Objective: To investigate the frequency, clinical spectrum, and etiological correlates of movement disorders (MD) in early-onset ataxias.

Background: Early-onset ataxias are rare genetic disorders (1). MD are increasingly recognized as part of their clinical spectrum; however, pediatric data describing their phenomenology and etiological associations remain limited (2).

Method: We conducted a retrospective study in the Pediatric Neurology Department of the National Institute of Neurology, Tunis, Tunisia, between 2007 and 2025, including children (<18 years) with confirmed progressive ataxia. Demographic, clinical, and genetic data were reviewed. Associations between MD and etiologies were analyzed (significance threshold: p<0.05).

Results: Thirty-eight children with progressive ataxia were included. The male-to-female ratio was 0.56, and the median age at symptom onset was 18 months (IQR 14.3–48.0). MD were present early in the disease course in 34/38 patients (89.5%) but represented the initial presenting manifestation in only 2 patients (5.3%).

The most frequent diagnosis was ataxia-telangiectasia (AT) (22/38, 57.9%), followed by ataxia with vitamin E deficiency (AVED) (5/38, 13.2%), AT-like disease (3/38, 7.9%), Friedreich ataxia (2/38, 5.3%), spinocerebellar ataxias (2/38, 5.3%), hereditary spastic paraplegia type 75 (2/38, 5.3%), and other genetic ataxias (2/38, 5.3%).

Dystonia was the most frequent MD (28/38, 73.7%), followed by chorea (13/38, 34.2%), tremor (13/38, 34.2%), and myoclonus (3/38, 7.9%). Overlapping MD phenotypes were observed in 15 patients (39.5%). Among patients with dystonia, the distribution was generalized in 9/28, focal in 9/28, multifocal in 6/28, segmental in 4/28.

Chorea was strongly associated with the AT spectrum (12/13; p = 0.015). In contrast, tremor was significantly more frequent in AVED compared with other ataxias (4/5 vs 9/33, p = 0.038). Dystonia occurred across etiologies and was not significantly associated with a specific diagnosis.

Conclusion: MD constitute a prominent component of the clinical phenotype in pediatric progressive ataxias. Recognition of disorder-specific patterns, such as chorea in the ataxia-telangiectasia spectrum and tremor in AVED, may serve as important diagnostic clues, supporting earlier etiological identification and guiding targeted genetic testing.

References: 1. Sival DA, Garofalo M, Brandsma R, et al. Early Onset Ataxia with Comorbid Dystonia: Clinical, Anatomical and Biological Pathway Analysis Expose Shared Pathophysiology. Diagnostics. 2020;10(12):997. doi:10.3390/diagnostics10120997
2. Garcia Ruiz PJ, Mayo D, Hernandez J, Cantarero S, Ayuso C. Movement disorders in hereditary ataxias. Journal of the Neurological Sciences. 2002;202(1):59-64. doi:10.1016/S0022-510X(02)00211-3

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MDS Abstracts - https://www.mdsabstracts.org/abstract/movement-disorder-phenotypes-and-etiological-associations-in-genetic-early-onset-ataxias-a-pediatric-cohort-study/