Objective: The Four Square Step Test (FSST) is brief and easy tool to assess dynamic balance to step over hindrance. Originally developed for older adults, the FSST has been widely used in neurological disorders such as post-stroke populations or multiple sclerosis.

Background: The purpose of this study were (1) to verify that individuals with early de novo Parkinson’s disease (PD) take more time to perform the FSST and (2) to identify which factors, cognitive status or cardinal motor symptom, may contribute more to the FSST performance.

Method: 35 PD patients and 17 controls who were diagnosed as essential tremor completed the FSST. PD patients included this study were newly diagnosed patients who have never taken dopaminergic drugs and also early stage patients who never had history of falling and who’s Hoehn & Yahr Stage (HYS) were within 2.5. The FSST is a timed test in which the individual is instructed to as rapidly and safely as possible step clockwise, then counter-clockwise over a low obstacle placed in a crosswise pattern on the floor. After a one-time rehearsal to make sure the participants understand the instructions, two consecutive trials were recorded and the fastest time was selected. Unified Parkinson ’s disease Rating Scale(UPDRS), gait analysis by GaitRite (CIR system, Inc.) and MoCA were also assessed in PD group.

Results: There were no significant differences of age and sex between PD and control group. The mean time of FSST performance was 8.20±1.61 seconds in PD which is significant difference compared to control group (7.13±1.10 seconds, P=0.018). In spearman correlations, MoCA had no significant correlation (rho=-0.015, p=0.935). Rather, UPDRS part III total score tend to be correlated (rho=0.307, p=0.073), especially PIGD sub-score had strongly significant correlation (rho=0.445, p=0.007). Among temporospatial gait parameters, percentage in gait cycle of double support time had significantly associated with FSST performance (rho=0.342, p=0.044), but other parameters including velocity or step length didn’t.

Conclusion: The FSST is a reliable, quick test in those with PD. In early stage, de novo PD patients, the FSST performance is contributed by postural instability rather than bradykinesia or executive function. The FSST in the clinic can be used easily to assess postural instability and further may help predict falling in early stage of PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/four-square-step-test-in-patients-with-early-de-novo-parkinsons-disease/