Objective: To evaluate the natural history of Hereditary Spastic Paraplegia (HSPs) and to define sensitivity to change, minimal clinically important difference (MCID) and validity of different motor evaluation instruments.

Background: HSPs are a group of neurodegenerative diseases characterized by slow progressive spastic paraparesis, in which natural history is mostly unknown.

Method: The MOVESPAST study is constituted of two phases, the first one being a cross-sectional study and the second one a cohort study. All individuals who have HSP molecular diagnosis from a neurogenetic center in south Brazil were recruited. The Spastic Paraplegia Rating Scale (SPRS), the 6-minute walk test (6MWT), the 10 meters walk test (10MWT), and the Timed Up and Go test (TUG) were applied on baseline evaluation and will be applied after 12 and 24 months. Healthy controls matched to age and sex were also recruited for the cross-sectional phase.

Results: We have evaluated 32 HSP individuals, 25 of them were able to perform functional instruments (17 being SPG4), and 25 control individuals. Overall HSP patients and SPG4 patients presented worse performances than matched controls in all evaluated instruments (p<0.001 for all comparisons). There was a strong correlation between functional instruments and SPRS (R=0.726-0.803, p<0.001 for all comparisons) and disease stage (Rho=0.844-0.935, p<0.001 for all comparisons) for all HSPs. Among SPG4 individuals, there was moderate to strong correlations of 6MWT, 10WMT at maximum speed and TUG at self-selected speed with disease duration (R=0.501-0.751, p<0.05 for all comparisons), moderate to strong correlations of all instruments with SPRS (R=0.694-0.878, p<0.01 for all comparisons) and strong correlations of all instruments with disease stage (Rho=0.748-0.909, p<0.001 for all comparisons). MCID was estimated by the distributive method.

Conclusion: All timed functional instruments presented adequate criterion and construct validity for HSP. Such instruments are quick and easy to perform; are theoretically sensitive to change due to its quantitative nature; however, it can only be applied to ambulant individuals. Our results on the longitudinal phase of the study will help to understand better the natural history of HSPs and to design future clinical trials for these disorders.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/natural-history-of-movement-abnormalities-on-hereditary-spastic-paraplegia-validation-of-timed-functional-instruments/