Lumbar Free Discal Fragment Migrated Posteriorly the Dural Sac

Abstract

We report a case of a lumbar free discal fragment migrated posteriorly to the dural sac. The patient was studied by CT and MR with contrast; then the surgical specimen was evaluated histopathologically to correlate MR imaging before and after contrast with the histological findings.

A free discal fragment is a fibrous and fibrochondroid intracannular mass detached from an intervertebral disc, and completely separated from it. The discal fragment may be located adjacent to the parent disc, but in other cases, the fragment can migrate far from the disc; exceptionally it can migrate behind the dural sac.

Preoperative neuroradiological assessment first of all requires definite identification of the nature of the lesion, distinguishing the fragment from other intracanal masses that may have similar features.

Some authors claim that in general the clinical symptoms caused by a free fragment are more severe than those produced by a contained herniated disc, so that the patient undergoes diagnostic examination earlier on, when the herniated fragment is not yet dehydrated.

In conclusion, it is important to establish the MR characteristics of free discal fragments to avoid confusing this condition with other intracanal lesions.