Cystic dilatation of ventriculus terminalis in adults: MRI

Abstract

We report the MRI findings in two patients with cystic dilatation of the ventriculus terminalis. The latter is usually a tiny ependyma-lined cavity of the conus medullaris. In both cases the markedly dilated ventriculus terminalis was seen as a rounded cavity with regular margins, the content of which gave the same signal as cerebrospinal fluid with all MR pulse sequences. No contrast enhancement was seen.

Fifth ventricle: an unusual cystic lesion of the conus medullaris

“…Moreover, MRI makes it possible to identify the isolated forms of the fifth ventricle by ruling out any association with other malformative lesions. 1,5,6,9,10,13 An analysis of the data shows that cystic dilatation of the fifth ventricle has two possible types of clinical evolution: in the first, there is a mild clinical onset characterized by a few, nonspecific symptoms and longterm stability of both clinical and radiological parameters, as in our case; alternatively, there may be an evolution of symptoms presumably due to an increase in the size of the cystic lesion inside the conus medullaris. 2 Once a diagnosis of fifth ventricle has been made, two types of treatment are possible: surgical or conservative.…”

“…[1][2][3][4][5][6][7] The process of neurulation, which begins at 3 weeks of embryonic age, leads to the formation of the neural tube by a progressive fusion of the lateral edges of the neural plate starting from the level, of the third and fourth somite. From this level, the fusion process progresses at the same time cephalad and caudad.…”

“…2,5 The fact that the development process of the fifth ventricle is extremely variable means that there may be either a single cavity directly communicating with the central canal of the ependyma (more frequent in pediatric age) or an isolated cystic cavity of the spinal canal. The different morphological entities observed in both adults and children could merely be variants of the normal process of canalization and could therefore be attributed to a continuum of evolution of the conus medullaris.…”

“…Currently, most of the authors [1][2][3][4][5][6][7] believe that isolated cystic dilatation of the fifth ventricle is due to the persistence of this lesion in adulthood and to the abnormal closure of the communication between the ventriculus terminalis and the central canal by ependyma (disembryogentic theory).…”

“…Of the 17 cases described in the literature, 13 presented ingravescent or, at least, invalidating symptoms, 1,[5][6][7][8][9][10][11][12] whereas in the other 4, clinical status remained stable at follow-up. 2,6,13 However, clinical symptoms were entirely nonspecific, even in the cases that evolved, ranging from just low back pain (as in our case) to deficits (lower limb paresis, sphincter dysfunction, etc.).…”