This structure originates from vacuolization of undifferentiated aggregated cells called 'caudal cell mass', formed from the fusion of the notocord and neurepithelium, caudally to the posterior neuropore.Progressive coalescence of the vacuoles leads to formation of an ependyma-lined tube that usually fuses with the more rostral central canal.
General physical examination, electrophysiological and urodynamic investigations were all negative, confirming the subjective nature of the patient's symptoms.Lumbar–sacral MRI demonstrated the presence of a cyst lesion containing cerebrospinal fluid (CSF), which did not enhance after gadolinium, compatible with the diagnosis of the terminal ventricle.By extending the MRI investigation to the entire vertebral column and brain, it was possible to exclude an association with other malformations of the central nervous system.A 30-year-old woman was referred to us for recurrent low back pain.The patient was assessed by clinical, electrophysiological (motor evoked potential, somatosensorial evoked potential and electromyography of the perineal and lower limb muscles) and urodynamic investigations as well as a magnetic resonance imaging (MRI) of the lumbar–sacral segment with and without gadolinium enhancement, subsequently extended to the entire vertebral column and brain.Sagittal FSE (a) T1- and (b) T2-weighted images show an oval area with CSF signal intensity with focal expansion of the conus.
The cord parenchyma adjacent to the cavity is thinned Full figure and legend (108K)The sequences obtained after gadolinium administration showed the absence of enhancement of the cyst wall (Figure 3), thus allowing a differential diagnosis with tumoral lesions of the conus medullaris.
From this level, the fusion process progresses at the same time cephalad and caudad.
The craniocephalad and caudad closure, respectively, occur at around 23 and 26 gestation days.
The study was extended to include the entire vertebral column and brain in order to rule out an eventual association with other malformative pathologies of the central nervous system.
Subsequent serial outpatient examinations and MRI of the lumbar–sacral spine, performed 1 and 2 years later, demonstrated the nonevolutive nature of the lesion in terms of both clinical and neuroradiological findings.
Cystic dilatation of the fifth ventricle on its own is an extremely rare pathological event in adults whose pathogenesis is uncertain.