Presentation
Headache and nausea
Patient Data
A large cystic lesion is present, occupying and expanding the third ventricle, leading to obstruction of the foramina of Monro, which has resulted in obstructive hydrocephalus. This is evidenced by the enlargement of the temporal horns of the lateral ventricles and the presence of transependymal edema. The cyst contains fluid with signal characteristics distinct from cerebrospinal fluid (CSF): hyperintense on T1, hypointense on T2 compared to CSF, and hyperintense on FLAIR sequences. There is minimal enhancement of the cyst wall without nodules or septations, findings that are suggestive of a colloid cyst of the third ventricle.
Additionally, there is a right deep frontotemporal arteriovenous malformation (AVM) with a moderate nidus in the mesial temporal lobe. The AVM is probably supplied by branches of the right posterior cerebral artery (P2 segment). There is a venous varicosity as it drains into basal vein of Rosenthal and subsequently into the vein of Galen. There is no significant mass effect or associated hemorrhage noted.
Case Discussion
This case presents a compelling example of two distinct yet significant intracranial conditions: a colloid cyst of the third ventricle and a deep frontotemporal arteriovenous malformation (AVM). The colloid cyst, which is benign but strategically located at the foramen of Monro, has led to obstructive hydrocephalus, a known but infrequent complication. The imaging features, including its hyperintensity on T1 and hypointensity on T2, align with typical presentations of colloid cysts, underscoring the importance of early detection to prevent acute hydrocephalus.
On the other hand, the AVM in this case illustrates the complex vascular architecture typical of such malformations, with a nidus and multiple feeding arteries. This needs to be assessed with catheter angiography to confirm the supply and drainage pattern. Although AVMs are generally congenital, they can evolve over time, posing risks of hemorrhage or seizures. In this case, the absence of hemorrhage or significant mass effect is notable, as these factors significantly influence both prognosis and treatment strategies.
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