Scientific articles and clinical trials
The diagnostic value of saccades in movement disorder patients: a practical guide and review (Pichet Termsarasab, Thananan Thammongkolchai, Janet C. Rucker, and Steven J. Frucht)
Saccades are rapid eye movements designed to shift the fovea to objects of visual interest. Abnormalities of saccades offer important clues in the diagnosis of a number of movement disorders. In this review, we explore the anatomy of horizontal and vertical saccades, discuss practical aspects of their examination, and review how saccadic abnormalities in hyperkinetic and hypokinetic movement disorders aid in diagnosis, with video demonstration of classic examples. Documentation of the ease of saccade initiation, range of motion and conjugacy of saccades, speed and accuracy of saccades, dynamic saccadic trajectory, and the presence or absence of saccadic intrusions and oscillations are important components of this exam. We also provide a practical algorithm to demonstrate the value of saccades in the differential diagnosis of the movement disorders patient.

Saccades are one of the most useful types of eye movements in the evaluation of the movement disorders patient. The presence of characteristic saccadic abnormalities can be enormously helpful in guiding diagnosis in the outpatient clinic. We present a simplified review the anatomy of horizontal and vertical saccades, discuss practical aspects of their examination, and review saccadic abnormalities in hyperkinetic and hypokinetic movement disorders. Further, we provide an algorithm illustrating the value of saccadic abnormalities in the differential diagnosis of the movement disorders patient. The goal is to provide a practical guide to bedside evaluation of saccades in the context of the movement disorders patient. As such, comprehensive coverage of normal and abnormal ocular motor anatomy and physiology are not included and the reader is referred to comprehensive coverage elsewhere.
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Multiple step pattern as a biomarker in Parkinson disease (Tanya Blekher, Marjorie Weaver, Jason Rupp, William C. Nichols, Siu L. Hui, Jacqueline Gray, Robert D. Yee, Joanne Wojcieszek, and Tatiana Foroud)

To evaluate quantitative measures of saccades as possible biomarkers in early stages of Parkinson disease (PD) and in a population at-risk for PD.

The study sample (n = 68) included mildly to moderately affected PD patients, their unaffected siblings, and control individuals. All participants completed a clinical evaluation by a movement disorder neurologist. Genotyping of the G2019S mutation in the LRRK2 gene was performed in the PD patients and their unaffected siblings. A high resolution, video-based eye tracking system was employed to record eye positions during a battery of visually guided, anti-saccadic (AS), and two memory-guided (MG) tasks. Saccade measures (latency, velocity, gain, error rate, and multiple step pattern) were quantified.

PD patients and a subgroup of their unaffected siblings had an abnormally high incidence of multiple step patterns (MSP) and reduced gain of saccades as compared with controls. The abnormalities were most pronounced in the more challenging version of the MG task. For this task, the MSP measure demonstrated good sensitivity (87%) and excellent specificity (96%) in the ability to discriminate PD patients from controls. PD patients and their siblings also made more errors in the AS task.

Abnormalities in eye movement measures appear to be sensitive and specific measures in PD patients as well as a subset of those at-risk for PD. The inclusion of quantitative laboratory testing of saccadic movements may increase the sensitivity of the neurological examination to identify individuals who are at greater risk for PD.
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Saccadic Eye Movements During a Prognosis Activity in Patients with Early Stages of Parkinson's Disease. (Baziyan Boris, Bez Larisa, ChigaleiIchik Larisa, Damyanovich Elena, Ryabchikova Natalia)
Parkinson's disease (PD) is a slowly grow progressively neurodegenerative disease of The nervous system. It manifests tremor, hypokinesias, muscular rigidity, postural instability. In most cases, patients with PD have violations of cognitive functions. The process of prognosis the appearance of the events is one of the cognitive brain functions underlying of the human intellectual activity. Numerous studies have shown that cognitive processes (attention, memory, thinking) accompanied by saccadic eye movements. Moreover, the cognitive processes are often complicated without those movements. Functional and anatomical overlapping of brain structures (frontal and parietal cortex areas, basal ganglia) provides, on the one hand, the process of planning, programming and decision making, on the other - the control of saccades generation.
Cognitive functions are closely linked with saccadic eye movements. Early, we assumed the saccades are needed to "glue" the "cognitive fragments" into a single idea, leading to a decision-making, to receive, process and store information in the memory during the interval between saccades [2]. Parallel impaired of motor and cognitive functions in Parkinson's disease is found to be changed. The oculomotor system is highly sensitive to functional brain changes and therefore the saccadic movement's disorders can be observed in the early Parkinson's disease stages. In view of above, the aim of the present study is to investigate the possible parallel changes in the cognitive and oculomotor systems in the early stages of Parkinson's disease.
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Identification of persons in the latent stage of Parkinson's disease: the first results of the Russian observational study PARKINLAR (E. Fedotova, A. Chechetkin, N. Abramycheva, L. Chigaleychik, B. Baziyan, T. Ponomareva, N. Alekseeva, P. Fedin, M. Kravchenko, S. Illarioshkin)
Nowadays it is firmly established that Parkinson's disease (PD) is characterized by a long, many years of latent stage, during which the increasing death of neurons is not yet accompanied by the appearance of distinct motor symptoms. For a long time, the neurodegenerative process is manifested by a combination of premotor symptoms - sensory (loss of smell, violation of color vision, pain syndrome), vegetative (constipation, erectile dysfunction, sympathetic denervation of the myocardium, etc.), neuropsychological (conduct disorder in the phase of sleep with rapid eye movements, depression, etc.). These symptoms can occur for 15-25 years before the manifestation of the typical movement disorders, and conversion in the premotor phase motor marks the death is not less than 60% of nigral neutrons. It is obvious that the possibility of neuroprotection is maximized in the latent stage of PD. For effective use of the existing long-term "therapeutic window" is required to develop reliable biomarkers lifetime latent stage PD - neuroimaging, neurophysiology, molecular pathochemical.
Eye movements could help in diagnosis of neurological disorders
In a study published on Aug. 30 in the Journal of Neurology, researchers claim that because Attention Deficit Hyperactivity Disorder (ADHD), Fetal Alcohol Spectrum Disorder (FASD) and Parkinson's Disease each involve ocular control and attention dysfunctions, they can be easily identified through an evaluation of how patients move their eyes while they watch television.

"Natural attention and eye movement behavior — like a drop of saliva — contains a biometric signature of an individual and her/his state of brain function or dysfunction," the article states. "Such individual signatures, and especially potential biomarkers of particular neurological disorders which they may contain, however, have not yet been successfully decoded."
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Possible Neurophysiological Markers of Early Neurodegenerative Process: Parkinson's Disease (B. Kh. Baziyan)

We used tests for evaluation of latent period, duration, and accuracy of eyes, head, or hand movements and their coordinated movements. Comparative analysis of these parameters was performed in healthy subjects and in patients with early stages of Parkinson's disease. The pathology data significantly (p<0.05) differed from those in normal control subjects. These results can be used as neurophysiological markers of early neurodegenerative process. Increasing the number of tests would lead to better specificity of the markers. It will be possible to create a battery of neurophysiological tests most likely reflecting the predictive basis of early neurodegenerative process.
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