What is the treatment for impingement upon the anterior thecal sac and spinal cord?

Treatment of Impingement Upon the Anterior Thecal Sac and Spinal Cord

Immediate surgical decompression is mandatory for patients with thecal sac and spinal cord impingement who present with neurologic deficits, as outcomes are significantly worse with delayed intervention. 1

Initial Assessment and Imaging

MRI without IV contrast is the first-line diagnostic modality to evaluate the extent of thecal sac and spinal cord compression, as it accurately depicts soft-tissue pathology and assesses spinal canal patency. 2, 3

• For thoracic spine involvement with myelopathy or radiculopathy, MRI thoracic spine without IV contrast is the initial study of choice to identify compressive etiologies including disc herniations, facet arthropathy, or ligamentum flavum ossification. 2
• If MRI is contraindicated or unavailable, CT without IV contrast can effectively determine whether cauda equina compression is present, with 100% sensitivity for detecting significant stenosis. 3, 4
• CT myelography can assess spinal canal/thecal sac patency and is useful for presurgical planning, though it requires lumbar puncture for intrathecal contrast injection. 2

Immediate Medical Management

High-dose dexamethasone (96 mg/day IV) should be initiated immediately upon presentation, even before imaging confirmation, if clinical suspicion for spinal cord compression is high. 1

• This corticosteroid regimen improves ambulatory outcomes, with 81% of ambulatory patients remaining ambulatory versus 63% without steroids. 1
• Steroids should not be withheld while awaiting imaging if neurologic deficits are present. 1

Surgical Intervention

Urgent surgical consultation and decompressive surgery should be performed as soon as possible to prevent irreversible neurological deterioration. 1

• For symptomatic thoracic disc herniations causing myelopathy, surgical indication includes severe intractable pain or progressive/severe myelopathy. 2
• Decompressive surgery followed by radiation therapy benefits patients who are <65 years old, have single-level compression, neurologic deficits present <48 hours, and predicted survival ≥3 months. 1
• Patients with complete paralysis at presentation have much shorter life expectancy and poorer functional outcomes regardless of treatment approach. 1

Conservative Management Considerations

Conservative management is only appropriate for patients without neurologic deficits and with <50% thecal sac effacement on imaging. 3

• For lumbar stenosis without cauda equina syndrome, patients who fail 6 weeks of conservative therapy and remain surgical candidates should undergo MRI lumbar spine without IV contrast for definitive evaluation. 2
• Physical therapy and core strengthening may be attempted in patients with mild stenosis and no red flag symptoms. 5

Critical Pitfalls to Avoid

• Never delay surgical intervention when neurologic deficits are present, as outcomes deteriorate rapidly with delayed decompression. 1
• Do not assume all thecal sac compression requires immediate surgery—patients with <50% effacement and no red flags can be managed conservatively with close outpatient follow-up. 3
• Do not discharge patients with ≥50% thecal sac effacement without arranging urgent MRI, as nearly half may have cauda equina impingement requiring surgical decompression. 3, 4
• Avoid relying on radiography alone, as it is insensitive for evaluating the epidural space and spinal cord compression. 3

Radiation Therapy for Malignant Compression

For malignant spinal cord compression, various fractionation schemes are equally effective (30 Gy in 10 fractions, 37.5 Gy in 15 fractions, or 40 Gy in 20 fractions). 1

• Ambulatory outcomes with radiation therapy alone show 92-94% of ambulatory patients remain ambulatory, but only 12-14% of paraplegic patients regain ambulation. 1
• MRI of the entire spine with and without contrast is appropriate for known malignancy with new back pain to assess for multilevel disease. 1