Tuesday 20 September 2011

Interhemispheric cyst without corpus callosal agenesis are usually Arachnoid

A 60 yo female with giddiness since 1 month.
Here is her MRI Brain; Coronal T2, Axial FLAIR, Coronal Post contrast T1, Diffusion and sagittal T1w images.
This MRI study of Brain shows:
A cyst along interhemispheric fissure on left side of falx, in left para sagittal parietal region, isointense to Csf, no restricted diffusion on diffusion. No adjacent parenchymal Gliosis or volume loss. Non enhancing on post contrast T1.
No associated corpus callosal malformation agenesis or dysgenesis on mid sagittal T1. Corpus callosum is compressed.
Cyst is not communicating with ventricular system. Left lateral ventricle compressed.

Imaging wise Possible DDs: Arachnoid cyst, Epithelial cyst.


In an elderly patient inter hemispheric cyst without associated corpus callosal agenesis are usually Arachnoid cysts. Whereas inter hemispheric cyst associated with agenesis of the corpus callosum, which will be clearly demonstrated on magnetic resonance imaging  are usually non arachnoid cysts.
Reference
1. Interhemispheric arachnoid cyst in the elderly: case report and review of the literature; Fumiyuki Yamasaki M.D,
2. A case of symptomatic interhemispheric arachnoid cyst in the elderly by M Tomabechi, K Takano, N Suzuki, G Daita.

Porencephalic cyst ruled out as there is no adjacent parenchymal Gliosis, volume loss or communication with ventricular system.
Epidermoid cyst ruled out as there is no restricted diffusion on diffusion.

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