TreatHSP Platform: Adaptive Natural History Platform for Ataxias, HSPs, and Spastic Ataxias

The modified Spastic Paraplegia Rating Scale (mSPRS) is a clinician-reported outcome measure assessing disease severity in hereditary spastic paraplegia and related spastic movement disorders. It evaluates functional mobility, spasticity, muscle strength, pain and bladder function. The mSPRS is adapted from the original Spastic Paraplegia Rating Scale to improve feasibility and sensitivity to change in longitudinal studies. It can be applied in individuals aged 5 years and older, with higher scores indicating greater disease severity.

The mSPRS serves as the primary outcome measure for the assessment of disease severity in all participants with hereditary spastic paraplegia.

The Scale for the Assessment and Rating of Ataxia (SARA) is a standardized clinician-reported outcome measure used to quantify the severity of ataxia. It assesses key domains including gait, stance, sitting, speech disturbance, limb coordination, and fine motor control. The SARA provides a global measure of ataxia-related motor impairment and is widely used in both clinical practice and longitudinal research studies. The SARA is applied in study participants aged 8 years and older, with higher scores indicating greater ataxia severity. The SARA serves as the primary outcome measure for the assessment of disease severity in all participants with ataxia.

SPAXCOM is a clinician-reported composite outcome measure developed to assess disease severity in individuals with spastic ataxia. It integrates key motor and functional domains relevant to spastic-ataxic phenotypes, including gait and balance, coordination, spasticity, and functional mobility. SPAXCOM is designed to capture the combined contribution of pyramidal and cerebellar dysfunction and to provide a sensitive measure of disease severity and progression in spastic ataxia. Higher scores indicate greater disease severity. SPAXCOM serves as the primary outcome measure for participants with spastic ataxia.

The Friedreich Ataxia Rating Scale - Activities of Daily Living (FARS-ADL) assesses the impact of neurological impairment on everyday functioning, including walking, balance, speech, hand function, and self-care. In this study, both a clinician-reported (ClinRO) version and a patient-reported (PROM) version of the FARS-ADL are used to capture functional limitations from complementary perspectives and are applied in study participants aged 8 years and older. Although originally developed for Friedreich ataxia, the FARS-ADL is applicable across a range of ataxic and spastic movement disorders. Higher scores indicate greater functional impairment and reduced independence in daily activities.

INAS-PLUS is a clinician-reported inventory, derived from the original Inventory of Non-Ataxia Signs (INAS) and expanded by additional items, used to quantify the burden of neurological signs beyond core ataxia features in spastic and spastic-ataxic disorders.

The Medical Research Council (MRC) Sum Score is a clinician-reported measure of global muscle strength based on standardized manual muscle testing across selected muscle groups. Individual muscle grades are summed to provide an overall estimate of muscle strength, with lower scores indicating greater weakness.

The TreatHSP Quality of Life (TreatHSP-QoL) questionnaire is a disease-specific patient-reported outcome measure assessing health-related quality of life, including physical, functional, and psychosocial aspects, and is used in adults aged 18 years and older with hereditary spastic paraplegia and spastic ataxia.

The Caregiver Priorities and Child Health Index of Life with Disabilities (CPCHILD) is a caregiver-reported outcome measure developed for children and adolescents with motor disabilities. In this study, the CPCHILD is applied in all children aged 5 to 12 years, as well as in older individuals with cognitive impairment who are unable to reliably complete self-reported questionnaires.

The Friedreich Ataxia Rating Scale - Functional Staging (FARS-FS) is an ordinal measure of functional disease severity based on mobility and independence in activities of daily living. In this study, both a clinician-reported (ClinRO) version and a patient-reported (PROM) version of the FARS-FS are used to capture functional status from complementary perspectives. The FARS-FS serves as an anchor measure to support the determination and interpretation of clinically meaningful change in primary and secondary outcome measures over time.

SPATAX Disability Stage is a clinician-reported ordinal staging system that categorizes overall disability based on mobility and functional dependence. It provides a global measure of disease severity and is used in this study as an anchor measure to support the interpretation of clinically meaningful change in primary and secondary outcomes.

Clinical Global and Domain-Specific Impression of Severity and Change are clinician-reported assessments capturing overall disease severity and longitudinal change, as well as change within specific functional domains. The selected domains reflect disease impacts prioritized by individuals with SPAX diseases for their relevance to everyday life. These measures are used as anchor measures to contextualize and determine meaningful change in primary and secondary outcome measures.

Patient-reported Global and Domain-Specific Impression of Severity and Change are self-reported assessments capturing overall disease severity and longitudinal change, as well as change within specific functional domains. The selected domains reflect disease impacts prioritized by individuals with SPAX diseases for their relevance to everyday life. These patient-reported measures are used as anchor measures to support the interpretation and determination of clinically meaningful change in primary and secondary outcome measures.

The Functional Mobility Scale (FMS) is a clinician-reported measure of functional walking ability that classifies mobility across different distances and everyday environments. It provides an ordinal assessment of functional mobility and is used in this study as an anchor measure to support the interpretation of clinically meaningful change in primary and secondary outcome measures.

The Gross Motor Function Classification - MLD (GMFC-MLD) is a clinician-reported ordinal classification system used to describe gross motor function and mobility limitations in children. It categorizes functional abilities based on age-appropriate motor skills and need for assistance. In this study, the GMFC-MLD is used as an anchor measure to support the interpretation of clinically meaningful change in outcome measures in children aged 5 to 12 years.

The Mobility Change Questionnaire is a patient- or observer-reported anchor measure assessing perceived change in walking ability over the preceding week compared with the previous study visit. It captures mobility-related domains including walking distance and speed, effort, balance confidence, fear of falling, and overall walking ability. Depending on age and cognitive status, the questionnaire is completed by the participant or an observer and is used to support the interpretation of clinically meaningful change in primary and secondary outcome measures.

Achievement of key developmental motor milestones (unsupported sitting, unsupported standing, assisted walking, unsupported walking) will be assessed via caregiver/patient report. For each milestone, achievement status will be recorded as yes/no/unknown. Age at achievement will be reported in months for milestones confirmed as achieved. Where an exact age cannot be recalled, this will be noted as either delayed-but-unrecalled or achieved-at-normal-age-but-unrecalled.

Loss of previously achieved motor function will be assessed via caregiver/patient report across four regression milestones: new requirement for sitting support, new requirement for standing support, new requirement for a walking aid (used for >50% of walking activity), and new requirement for a wheelchair (used for >50% of locomotion). For each milestone, status will be recorded as yes/no/unknown, with the calendar year of onset documented where applicable.