A 24-year-old woman at 34 weeks of gestation presents with seizures and blood pressure of 180/115 mmHg. MRI brain shows symmetric T2 and FLAIR hyperintensity with swelling in the parieto-occipital subcortical white matter bilaterally, without restricted diffusion. What is the most likely diagnosis?

• A Posterior cerebral artery territorial infarction
• B Progressive multifocal leukoencephalopathy
• C Herpes simplex encephalitis
• D Posterior reversible encephalopathy syndrome ✓

Explanation

Posterior reversible encephalopathy syndrome (PRES) is caused by failed autoregulation with vasogenic edema, classically in the parieto-occipital white matter, in settings such as eclampsia, severe hypertension and cyclosporine toxicity. The absence of restricted diffusion distinguishes it from infarction, which is the key discriminator against option A. Herpes simplex encephalitis preferentially involves the medial temporal lobes and cingulate gyri, not the parieto-occipital region.

Reference: Osborn's Brain, 2nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.