Posterior reversible encephalopathy syndrome

Case contributed by Alessandro Spano Mello
Diagnosis certain


Female patient with HIV/AIDS, chronic diarrhea, acute pancreatitis, seizures and visual changes. Normal blood pressure levels.

Patient Data

Age: 30 years
Gender: Female

MRI at the onset of symptoms.


T2 and FLAIR hyperintense signal at white matter with vasogenic edema pattern in both occipital and parietal lobes and also in the left frontal lobe. No enhancement after contrast administration.

30 days later


The follow-up images after improvement in clinical status show complete resolution of changes. 

Case Discussion

Posterior reversible encephalopathy syndrome (PRES), is a neurotoxic state with characteristic changes at MRI and CT. Recognized in various conditions like eclampsia, BMT, organs transplant, autoimmune disease, arterial blood hypertension, infection, and sepsis.

The symptoms can be acute and subacute and include headaches, visual changes, paresthesia, hemianopsia, nausea and altered mental status. 

Hypertension is not present or not reach the upper limits of self-regulation (150-160 mmHg) in 25% of patients.

The PRES mechanism remains controversial  but there are two main theories:

  1. High blood pressure leads to loss of self-regulation, hyper-perfusion with endothelial damage and vasogenic edema.
  2. Endothelial dysfunction leads to vasoconstriction and hypo-perfusion resulting in cerebral ischemia and subsequent vasogenic edema.

There are three main imaging patterns:

  1. holohemispheric at watershed zones
  2. superior frontal sulcus
  3. parieto-occipital dominance

Interestingly in our case, the patient had no increase in blood pressure. In fact, she had a myriad of conditions correlated to HIV/ AIDS that probably had resulted in a state toxic/inflammatory that begat PRES.

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