From the Guidelines
A disk bulge intending the ventral thecal sac should be initially evaluated with MRI of the lumbar spine, as it provides excellent soft-tissue contrast and accurately depicts lumbar pathology, including disc degeneration, as well as the thecal sac and neural structures 1.
Initial Evaluation
When a disk bulge is suspected to be intending the ventral thecal sac, the primary concern is the potential compression of the spinal nerves and the thecal sac, which can lead to pain, numbness, or weakness in the back or extremities.
- The initial evaluation should focus on identifying the extent of the disk bulge and its impact on the surrounding neural structures.
- MRI is the modality of choice for this evaluation, as it allows for the assessment of the spinal cord, nerve roots, and thecal sac for compression, edema, or abnormal signal 1.
Treatment Approach
The treatment approach for a disk bulge intending the ventral thecal sac typically begins with conservative measures, including:
- Rest for 24-48 hours to reduce inflammation and alleviate pain
- Physical therapy focusing on core strengthening and proper body mechanics to improve spinal stability and reduce pressure on the affected disk
- Anti-inflammatory medications, such as ibuprofen (400-800mg three times daily with food) or naproxen (500mg twice daily), to reduce inflammation and pain
- Muscle relaxants, like cyclobenzaprine (5-10mg three times daily), may be prescribed for associated muscle spasms
Further Evaluation and Specialist Consultation
If symptoms persist beyond 6-8 weeks of conservative treatment, further evaluation with additional imaging or specialist consultation may be necessary to determine the best course of action.
- CT myelography or CT lumbar spine without IV contrast may be useful in assessing the patency of the spinal canal/thecal sac and in preoperative planning 1.
- Specialist consultation with a neurosurgeon or orthopedic surgeon may be necessary to discuss surgical options, such as discectomy or spinal fusion, if conservative treatment fails to alleviate symptoms.
From the Research
Disk Bulge and the Ventral Thecal Sac
- A disk bulge can cause deformities of the margins of the contrast material-filled lumbar thecal sac, but not all such deformities are due to herniated disks 2.
- The deformity caused by a bulging disk is rounded, usually symmetrical, and does not extend above or below the disk space; the nerve root is uniform in caliber and normal in size 2.
- In contrast, the deformity caused by a herniated disk is angular and extends cephalad and/or caudal to the level of the disk space; the affected nerve root is usually widened in its most distal visible part 2.
Diagnosis and Management
- Lumbar disc herniations are common causes of lower back pain, neurological dysfunction, and buttock/leg pain, and diagnosis is achieved with a thorough history and physical examination along with advanced imaging 3.
- Treatment plans are dictated by corresponding patient symptoms and examination findings with their imaging, and most patients can experience relief with nonsurgical measures 3.
- However, if symptoms persist or worsen, surgery may be appropriate, and gabapentin or pregabalin may be used to relieve neuropathic pain after lumbar discectomy 4, 5.
Rare Cases
- Intradural disc herniation is a rare disease that occurs most commonly in the lumbar region, while fewer than 5% occur in the thoracic and cervical regions 6.
- In some cases, the preoperative MRI may not demonstrate an intradural lesion, and it may be identified intraoperatively by inspection and palpation of the thecal sac 6.