What is the best imaging test to evaluate for spinal cord compression in a patient with severe scoliosis?

Best Imaging Test for Spinal Cord Compression in Severe Scoliosis

MRI of the complete spine without IV contrast is the best imaging test to evaluate for spinal cord compression in a patient with severe scoliosis, as it provides superior soft-tissue characterization, accurately depicts the spinal cord and epidural space, and can identify both the compression and its underlying etiology. 1

Primary Recommendation

• MRI without IV contrast is the gold standard for evaluating spinal cord compression because it excels at depicting soft-tissue pathology, assessing vertebral marrow, and determining spinal canal patency 1
• The complete spine should be imaged (cervical, thoracic, and lumbar regions) since patients with scoliosis have a 2-4% risk of intraspinal abnormalities, and 25% of patients with cord compression have involvement at multiple levels 2, 3
• MRI has a sensitivity of 96% and specificity of 94% for detecting spine pathology with cord compression 1

Why MRI is Superior in Scoliosis Patients

• Severe scoliosis creates unique imaging challenges where the distorted anatomy makes it difficult to assess the spinal cord and canal adequately with other modalities 1
• MRI provides optimal visualization of the intraspinal contents including the epidural space and spinal cord, which is critical when anatomical landmarks are distorted by severe curvature 1
• In scoliosis patients, neural axis abnormalities occur in over 20% of congenital cases and 2-4% of idiopathic cases, making comprehensive cord evaluation essential 2

Specific MRI Protocol for Scoliosis

• Use sagittal STIR (short tau inversion recovery) sequences combined with axial T2-weighted images as this abbreviated protocol has 100% sensitivity and 98.6% specificity for detecting spinal cord compression while reducing scan time 4
• Standard T1 and T2-weighted sequences in both sagittal and axial planes should be included for complete evaluation 2
• IV contrast is NOT needed for routine evaluation of cord compression, but should be added only if malignancy, infection, or inflammation is clinically suspected 1, 2

Alternative Imaging When MRI is Contraindicated or Unavailable

If MRI cannot be performed immediately:

• CT myelography is the best alternative as it assesses the patency of the spinal canal, thecal sac, subarticular recesses, and neural foramina 1
• CT myelography is particularly useful for surgical planning in patients with severe scoliosis where bony anatomy needs detailed visualization 1
• The disadvantage is the requirement for lumbar puncture and intrathecal contrast injection 1

Plain CT without contrast has limited utility - while it can detect whether cauda equina compression is present (50% thecal sac effacement predicts significant stenosis), it cannot adequately characterize the spinal cord itself or identify the etiology of compression 1

Critical Clinical Pitfalls to Avoid

• Do not rely on neurological examination alone - studies show that physical examination has only 62% accuracy for diagnosing intraspinal abnormalities in scoliosis patients, and absence of neurological symptoms does not rule out cord compression 1, 2
• Do not assume the sensory level corresponds to the compression level - in 21% of patients, the sensory level is four or more segments below the actual MRI-documented compression site 3
• Do not image only the clinically suspected region - whole spine MRI is mandatory because 25% of patients have compression at multiple levels, with 69% involving more than one spinal region 3
• Do not delay imaging for patients with red flags including rapid curve progression (>1° per month), functionally disruptive pain, focal neurological findings, or new bowel/bladder symptoms 5, 2

When to Proceed Without MRI

Treatment may be initiated based on focal radiographic changes and consistent neurology only in these specific circumstances:

• MRI is absolutely contraindicated (e.g., incompatible implanted devices) 3
• MRI will be significantly delayed and the patient has progressive neurological deterioration requiring immediate intervention 3
• The patient has a very poor prognosis where the additional information from MRI would not change management 3

However, even in these scenarios, every effort should be made to obtain MRI or CT myelography before definitive surgical intervention to avoid missing additional levels of compression or unexpected pathology 3