Peritrigonal lesion

see Trigone ventricular meningioma

Peri-trigonal lesions pose special neurosurgical challenges for their exposure and resection because of their proximity to critical structures, including the overlying cortices and white matter fiber tracts. The anterior and posterior choroidal, pericallosal, and splenial arteries provide blood flow to the surrounding normal parenchyma as well as to lesions in this area. There is also significant deep venous drainage via the indispensable internal cerebral veins, Basal vein of Rosenthal, and the straight sinus. Highly functional cerebral cortex and white matter tracts in this area include the optic radiations lateral to the ventricle ¹⁾postcentral gyrus supralaterally, and the thalamus anteroinferiorly.

T1-weighted spin-echo/sagittal sequences, FLAIR/transverse, T2-weighted turbo spin-echo/transverse, T2-weighted fast field echo/transverse, T1-weighted spin-echo/transverse, T2-weighted turbo spin-echo/coronal, and transverse, sagittal, and coronal sequences with gadolinium. 3D diffusion study.

In the posterior fossa, the signal intensity of the cerebellar parenchyma and the signal of the pons remain correct and uniform. The fourth ventricle is not dilated. In the sagittal plane, the cerebellar tonsils remain intracranial.

At the left temporo-occipital level, as described in the previous examination, a cystic lesion persists, and its size and characteristics have not changed. After gadolinium administration, no abnormal contrast enhancement is observed. The ventricles appear deformed due to the mass effect of the lesion, but there is no modification in the signal intensity of the parenchyma. The midline is not displaced.

Conclusion: Left occipital cystic lesion without appreciable changes compared to the previous MRI.