Spectrum of Movement Disorders in Early‐Onset Hereditary Spastic Paraplegia: A Study of 428 Cases

Background Movement disorders occur in early‐onset hereditary spastic paraplegia (HSP), but their prevalence, genotype associations, and clinical impact are not well defined. Objectives To delineate the spectrum and frequency of movement disorders across childhood‐onset HSP genotypes and assess associations with clinician‐ and caregiver‐reported outcomes. Methods We performed a cross‐sectional analysis of 428 children and young adults with molecularly confirmed HSP enrolled in a multicenter natural history study. Standardized clinical phenotyping and video examinations were reviewed. Movement and motor disorders (dystonia, ataxia, parkinsonism, tremor, choreoathetosis) were identified using predefined criteria. Associations with SPATAX‐EUROSPA disability stage (SPATAX), Spastic Paraplegia Rating Scale (SPRS; total and spasticity subscore), Modified Ashworth Scale, and Caregiver Priorities and Child Health Index of Life with Disabilities (CPCHILD) quality‐of‐life scores were analyzed with nonparametric tests and multivariable linear models adjusted for age and sex. Results Movement disorders were present in 27.6% (118/428) of participants; 22.8% of these had ≥2 movement disorders. Dystonia (16.4%) and ataxia (10.0%) predominated. Distinct genotype‐specific patterns were observed: dystonia in SPG4, SPG3A, and AP‐4‐HSP; parkinsonism in SPG11; and ataxia in SPG15, SPG76, SPG7, SPG5a, and SPG46. Presence of any movement disorder correlated with greater disability and motor burden and lower quality of life. In adjusted models, dystonia and parkinsonism were associated with higher SPATAX and SPRS scores, whereas ataxia and tremor correlated with lower scores; dystonia showed the largest decrement in CPCHILD. Conclusions Movement disorders are common, genotype‐specific, and clinically impactful features of childhood‐onset HSP. Routine screening and genotype‐tailored management of movement disorders, especially dystonia, may improve functional outcomes and quality of life.