Dilatation of the Ventriculus Terminalis of the Conus Medullaris MR Findings in Two Patients

Abstract

MR findings in two cases of dilatation of the ventriculus terminalis are described. The ventriculus terminalis is a small lined ependymal cavity that forms during fetal development. It regresses during growth and is not usually visible usually with imaging techniques; it has been described in the past only in pathologic studies. The patients had a history of bilateral polyradiculopathy, bladder and rectal dysfunction and low back pain. MR showed the presence of an ovoidal cystic lesion at the level of the conus medullaris region, with intensity similar to cerebrospinal fluid, without enhancement after i.v. Gd-DTPA. MR is the method of choice to evaluate this abnormality and to obtain a correct differential diagnosis with other benign or malignant pathologies.