Objective: Our understanding of the psychosis in Parkinson’s disease (PDPsy) is incomplete, and standard of care treatment with antipsychotics has its limitations. Neuroimaging and histopathology in PDPsy reveal that visual hallucinations (VHs), the hallmark of psychosis in PDPsy, arise from the cortical visual association areas, yet little work has been done using electrophysiology. We hypothesize that using electroencephalography (EEG) we will detect cortical excitability in the visual association areas.

Background: PDPsy is one of the most challenging non-motor symptoms to manage. Psychosis in Parkinson’s disease manifests with mainly VH. The prevalence of VH in PD is approximately 40%, and up to three-quarters of people with PD (PwP) are estimated to develop VHs over a twenty-year period. Parkinson’s disease psychosis causes alarm to patients and their caregivers and can result in ER visits. Often, the presence of psychosis in PD leads to limiting the use of dopaminergic medications, which can restrict the treatment of motor symptoms.

Method: In this study, eight randomly selected PwP who experience recurrent VHs underwent a 32-channel ambulatory scalp EEG. Duration ranged from 51 to 943 minutes. Individuals with a prior seizure history were excluded. All individuals described complex VHs on their UM-PDHQ. Description of EEG abnormalities was reported using ACNS Standardized terminology.

Results: Four of eight (50%) individuals had epileptiform activity on EEG: two left parietooccipital, one left anterior temporal, and one right anterior temporal. One patient had VHs while being monitored, but the EEG was uninterpretable at that time.

Conclusion: This study examined the EEG records of eight randomly selected PwP with associated complex VHs. Half had epileptiform activity in the visual association areas, where complex VHs are known to localize. This raises the possibility that cortical hyperexcitability may contribute to a subset of VH in PDPsy. Further studies should be considered on a larger scale and with longer EEG monitoring to capture VH events. This study can be looked at as a starting point for broader electrophysiological studies to better characterize the relationship between VH and EEG abnormalities in PDPsy, which may have therapeutic and diagnostic value.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/electrophysiological-evaluation-of-visual-hallucination-in-parkinsons-disease-psychosis/