August 4, 2016
A 33-year-old man with a 10-month history of left sciatic pain (S1 distribution)
Intravertebral Disc Cyst
- Background:
- Discal cysts are a rare entity clinically presenting as a disc herniation. They represent intraspinal extradural cysts in direct contact with the intervertebral disc.
- Etiology is unclear, but possibilities include reabsorption of a previous herniation, hematomas with associated disc prolapse, or mucoid degeneration.
- Relevant Clinical Information:
- Clinical presentation is indistinguishable from disc herniation: low back pain, sciatica, and motor and sensory weakness in the affected nerve root miotome. Bladder or bowel dysfunction have not been reported yet.
- Presentation tends to occur at higher lumbar levels and younger age compared to disc herniations.
- Key Diagnostic Features:
- Round to oval intraspinal cystic mass on MRI. Hypo- or isointense on T1WI and hyperintense on T2WI sequences. In contact with intervertebral disc.
- Minimal degeneration of the disc itself. Most often they arise without a disc herniation, but may arise in this context.
- Differential Diagnoses:
- Tarlov perineural cyst: Located along the nerve root sleeve, not related to the disc, may expand the foramen
- Synovial cyst: Located in the posterolateral epidural space, related to the facet joint, almost invariably associated with facet joint osteoarthritis; may have inflammatory changes associated
- Arachnoid cyst: Long segment lesions, usually located dorsally in the thoracic spine
- Dermoid cyst: Should have fat signal within the lesion
- Treatment:
- Similar to standard intervertebral disc herniation. Initially, a conservative approach is preferred, unless there is a severe neurologic deficit. If there is no clinical response, surgical treatment should be offered with nerve root decompression by cyst removal. Surgical excision also offers the advantage of confirming the diagnosis with a pathologic exam.
- Symptom relief is generally immediate following surgery.
