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Gray matter heterotopia and cerebellopontine angle arachnoid cyst

Case contributed by Amro Omar
Diagnosis certain

Presentation

Seizures and developmental delay.

Patient Data

Age: 25 years
Gender: Female

Axial images through the skull base show a cystic lesion just lateral to the left inferior cerebellar peduncle, this cystic lesion has CSF density and no evidence of diffusion restriction. It's suggestive of an arachnoid cyst.

This cystic lesion is exerting mass effect on the left facial and vestibulocochlear nerves before entering the internal auditory canal and on the left glossopharyngeal and vagus nerves before entering the jugular foramen.

The scalp shows a midline lesion in association with suggestive bony defect, through which multiple vessles are seen. This appearance and location suggest a sinus pericranii, further evaluation by contrast-enhanced study is recommended.

Extensive periventricular gray matter nodular heterotopia is seen with indentation in lateral ventricles walls, extensive bilateral heterotopic gray matter are also seen in the frontal subcortical region extending into the frontal horns of the lateral ventricles.

Case Discussion

The grey matter heterotopias are a relatively common group of conditions characterized by interruption of normal neuronal migration from near the ventricle to the cortex, thus resulting in "normal neurons in abnormal locations".

Sinus pericranii is a cranial venous anomaly in which there is an abnormal communication between intracranial dural sinuses and extra-cranial venous structures, usually via an emissary transosseous vein. This case shows findings that suggest this condition, although further study with contrast should be done for confirmation. 

Lateral ventricles dilatation are not associated with other changes related to hydrocephalus, may denoting a poor white matter development.

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