Objective: To describe a spinocerebellar ataxia (SCA) presenting with progressive apraxia of speech (AOS), a previously undescribed SCA phenotype.

Background: Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant, neurodegenerative disease characterized by cerebellar ataxia, including ataxic dysarthria. Accompanying features include hyporeflexia, parkinsonism, and cognitive dysfunction. There are no reported cases of AOS linked to any of the 40+ subtypes of SCA.

Method: Case report.

Results: A 54-year-old man was evaluated for two years of progressive speech changes in the setting of chronic mild imbalance. His father had amyotrophic lateral sclerosis and three paternal uncles had progressive but uncharacterized neurologic symptoms. As part of an ongoing study on speech and language disorders, he underwent detailed speech and language, neurologic, and neuropsychological assessments, and multimodal neuroimaging studies. Speech evaluation revealed slow speech, syllable segmentation, decreased prosodic variation, and mild strain. Speech alternating and sequential motion rates were slow but regular. A consensus diagnosis of primary progressive AOS-prosodic subtype and possible spastic dysarthria was reached among 3 board-certified speech-language pathologists with extensive experience in motor speech disorders, blinded to other data. Neurologic examination revealed mild ataxia in all extremities and difficulty with tandem gait. MRI showed marked pontine-cerebellar atrophy, and FDG-PET showed mild motor/premotor area and prominent posterior fossa hypometabolism. Genetic testing was positive for repeat expansion of CAG in the ATXN2 gene, consistent with SCA2.

Conclusion: Our case demonstrates that progressive AOS can be a manifestation of SCA2 with neuroimaging supported involvement of premotor areas, classically associated with progressive AOS. The perceptual characteristics that define AOS overlap with those of ataxic dysarthria, and hence it is possible that patients with prior descriptions of speech impairment in SCA2 may have had AOS. Careful characterization of the motor speech disorder has implications for treatment approaches.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/progressive-apraxia-of-speech-as-a-presenting-symptom-of-spinocerebellar-ataxia-type-2/