What imaging modalities are recommended for a patient with suspected post-laminectomy syndrome (PLS)?

Imaging for Post-Laminectomy Syndrome

MRI lumbar spine without and with IV contrast is the recommended initial imaging study for patients with suspected post-laminectomy syndrome, as it accurately distinguishes recurrent or residual disc herniations from postoperative scarring and can evaluate for nerve root compression or arachnoiditis. 1

Initial Imaging Approach

• MRI with contrast is superior for evaluating patients with persistent symptoms after lumbar surgery as it can differentiate between scar tissue and recurrent disc herniation 1, 2
• Contrast-enhanced MRI helps identify potential infection, which may be a cause of persistent pain after laminectomy 1
• Early postoperative MRI (even within 6 weeks of surgery) can accurately detect neural compression in patients with continued or worsening symptoms 3

When to Consider Alternative Imaging

• CT lumbar spine without IV contrast should be considered when:

  • Assessing osseous fusion and hardware failure 1
  • Predicting significant spinal stenosis and excluding cauda equina impingement 4, 1
  • When MRI is contraindicated due to implanted non-MRI compatible devices 1

• CT myelography is recommended when:

  • Significant artifact from metallic surgical hardware limits MRI evaluation 1
  • Patients have implanted medical devices that are not MRI safe/conditional 1
  • Detailed assessment of neural foramina and subarticular recesses is needed 4

• Plain radiographs (especially flexion-extension views) are helpful as complementary studies to:

  • Evaluate alignment and hardware integrity 1
  • Provide functional information about abnormal motion/increased dynamic mobility 1

Common Pathologies Detected on Imaging

• Recurrent or residual disc herniation 1, 2, 5
• Postoperative epidural scarring/fibrosis 1, 2, 5
• Hardware failure or pseudarthrosis 1
• Adjacent segment degeneration 1
• Arachnoiditis 1, 2, 6
• Postoperative infection or discitis 1, 5
• Pseudo-meningocele 5

Clinical Considerations

• MRI can determine clinically important functional instability when CT and conventional radiography are inconclusive, particularly helpful in evaluating patients with multiple lumbar surgeries 2
• Documentation of specific signs and symptoms, including radicular pain patterns and neurological deficits is essential for determining appropriate management 1
• MRI findings strongly influence management decisions - studies show that 79% of patients with scans suggesting neural compression had revision surgery 3

Imaging Algorithm for Post-Laminectomy Syndrome

1. Obtain MRI lumbar spine without and with IV contrast as the initial imaging study 1
2. If MRI is contraindicated or limited by hardware artifact, proceed with CT myelography 1
3. Obtain complementary plain radiographs (including flexion-extension views) to assess alignment and hardware integrity 1
4. For patients with suspected cauda equina syndrome, urgent MRI without and with IV contrast is indicated 4

Common Pitfalls to Avoid

• Relying solely on CT for evaluation of soft tissue pathology, as MRI provides superior contrast for evaluating nerve root compression 7
• Performing "exploratory" surgery without definitive objective findings to substantiate the patient's symptoms 6
• Failure to correlate imaging findings with specific clinical symptoms, as anatomical abnormalities may not always be the source of pain 1
• Overlooking the possibility of adjacent segment degeneration as a cause of persistent pain 1