Spectrum of Dystonia in Spinocerebellar Ataxia

Spinocerebellar ataxias (SCAs) are a diverse group of inherited disorders characterized by progressive cerebellar dysfunction. Beyond the classic ataxic features, dystonia is an important manifestation across both common and uncommon SCA subtypes. The complete clinical spectrum, pathophysiology, and treatment of dystonia in SCA remain incompletely understood.

This review aims to summarize the current literature on dystonia in SCAs, outlining its prevalence, clinical presentations, underlying mechanisms, and therapeutic strategies.

The authors conducted a systematic literature review in PubMed (up to October 2025) with various search terms related to dystonia and spinocerebellar ataxia, including specific SCA types. Full text articles were included in the review based on clinical relevance.

Dystonia has been observed in the common SCAs such as SCA1, 2, and 3, as well as several of the rarer SCA types. While focal dystonias such as cervical dystonia and task-specific dystonia (writer's cramp) are frequent manifestations, generalized dystonias are also documented. Dystonia may follow the ataxia, or can be the presenting symptom itself. Dystonia in SCA results from dysfunction in the interconnected brain networks primarily involving the cerebellum, basal ganglia, thalamus, and sensorimotor cortex. An altered dopaminergic signalling may be present as well. Treatment responses to levodopa, anticholinergics, botulinum toxin, and deep brain stimulation vary widely, underscoring the need for individualized therapeutic approaches.

Recognizing dystonia as a part of the SCA spectrum is important for timely diagnosis and management. Further studies are required to elucidate the mechanisms and explore the targeted interventions.