we compared the uptake patterns of striatum among the four subgroups using ¹⁸F-FP-CIT PET. Results: The patients were clustered into subgroups based on gait hypokinesia and cadence compensation. Group 1 had decreased stride length compensating with increased cadence. Group 2 had decreased stride length without cadence compensation and wider step width. Group 3 had relatively spared stride length with decreased cadence. Group 4 had spared stride length and cadence. The uptake of posterior putamen was significantly decreased in Group 3 compared with Group 4. Significance: Gait hypokinesia and cadence can help to classify gait patterns in IPD patients. Our subgroups may reflect the different gait patterns in IPD patients.