What it is
The thoracic spinal cord carries all motor and sensory signals between the brain and the lower body. Compression in this region — from disc herniation, bone spur formation, tumor, or ligament ossification (OPLL or OLF) — can produce myelopathy: progressive dysfunction of the cord manifesting as lower extremity weakness, spasticity, gait difficulty, and eventually bladder and bowel involvement.
Because thoracic cord compression affects a long segment of the cord's output, the consequences can be more diffuse than cervical myelopathy. The legs are affected first; with significant compression, the patient may eventually be unable to walk without assistance.
Ossification of the Ligamentum Flavum
A common and under-recognized cause of thoracic myelopathy is ossification of the ligamentum flavum (OLF) — calcification of the ligament behind the spinal cord that progressively narrows the canal. It is more common in patients of East Asian descent but occurs across all populations. OLF can be subtle on standard MRI and requires CT for full characterization.
Surgical treatment
When the imaging findings correlate with the clinical picture, surgical decompression is typically indicated. The approach depends on where the compression is coming from:
- Posterior compression (OLF, facet hypertrophy): addressed from behind with laminectomy
- Anterior compression (disc herniation, bone spur): requires a more complex lateral or anterior approach to avoid cord manipulation
Recovery after decompression depends on the severity and duration of cord compression before surgery. Early intervention generally produces better outcomes.