Abstract Introduction Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state commonly associated with acute hypertension, renal failure, cytotoxic medications, or autoimmune disorders. Normotensive PRES is a rare variant, often under-recognized in clinical settings. We present a unique case of a 57-year-old female with a complex cardiorespiratory history who developed PRES in the absence of hypertension, ultimately attributed to severe hypercapnia. Case Presentation A 57-year-old female with pulmonary hypertension, emphysema, chronic respiratory failure (on 4-6L supplemental oxygen), and heart failure with preserved ejection fraction (HFpEF) presented with acute-onset headache followed by a generalized tonic-clonic seizure, treated with IV benzodiazepines and IV levetiracetam loading dose. Years prior, she had suffered a severe episode of varicella pneumonia complicated by acute respiratory distress syndrome (ARDS), which required prolonged mechanical ventilation and tracheostomy placement. On arrival, she was normotensive, with stable hemodynamics and elevated PaCO2 on arterial blood gas analysis. Neurologic examination revealed postictal confusion and visual field deficits without other focal findings. Brain MRI demonstrated bilateral symmetric hyperintensities in the parieto-occipital regions on FLAIR sequences, consistent with PRES. Lumbar puncture was unremarkable, with no evidence of infection or inflammatory process. Discussion This case illustrates a rare instance of normotensive PRES, likely precipitated by severe hypercapnia. While hypertension remains the most common etiologic factor in PRES, elevated CO2 levels can lead to cerebrovascular dysregulation, endothelial dysfunction, and cerebral vasodilation—mechanisms that may contribute to PRES independent of blood pressure elevation. The absence of hypertension and the presence of chronic cardiorespiratory disease complicated the diagnostic process, emphasizing the importance of considering alternative triggers in atypical presentations of PRES. Conclusion This case highlights the importance of maintaining a broad differential in patients presenting with seizure and encephalopathy, especially those with chronic hypercapnic respiratory failure. Normotensive PRES, though rare, should be considered in the appropriate clinical context, particularly when imaging findings are characteristic, and other etiologies are excluded. This abstract is funded by: None
Rymerson et al. (Fri,) studied this question.