[Study of oculomotor disorders in spinocerebellar ataxia genotype]

Spinocerebellar degeneration (SCD) exhibits a variety of spinal and cerebullar symptoms and progress. The recent advent of molecular genetics has revealed triplet repeat mutation in the gene of SCD patients. Due to the underlying genetic defects, hereditary SCD is referred to as different spinocerebellar ataxia (SCA) genotypes. We conducted vestibular functional tests in 33 SCD patients, including 3 with SCA3 and 2 with SCA6. We compared the degree of lower extremity ataxia with the degree of oculomotor disorder by using eye tracking tests (ETT) and optokinetic pattern tests (OKP). Both SCA3 and SCA6 show high ETT score and low mean slowest phase velocity in OKP. This means that SCA3 and SCA6 tend to have oculomotor disorder precedes extremity ataxia. Oculomotor examination should thus prove to be a useful, senstive indicator in screening SCD patients from early disease onset, and in evaluating the disease progression and the effectiveness of treatment.