Treatment-induced eye movement response for Parkinson's disease

Parkinson’s disease (PD) is a slowly progressive neurodegenerative disease where the gradual death of dopaminergic cells in the substanta nigra and consequent loss of dopaminergic projections to the striatum disrupts the function of cortico-basal ganglia circuits. This results in motor symptoms such as rigidity, bradykinesia (slowness of movement) and tremor. The pathways affected by PD are also involved in the generation of eye movements. Although oculomotor pathways have been extensively studied, PD treatment-induced changes in their parameters are not well known. There is currently no disease-modifying treatment for PD. Most cases are treated symptomatically with levodopa or Deep Brain Stimulation. One of the factors limiting the rate of development of new treatments, is the reliance on clinical rating scales which are subjective, insensitive and non-linear. Analysing the effect of current treatments on oculomotor response allows characterization of new treatment-assessment tools that is quicker and more sensitive. Previous studies have identified oculomotor parameters as sensitive markers due to their ability for rapid data collection and changes in de-novo PD patients. In addition, treatment-induced changes in gait parameters and manual responses will be used as covariates in analysis to further ensure accuracy. Eye movement, gait and manual responses of PD patients either On or Off medication or stimulation, depending on which treatment they are receiving, are measured along with the usual clinical assessment UPDRS. Objective and quantitative measurements revealed several parameters that are characteristic to each treatment response.