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33 Year Old Female With Headaches

Cavum Velum Interpositum

Synonyms cavum velum triangulare, cyst of velum interpositum

A cystic dilitation of the cistern of the Velum Interpositum

Imaging Features

Axial images shows triangular shaped CSF space between bodies of lateral ventricles with splaying of the fornices and anterior displacement of the septum pellucidum

Morphology - triangle (apex at foramen of Monroe and base towards the quadrigeminal plate)

Located: - midline between lateral ventricles

- above 3rd ventricle

- contains internal cerebral veins

Imaging Findings

MRI- triangular cavity of CSF between bodies of lateral ventricles.

- sagittal shows cavity to be slit-like to round/ovoid CSF collection below fornices, above the 3rd ventricle

CT- triangular cavity of CSF that does not

extend anterior to foramen of Monroe

and does not enhance.

Differential Diagnosis

Normal cistern of velum interpositum

Cavum Septum Pellucidum, Cavum Vergae

Arachnoid Cyst

Epidermoid Cyst

Pathology

Usually small pial lined CSF space unapparent at autopsy

Etiology

Fetal cerebral hemispheres form and expand with deep midline cleft to form the transverse fissure

Pia infolds along transverse fissure and forms CSF cistern of Velum Interpositum

Cystic dilatation of Velum Interpositum may occur precise etiology unknown

Clinical and Treatment

Usually asymptomatic

Loose association with headache but relationship to cyst unclear

Usually no treatment. Symptomatic lesions have been fenestrated or shunted

Cavum Septi Pellucidi+/- Cavum Vergae CAVUM CORPUS CALLOSUM

Location

CSP- between frontal horns of lateral ventricles

CV- posterior extension between fornices

Pathology

CSP or CV are not the 5th or 6th ventricles misnomer

May or may not communicate with the ventricles