Abnormal Eye Movements in Parkinsonism and Movement Disorders

Ileok Jung, Ji-Soo Kim; J Mov Disord. 2019;12(1):1-13. Published online January 30, 2019 DOI: 10.14802/jmd.18034

Friedreich ataxia (FA) is the most common cause of autosomal recessive ataxias with an onset usually before age 20 years. FA is characterized by ataxia, hyporeflexia, extensor plantar reflexes, neuropathy, cardiomyopathy, and diabetes. FA is mostly due to an unstable GAA repeat expansion within intron 1 of frataxin. Abnormal ocular motor findings of FA include fixation instability manifesting as SWJs and ocular flutter . While saccadic velocity is essentially normal, saccadic latency is prolonged. The latency correlates with clinical measures of disease severity. Saccades may be both hypo- and hypermetric. SP and the VOR may be impaired Caloric tests are abnormal in the majority of FA patients. Thus, severe vestibulopathy with essentially normal saccadic velocity are hallmarks of FA and differentiate it from a number of dominant SCA.