Digital Motor Outcomes Capture Upper Limb and Mild Stage Impairment in Hereditary Spastic Paraplegia.

Authors

Malin Schulze, Dominik Hermle, Robin Schubert, Pascal Barallon, Winfried Ilg, Rebecca Schüle, Ralf Reilmann, Matthis Synofzik, Andreas Traschütz

Published in

Neurology and therapy. Jun 15, 2026. Epub Jun 15, 2026.

Abstract

Digital motor outcomes may surpass the sensitivity of clinician-reported outcomes in hereditary spastic paraplegia (HSP), particularly in cases of mild upper limb impairment and early disease stages. We thus validated a trial-ready quantitative motor (Q-Motor) assessment of rapid alternating limb movement tasks against clinician-reported, patient-focused, and performance outcomes in HSP.
Exploratory single-center cross-sectional assessment in 41 patients with different HSP genotypes (age: 48 ± 14 years), with speeded foot tapping, diadochokinesia, and finger tapping measured by a high-resolution force transducer. Validation comprised discrimination from 48 age- and sex-matched controls; correlations to the Spastic Paraplegia Rating Scale (SPRS; mean: 18.6 ± 9.1), Friedreich Ataxia Rating Scale- Activities of Daily Living (FARS-ADL), and Nine-Hole Peg Test (9HPT); and stratification by functional stage (FARS stage: mild/moderate/severe = ambulatory/walking aid/wheelchair).
Foot tapping best discriminated patients with HSP from controls (e.g., frequency: area under the curve [AUC] = 0.94-0.96), and particularly captured HSP severity and functional impairment by measures of foot elevation and cumulative tap force (across all measures: |rho_SPRS|= 0.33-0.59; |rho_ADL|= 0.35-0.56). Speed measures of diadochokinesia and finger tapping captured functional impairment (|rho_ADL|= 0.32-0.60) and impaired dexterity (|rho_9HPT |= 0.53-0.77) in the upper limbs of patients with HSP-even in the mild stage, and with slowed finger tapping even in patients without upper limb pyramidal signs. Foot tapping measures were most sensitive in discriminating mild-stage impairment (AUC = 0.72-0.95) and predominantly changed between mild and moderate HSP, while upper limb measures of diadochokinesia and finger tapping predominantly changed from moderate to severe HSP.
Q-Motor captures motor impairment in HSP, even in the upper limbs and mild disease stages, and should be further evaluated as a possible trial outcome by longitudinal validation in genotypically stratified cohorts and mapping to patient experience.

PMID:
42298026
Bibliographic data and abstract were imported from PubMed on 16 Jun 2026.

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