Spinal tuberculosis is the most common skeletal manifestation of TB, usually involving the thoracic and lumbar spine. Early recognition on imaging is crucial to prevent deformity and neurological deficits.
📍 Typical Sites of Involvement
- Thoracic > Lumbar > Cervical spine
- Paradiscal involvement (most common) → infection starts at anterior vertebral endplates adjacent to disc.
- Central, anterior, posterior, and skip lesions are less common patterns.
🖼️ Imaging Features
1. X-ray (Late changes)
- Vertebral body destruction & collapse
- Reduced disc space
- Kyphotic deformity / gibbus
- Paravertebral soft tissue shadow (cold abscess)
2. CT Scan
- Bony detail:
- Endplate erosions, lytic lesions
- Sequestra (dead bone fragments)
- Cortical breach and vertebral collapse
- Paraspinal/epidural collections with peripheral rim enhancement
- Helpful for biopsy guidance
3. MRI (Modality of choice)
MRI detects early marrow and soft tissue changes before X-ray/CT.
Typical MRI findings:
- Bone marrow changes: T1 hypointense, T2/STIR hyperintense vertebral bodies
- Disc involvement: Early loss of disc height (distinguishes from metastasis)
- Paraspinal abscess: Smooth, thin-walled, T2 hyperintense with rim enhancement; may extend along psoas (“psoas abscess”)
- Epidural extension: Causes thecal sac compression → cord edema or myelopathy
- Subligamentous spread: Infection tracks beneath anterior longitudinal ligament across multiple levels
- Cold abscesses: Large with thin walls, minimal surrounding inflammation (vs pyogenic spondylitis)
- Complications: Gibbus deformity, cord compression, syrinx, sinus tracts
🔎 Differentiation: TB vs Pyogenic vs Metastasis
| Feature | Tuberculosis | Pyogenic Spondylitis | Metastasis |
|---|---|---|---|
| Disc involvement | Early, common | Early, severe | Usually spared until late |
| Abscess | Large, thin-walled, cold abscess | Small, thick-walled, enhancing | Rare, small |
| Vertebral involvement | Multiple contiguous bodies | Usually 1–2 levels | Skip lesions, non-contiguous |
| Paraspinal spread | Subligamentous, long-segment | Localized | Localized |
| Kyphosis | Common, severe (gibbus) | Less severe | Rare |
🧠 Teaching Points
- MRI is best for early diagnosis and cord evaluation.
- Disc involvement + large paraspinal cold abscess → strongly favors TB over metastasis.
- Always evaluate for skip lesions, especially in endemic regions.
- Differentials: Brucella spondylitis, pyogenic spondylitis, lymphoma, metastasis.
