Summary of clinical context: 3 patients with lower back pain were found to have epidural gas pseudocysts using cross sectional imaging. The observation of gas in the epidural space is an important finding as it can be a potentially treatable cause of patient symptoms.
Patient Data: 3 patients, age range 53-75 Sex: 1 female; 2 male Clinical history: All 3 patients presented with lower back pain. Case One had a radiculopathy in the left L5 distibution with associated parasthesia, while Cases Two and Three complained of bilateral leg pain without significant neurology. Plain radiographs demonstrated extensive degenerative disease within the lumbar spine, and an intradiscal vacuum phenomenon was present in all three cases. Cross-sectional imaging revealed the presence of epidural gas pseudocysts. The pseudocyst position in these cases did not correspond to neurological deficit, and surgery was not therefore thought to be appropriate. Case One improved with a local anaesthetic block. Cases Two and Three responded to physiotherapy and simple analgesia.
Discussion: The formation of pockets of nitrogen gas within intervertebral discs is a recognised complication of degenerative spinal disease[1] . Known as the vacuum phenomenon, it can be visualised with plain radiography, MR and CT, and occurs predominantly in the lower lumbar spine. Gas-containing pseudocysts have been observed as spherical bubbles within the epidural space[2-4] . They are associated with disc herniation and a direct connection with the intervertebral discs through an annular tear has been observed[5,6] . Gas chromatograph analysis of the gas aspirated from these pseudocysts has demonstrated nitrogen, thus confirming that they almost certainly originate from the gaseous degeneration of intervertebral discs[7] . The pseudocyst wall has been shown to consist of fibrous material, and their firm non-compressible nature is suggested by their ability to displace nerve roots[1,3] . Gas-containing pseudocysts may present as a spinal mass causing pain and radiculopathy. However, whilst they may be asymptomatic, there is a range of severity reported through to complete nerve palsies[8,9] and cauda equina syndrome[10] .When epidural gas is demonstrated it may be intradural or extradural. Epidural gas is also associated with far lateral disc extrusions and, in up to 2%, intradural disc extrusions[10-12] . These findings are relevant to management planning. The management options depend upon the clinical context and range from observation, injection of steroids, aspiration (percutaneous or surgical)[15-16] through to surgical options including laminectomy or pseudocyst excision.[13-14]
Final diagnosis: Epidural gas pseudocyst.
1. From the provided CT axial images, a localized radiolucent area (gas density) is observed within the spinal canal. The radiolucent area appears round or lobulated and is located in the epidural space, partly adjacent to the intervertebral disc region.
2. Possible degenerative changes are noted in the lower lumbar intervertebral discs, and some discs display a “vacuum sign” (i.e., visible gas within the disc).
3. In some images, the dural sac or nerve roots appear to be subjected to mild to moderate compression or displacement. However, whether there is a clear protrusion of the nerve root needs to be assessed in conjunction with clinical symptoms and other imaging sequences.
4. On the MRI sagittal view, the degenerated disc shows decreased signal intensity. A significantly reduced or missing signal area is observed in the epidural space, corresponding to the gas visibility.
Based on the images and clinical manifestations (back pain, low back and leg pain, etc.), the possible diagnoses include:
1. Epidural Gas Pseudocyst: Usually associated with a disc “vacuum sign” or degeneration. Gas may enter the epidural space through an annular fissure, forming a cyst-like lesion. Imaging features include a localized gas shadow within the spinal canal that may compress the nerve roots.
2. Degenerative Disc Herniation with Gas Formation: In degenerative disc conditions, gas can be produced within the disc. If a herniation is significant, the disc material can further compress the dural sac or nerve roots. In rare cases, the gas can also enter the spinal canal and cause symptoms.
3. Other Gas-Related Cystic Lesions within the Spinal Canal: For example, gas accumulation associated with facet joint or ligamentous cysts. These are generally related to degenerative changes and can present similarly to epidural gas pseudocysts, but are relatively uncommon.
Combining the patient’s age (53 years), clinical symptoms (low back pain), and imaging findings, this case most closely resembles an epidural gas pseudocyst, especially in correlation with degenerative disc “vacuum sign.”
Considering the imaging findings (disc degenerations and epidural gas shadow), clinical symptoms (low back pain, possibly accompanied by radicular pain), and characteristics reported in the literature, the most likely diagnosis in this case is:
“Lumbar Epidural Gas Pseudocyst”, accompanied by degenerative lumbar disc disease.
If confirmation is necessary, additional MRI sequences and, if needed, aspiration or surgical exploration can be considered. Depending on the severity of the patient’s symptoms, nerve conduction studies may also be considered to evaluate any nerve involvement.
1. Conservative Treatment: For patients with mild or intermittent pain, conservative management is recommended initially, including oral or local injections of NSAIDs and analgesics, short-term use of a lumbar support or brace, and bed rest on a firm mattress.
2. Interventional or Surgical Treatment: If the pain is severe, conservative therapy is less effective, or if there is neurological deficit (significant numbness in the lower limbs, motor impairment, etc.), consider the following measures:
- Epidural steroid injection or selective nerve root block to reduce inflammatory response or pain.
- CT- or fluoroscopy-guided percutaneous aspiration of gas from the pseudocyst; some patients may experience relief.
- If the cyst causes significant nerve compression, resulting in severe neurological symptoms or intractable pain, surgical intervention may be performed, such as laminectomy for decompression or cyst excision.
Rehabilitation/Exercise Prescription (FITT-VP Principle):
Disclaimer: This report is generated by an intelligent system based on limited information and imaging provided, and cannot replace a professional in-person diagnosis or treatment recommendation. In case of any questions or worsening symptoms, please seek medical advice from a qualified healthcare professional.
Final diagnosis: Epidural gas pseudocyst.
