What are the characteristic features and imaging findings of posterior reversible encephalopathy syndrome (PRES)?

What are the characteristic features and imaging findings of posterior reversible encephalopathy syndrome (PRES)?

• A. MRI shows asymmetrical focal gray matter enhancement.
• B. MRI shows symmetric vasogenic edema in posterior regions, often parieto-occipital; clinical features include headache, seizures, visual disturbance, hypertension.
• C. CSF analysis shows pleocytosis with fever.
• D. CT shows diffuse cortical atrophy.

Answer: (B)

PRES is defined by disruption of cerebral autoregulation that leads to vasogenic edema, most often in the posterior circulation. Clinically, patients frequently present with headache, seizures, visual disturbances, and hypertension, especially in acute or severe cases. On imaging, MRI is characteristic: symmetric edema in the posterior regions of the brain, classically the parieto-occipital white matter, seen as hyperintense on T2/FLAIR sequences. This edema is vasogenic, so diffusion-weighted imaging typically does not show marked restricted diffusion (unlike cytotoxic edema). Importantly, this process is usually reversible with timely blood pressure control and addressing any triggering factor. The other options don’t fit PRES: asymmetrical focal gray matter enhancement isn’t typical; CSF findings of pleocytosis with fever suggest infectious or inflammatory meningitis/encephalitis; diffuse cortical atrophy on CT points to chronic degenerative changes rather than acute PRES.

PRES is defined by disruption of cerebral autoregulation that leads to vasogenic edema, most often in the posterior circulation. Clinically, patients frequently present with headache, seizures, visual disturbances, and hypertension, especially in acute or severe cases.

On imaging, MRI is characteristic: symmetric edema in the posterior regions of the brain, classically the parieto-occipital white matter, seen as hyperintense on T2/FLAIR sequences. This edema is vasogenic, so diffusion-weighted imaging typically does not show marked restricted diffusion (unlike cytotoxic edema). Importantly, this process is usually reversible with timely blood pressure control and addressing any triggering factor.

The other options don’t fit PRES: asymmetrical focal gray matter enhancement isn’t typical; CSF findings of pleocytosis with fever suggest infectious or inflammatory meningitis/encephalitis; diffuse cortical atrophy on CT points to chronic degenerative changes rather than acute PRES.