Posterior Reversible Encephalopathy Syndrome (PRES) in an Elderly Patient With Advanced Parkinson's Disease and Autonomic Dysfunction: A Case Report and Literature Review.

Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiological syndrome characterized by neurological disorder and distinctive neuroimaging findings of vasogenic edema, most commonly involving the parieto-occipital regions. Blood pressure fluctuation is a common complaint in patients with Parkinson's disease (PD), which might be explained by autonomic nervous system dysfunction, which impairs the body's ability to automatically regulate blood pressure. Additionally, PD medications can sometimes contribute to these fluctuations, leading to episodes of both low and, less commonly, high blood pressure. We report a case of an 82-year-old female patient with a longstanding history of PD who presented with symptoms of decreased level of consciousness and was found to have typical magnetic resonance imaging (MRI) characteristics of PRES. The patient had a history of blood pressure fluctuations with diurnal variation, which is a recognized autonomic dysfunction in PD. This case underscores the possible association between autonomic dysfunction in PD and the development of PRES. With appropriate blood pressure control, the patient showed both clinical and radiological improvement. This report also reviews the literature on PRES in elderly patients, autonomic dysfunction in PD, and the management considerations in such complex cases.