Dystonic Tremor and Spasmodic Dysphonia in Spinocerebellar Ataxia Type 12.

Abstract

Autosomal dominant inherited spinocerebellar ataxias (SCAs) comprise a group of heterogeneous disorders. Although progressive ataxia resulting from cerebellar degeneration is the hallmark of these disorders and usually the first manifesting symptom, additional features further complicate clinical presentation and may even precede ataxia onset. Their recognition allows the delineation of precise phenotypic-genotypic correlations, which may facilitate prompt and accurate diagnosis. In this regard, the presence of prominent action tremor of the arms and head tremor has been predominantly associated with SCA12, a rare SCA resulting from CAG repeat expansions in the PPP2R2B gene, which is more prevalent in the Indian population. Additional symptoms include pyramidal tract involvement, parkinsonism, and late psychiatric features. Although dystonia has been noted in SCA12 (laterocollis, foot dystonia, and “axial dystonia”), predominant craniocervical and laryngeal involvement have not been previously recognized. Here, we present a 39-year-old female with tremulous dystonia of the face, neck, and arms, spasmodic dysphonia, and subsequent ataxia diagnosed with SCA12. Thus, SCA12 should be considered in the differential diagnosis of tremor, including dystonic tremor.