The Pattern and Stages of Atrophy in Spinocerebellar Ataxia Type 2: Volumetrics from <scp>ENIGMA</scp>‐Ataxia
Bibliographic record
Abstract
BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) is a rare, inherited neurodegenerative disease characterized by progressive deterioration in both motor coordination and cognitive function. Atrophy of the cerebellum, brainstem, and spinal cord are core features of SCA2; however, the evolution and pattern of whole-brain atrophy in SCA2 remain unclear. OBJECTIVE: We undertook a multisite, structural magnetic resonance imaging (MRI) study to comprehensively characterize the neurodegeneration profile of SCA2. METHODS: Voxel-based morphometry analyses of 110 participants with SCA2 and 128 controls were undertaken to assess groupwise differences in whole-brain volume. Correlations with clinical severity and genotype, and cross-sectional profiling of atrophy patterns at different disease stages, were also performed. RESULTS: Atrophy in SCA2 versus controls was greatest (Cohen's d >2.5) in the cerebellar white matter (WM), middle cerebellar peduncle, pons, and corticospinal tract. Very large effects (d >1.5) were also evident in the superior cerebellar, inferior cerebellar, and cerebral peduncles. In the cerebellar gray matter (GM), large effects (d >0.8) were observed in areas related to both motor coordination and cognitive tasks. Strong correlations (|r| > 0.4) between volume and disease severity largely mirrored these groupwise outcomes. Stratification by disease severity exhibited a degeneration pattern beginning in the cerebellar and pontine WM in preclinical subjects; spreading to the cerebellar GM and cerebro-cerebellar/corticospinal WM tracts; and then finally involving the thalamus, striatum, and cortex in severe stages. CONCLUSION: The magnitude and pattern of brain atrophy evolve over the course of SCA2, with widespread, nonuniform involvement across the brainstem, cerebellar tracts, and cerebellar cortex; and late involvement of the cerebral cortex and striatum. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".