The choroidal fissure is a well-defined anatomical structure, a natural cleft between the thalamus and the fornix identified by following the choroid plexus in the lateral ventricle. It originates at the inferior choroidal point behind the head of the hippocampus and constitutes the medial wall of the posterior two-thirds of the temporal horn. The tela chorioidea, which is a double layer of the arachnoid membrane, invaginates through it into the lateral ventricles and forms the choroid plexus. Asymptomatic choroid plexus cysts are a frequent incidental autoptic finding. Most choroid plexus cysts are located in the body and atrial portions of the lateral ventricle. They are usually less than 1.5-2 cm in diameter and do not create clinical signs or symptoms ; however, a choroid plexus cyst located at the level of the temporal horn (choroidal fissure cyst) may produce signs or symptoms of compression. In fact, in this area, the fissure is so shallow that even a small cyst might compress the underlying hippocampus, causing neuronal loss and subsequent glial scarring, which may then become epileptogenic . Most choroidal fissure cysts (CFC) are believed to be benign and asymptomatic and are usually an incidental MRI finding, when the latter is performed to exclude other diagnostic hypotheses. At MRI, CFC usually appear as focal CSF-intensity lesions which dilate the choroidal fissure of the temporal lobe. Therefore, MRI findings of the CSF-like cysts are important to recognize, so that they are not confused with other, more serious entities, such as intra-axial cystic tumours, or infectious or parasitic lesions. We describe two cases, a pediatric and an adult patient, presenting with complex partial seizures associated with CFC at MRI. The signal intensity of the cyst was identical to that of the CSF and the underlying mesial temporal lobe was compressed by the cyst. Since seizures were efectively controlled through drug treatment, surgery was not performed. The temporal lobe and, in particular, the hippocampal and amygdaloid structures have a low epileptogenic threshold : hence, a CFC of sufficient dimensions to compress these structures may be able to determine the onset of temporal epileptic seizures. Sometimes, as in our adult patient, syncope manifestations can be the only clinical sign.
|Issue number||4 SUPPL.|
|Publication status||Published - 2000|
ASJC Scopus subject areas
- Clinical Neurology