Topics

Topic

design image
Choroid fissure

The choroid fissure is a narrow cleft along the medial wall of the lateral ventricles, formed by the apposition of the pallial roof (hippocampal formation) and the tela choroidea. It extends from the foramen of Monro anteriorly to the temporal horn of the lateral ventricle posteriorly. The choroid fissure is the entry site of the choroid plexus into the lateral ventricles, serving as a passage for blood vessels and cerebrospinal fluid (CSF) pathways.

The fissure is bounded laterally by the hippocampal formation and medially by the thalamus and fornix, and it represents a potential site for cerebrospinal fluid collections, choroid plexus cysts, and certain pathologies such as choroid fissure cysts or intraventricular hemorrhage. Its position and integrity are important for neurosurgeons, neuroradiologists, and neurologists for planning interventions and interpreting imaging.

Function

  • Provides a passage for choroid plexus and vessels into the lateral ventricles

  • Contributes to CSF production and circulation

  • Marks a surgical and radiological landmark in ventricular anatomy

  • Helps define medial-lateral ventricular boundaries

  • Associated with pathological potential for cysts or vascular anomalies

Synonyms

  • Choroidal fissure

  • Fissura choroidea

  • Medial ventricular cleft

MRI Appearance

T1-weighted images:

  • Appears as a thin, linear hypointense cleft along the medial wall of the lateral ventricles

  • The choroid plexus protruding into the fissure appears slightly hyperintense relative to CSF

  • Useful for identifying cysts, hemorrhage, or mass lesions along the fissure

T2-weighted images:

  • The fissure itself is low signal along its margins, with surrounding CSF appearing bright (hyperintense)

  • The choroid plexus within the fissure shows intermediate signal

  • Ideal for detecting CSF collections, cysts, or edema adjacent to the fissure

STIR (Short Tau Inversion Recovery):

  • Normal fissure margins remain low signal

  • Pathological fluid, edema, or cystic lesions appear hyperintense, highlighting abnormal collections

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal choroid plexus within the fissure shows mild homogeneous enhancement

  • Pathological lesions (e.g., tumors, vascular malformations) demonstrate enhancement along fissure margins or within the plexus

CT Appearance:

  • Appears as a thin hypodense cleft along the medial wall of the lateral ventricles

  • Choroid plexus is hyperdense relative to CSF, protruding into the fissure

  • CT is useful for detecting intraventricular hemorrhage, calcifications, cysts, or mass lesions

  • Axial and coronal reconstructions clearly delineate fissure location and its relation to adjacent brain structures

MRI images

Choroid fissure axial mri image