Extracerebellar Signs and Symptoms in 117 Korean Patients with Early-Stage Spinocerebellar Ataxia

BACKGROUND AND PURPOSE: Spinocerebellar ataxias (SCAs) are the most common form of hereditary ataxias. Extracerebellar signs have been well described and are helpful in differentiating the SCA subtypes. However, there are few reports on the early-stage extracerebellar signs in various SCA subtypes. This study explored the clinical and magnetic resonance imaging (MRI) characteristics of early-stage SCAs in the Korean population. METHODS: We retrospectively reviewed the medical records of genetically confirmed SCA patients with a disease duration of <5 years. Data on baseline characteristics, extracerebellar signs, and initial MRI findings were organized based on SCA subtypes. RESULTS: This study included 117 SCA patients with a median age at onset of 40.6 years. The family history was positive in 71.8% of the patients, and the median disease duration and the score on the Scale for the Assessment and Rating of Ataxia at the initial visit were 2.6 years and 5.0, respectively. SCA3 was the most prevalent subtype, and oculomotor abnormalities were the most frequent extracerebellar signs in early-stage SCAs. Saccadic slowing was characteristic of SCA2 and SCA7, and gaze-evoked nystagmus was prominent in SCA6. Parkinsonism was relatively frequent in SCA8 and SCA3. Decreased visual acuity was specific for SCA7. Dementia was not an early manifestation of SCAs. Brain MRI revealed a pattern of pontocerebellar atrophy in SCA2 and SCA7, while SCA6 demonstrated only cerebellar cortical atrophy. CONCLUSIONS: SCA patients exhibited diverse extracerebellar signs even in the early stage. Specific extracerebellar signs were characteristic of specific subtypes, which could facilitate differential diagnoses of early-stage SCAs.