The relationship of visual hallucinations and visualeviled potential studies in parkinson's disease

Purpose: Visual hallucinations (GH) have been reported quite frequently during the course of Parkinson's Disease. There are also publications reporting that this condition is associated with disease progression and a higher mortality rate. Given that the pathophysiology of GHs in Parkinson's Disease remains unclear, it is also difficult to treat and poorly effective. In this study, it was aimed to investigate the relationship between visual hallucination and visual evoked potential studies (VEP) to determine whether visual pathway dysfunction is one of the causes of visual hallucinations in Parkinson's disease. Methods: Eighty people (26 Parkinson's patients without visual hallucination, 26 Parkinson's patients with visual hallucinations, and 28 healthy individuals) were included in this study. Demographic information about the patients (age, gender, disease duration, disease severity (Hoehn and Yahr stage), UPDRS (On period; 2 hours after the patient receives the first dose in the morning), presence of motor fluctuation, type if any, presence of dyskinesia, type if any, The drugs they used and their durations (L-dopa, dopamine agonside, seleginin, amantadine and anticholinergic use and their duration, if using dopamine agaonist, agonist-levodopa equvalen doses, total levodopa dose were recorded separately), MMSE, Neuropsychiatric test battery, comorbid diseases, Corrected visual acuity, visual field by confuranation method, ophthalmological examination including cataract history, neuroimaging findings (especially the lesion affecting the visual pathways and posterior cortical atrophy were examined and recorded. The patients were questioned in terms of visual hallucinations (presence, type, time of appearance, presence of insight against hallucination). Electrophysiological examinations were performed in the same laboratory and device for each patient, in the on period. It was performed in a certain time period (between 10:00 and 12:00 in the morning) for all patients. Results: There was no statistically significant difference between the results of electrophysiological studies performed in Parkinson's patients and the results of the control group. When demographic findings were compared between patients with and without GH in the patient group, MMSE scores were found to be higher in patients without GH (p=0.003). Factors independently associated with the presence of visual hallucinations in Parkinson's patients, whereas in multiple logistic regression analysis results, low MMSE score (p=0.002), absence of cataract history (p=0.012) and pathological neuroimaging result (p=0.001) were associated with the presence of GH in Parkinson's patients. Conclusion: In our study, we did not find any significant difference between the results of VEP examinations of patients with Parkinson's Disease who have visual hallucinations, and those who do not have visual hallucinations and healthy individuals. VEP changes in Parkinson's disease represent secondary dopaminergic and/or nondopaminergic thus more chronic changes in visual processing. We think that further studies with larger sample groups are needed in different stages of the disease to reveal additional pathologies beyond the retina, including VEP, and to investigate the relationship between these findings and clinical symptoms, and we think that the data of our study will guide further studies. Keywords: Parkinson's Disease, visual evoked potentials, visual hallucinations