Fixational eye movements in Tourette syndrome

• Published in: Neurological sciences 2017-11, Vol.38 (11), p.1977-1984
• Main Authors: Shaikh, Aasef G., Finkelstein, Shlomit Ritz, Schuchard, Ronald, Ross, Glen, Juncos, Jorge L.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Anxiety Disorders - complications; Anxiety Disorders - drug therapy; Anxiety Disorders - physiopathology; Attention Deficit Disorder with Hyperactivity - complications; Attention Deficit Disorder with Hyperactivity - drug therapy; Attention Deficit Disorder with Hyperactivity - physiopathology; Basal ganglia; Biomarkers; Comorbidity; Eye Movement Measurements; Eye movements; Female; Fixation, Ocular - physiology; Gilles de la Tourette syndrome; Humans; Male; Medicine; Medicine & Public Health; Middle Aged; Neostriatum; Neurology; Neuroradiology; Neurosciences; Neurosurgery; Obsessive-Compulsive Disorder - complications; Obsessive-Compulsive Disorder - drug therapy; Obsessive-Compulsive Disorder - physiopathology; Original Article; Psychiatry; Receptive field; Saccades - physiology; Saccadic eye movements; Severity of Illness Index; Superior colliculus; Thalamus; Time Factors; Tourette syndrome; Tourette Syndrome - complications; Tourette Syndrome - drug therapy; Tourette Syndrome - physiopathology; Young Adult
• ISSN: 1590-1874; 1590-3478
• DOI: 10.1007/s10072-017-3069-4

Studies of saccadic eye movements in subjects with Tourette syndrome (TS) have provided additional evidence that there is a link between TS symptoms and deficits in fronto-striato-thalamic networks. These studies revealed impaired timing and inhibition of saccades. We compared fixational eye movements, such as microsaccades and ocular drifts , in subjects with TS and healthy controls.We measured horizontal and vertical eye positions with video-oculography in 14 subjects with Tourette syndrome. We found reduced microsaccade amplitude but increased time between adjacent microsaccades (intersaccadic interval). Hence, the rate of microsaccades was reduced in subjects with TS compared to controls. Measure of ocular stability during intersaccadic intervals revealed increased drift velocity and increased variance in eye position. We hypothesize that increased activity of the direct fronto-striatal pathway and the resulting reduction in basal ganglia outflow targeting the superior colliculus fixation zone affect the rate and amplitude of microsaccades in subjects with TS. The resulting impairment in frontal eye field fixation leads to increased drifts during intersaccadic interval in subjects with TS. Possible clinical implication for these results is that fixational eye movements can be objective biological markers of TS.