Headache and fixed dilated pupils.
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Figure 1. Sagittal image (A) demonstrates a homogenous isointense mass in the atrium of the right lateral ventricle. The mass remains isointense on both T2 (B) and FLAIR (C). No restricted diffusion on the DWI (D) or corresponding ADC map (E). The mass demonstrates homogenous enhancement on the post contrast T1 image (F). Significant regional mass effect with compression of the ipsilateral midbrain and dilatation of both lateral ventricles consistent with obstructive hydrocephalus.
Figure 2. Post-contrast T1 image demonstrating homogenous enhancement of the mass.
Figure 3. FLAIR images demonstrate uncal compression of the ipsilateral midbrain, in particular, the tectum. Red arrows point to bilateral high signal intensity in the tegmental tracts extending to the level of the pons. Imaging appearance is most consistent with tegmental tract edema and early stages of Wallerian degeneration from midbrain compression.
Differential consideration for intraventricular mass can often be narrowed by age and location of the lesion. Intraventricular meningioma typically occurs in adults and in the atrium of the lateral ventricle more commonly on the left. MR signals are often isointense to brain parenchyma with homogenous enhencement pattern. Rarely meningioma demonstrate restricted diffusion which reflect hypercellularity of the tumor. Intraventricular meningioma have a tendency to reach large size before presentation. Complication include obstructive hydrocephalus and regional mass effect with ipsilateral midbrain compression and uncal herniation. A diligent radiologist will always assess the fiber tracts below the level of compression or lesion to look for signs of tract edema or Wallerian degeneration which can otherwise be overlooked.