Porencephalic cysts - bilateral

Case contributed by Subhan Iqbal
Diagnosis almost certain


Delayed milestones.

Patient Data

Age: 10 years
Gender: Male

Large lobulated cystic structures in the subcortical white matter of bilateral frontoal lobes following CSF signal on all sequences. They communicate with frontal horns of lateral ventricles, with thin rim of cortical mantle around their peripheral aspect. Abnormal hyperintense signals are seen along their periphery, well appreciated on axial FLAIR images. Abnormal hyperintense signals are also seen in the periaqueductal white matter and brainstem. Overall findings are in keeping with bilateral porencephalic cysts, with associated areas of gliosis, which may be sequelae of previous vascular insult.

VP shunt is seen on the right side, the tip of which is lying in the right porencephalic cyst. Temporal horns of bilateral lateral ventricles appear prominent; however, no other sign of hydrocephalus is present. Faint hyperintense signals in bilateral mastoid air cells represent mastoid effusion.

Case Discussion

Porencephalic cysts are an uncommon congenital finding. The cysts are typically lined by white matter. They are thought to occur from focal encephalomalacia due to a localized cerebral insult most frequently during early gestation. Gliosis will develop if the insult is late enough, usually thought to be after the start of the third trimester, although perhaps insults as early as 20 weeks of gestation may result in gliosis.


Additional contributor: Dr Junaid Iqbal

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