Saccadic eye movements in juvenile variant of Huntington disease

Background and purpose: Huntington disease (HD) is a neurodegenerative disease leading to involuntary movements, cognitive and behavior decline. The juvenile variant of HD (JHD) manifests in people younger than 21 and is characterized by a different clinical presentation, i.e. rigidity and bradykinesia. Rapid eye movements were not extensively studied in patients with JHD. Aims of our study were to describe the saccadic eye movements in JHD patients and to find a correlation between the saccade abnormalities, severity of the disease and cognitive and behavior deterioration. Materials and methods: We studied 10 patients with JHD and 10 healthy subjects. Reflexive and volitional saccades were assessed with the Saccadometer Advanced. The battery of cognitive and behavior tests was performed as well. Results: We found a prolonged latency, slowness and decreased velocity of reflexive and voluntary saccades and reduced amplitude of voluntary saccades. Moreover, patients with JHD executed a significantly lower number of volitional saccades and made more incorrect cued saccades than controls. We noted a significant correlation between prolonged latency of reflexive saccades with gap task and disease severity and significant inverse correlation between prolonged latency of reflexive saccades with overlap task, an increased number of incorrect saccades made on a cue and impairment in working memory. Conclusion: Abnormalities of saccade eye movements in patients with JHD were similar to those reported in patients with HD. Our findings did not confirm abnormalities previously reported in patients with early onset HD. Abnormal saccade parameters correlated also with a disease severity and cognitive deterioration.