What is the recommended imaging study for a patient presenting with symptoms of a herniated disc on the left side of the body?

Imaging for Herniated Disc with Left-Sided Symptoms

MRI without contrast of the affected spinal region is the recommended first-line imaging study for patients with suspected disc herniation presenting with radicular symptoms on the left side of the body. 1, 2

Imaging Selection Algorithm

Initial Assessment

• For patients with suspected disc herniation and radicular symptoms:
  • MRI without contrast is the preferred initial imaging modality when neurological symptoms are present 1, 2
  • MRI offers superior visualization of soft tissue structures including herniated discs, nerve root compression, and spinal cord involvement 1
  • Target the MRI to the specific area of suspected pathology (cervical, thoracic, or lumbar) based on clinical presentation 2

When to Use MRI

• MRI is indicated when:
  • Radicular symptoms (pain, numbness, weakness) are present
  • Symptoms persist beyond 6 weeks of conservative management
  • Neurological deficits are present
  • "Red flags" exist (progressive neurological deficits, cauda equina symptoms, history of cancer, unexplained weight loss, fever) 2

When to Consider Other Imaging

• Plain radiographs:

  • May be used as initial screening for structural abnormalities but have limited value for disc herniation 1, 2
  • Not recommended as the sole imaging modality for suspected disc herniation

• CT scan:

  • Consider when MRI is contraindicated (pacemaker, metal implants, claustrophobia)
  • Superior for bony detail but less sensitive for nerve root compression compared to MRI 1
  • Less effective than MRI for detecting disc herniation 3

• CT myelography:

  • Reserved for cases where MRI is contraindicated or results are equivocal
  • Invasive procedure with potential complications 1

Clinical Considerations

Diagnostic Accuracy

• MRI has superior sensitivity (91.7%) and specificity (100%) compared to CT (83.3% sensitivity, 71.4% specificity) for lumbar disc herniation 3
• MRI excels at displaying cord compression caused by disc herniation, bone fragments, and hematomas 1
• False-positive rates for cervical spine MRI range from 25% to 40%, emphasizing the importance of correlating imaging findings with clinical presentation 1

Important Caveats

• MRI findings must be interpreted in conjunction with clinical symptoms, as asymptomatic disc abnormalities are common 1
• MRI alone should not be used to diagnose symptomatic cervical radiculopathy and should always be interpreted in combination with clinical findings 1
• Contrast-enhanced MRI is generally not necessary for initial evaluation of disc herniation unless infection, inflammation, or neoplasm is suspected 2
• Avoid unnecessary imaging in the first 6 weeks of symptoms unless red flags are present 2

Special Situations

• For suspected thoracic disc herniation (which can present with lower extremity symptoms), targeted thoracic spine MRI should be considered, especially when lumbar imaging is negative 4
• In cases of suspected cauda equina syndrome, urgent MRI without contrast is the preferred imaging modality 2

By following this evidence-based approach to imaging selection, clinicians can accurately diagnose disc herniation while avoiding unnecessary tests, leading to appropriate treatment decisions and improved patient outcomes.