A 26 year old female presents with on and off fever and pain in lower dorsal spine since last 4 months.MRI of the spine reveals the following picture.Local tenderness is present.What would be the most probable diagnosis?
A. Disc Prolapse
B. Pyogenic Osteomyelitis
C. Pott disease
Ans:C. Pott disease
The image shows:Sagittal and axial MRI imaging showing subligamentous infection involving three contiguous vertebral levels: T10–T12 and large posterior epidural abscesses extending through epidural space to T5–T6 ….
Pott disease (tuberculous spondylitis)
- It refers to vertebral body and intervertebral disc involvement with tuberculosis (TB).
- The spine is the most frequent location of musculoskeletal TB, usually affects the lower thoracic and upper lumbar levels of the spine.
- Patients usually present with back pain, lower limb weakness/paraplegia and kyphotic deformity. Constitutional symptoms (fever and weight loss) are also common.
- The spine is involved due an hematogenous spread via the venous plexus of Batson 2.
- There is usually a slow collapse of one or usually more vertebral bodies, which spreads underneath the longitudinal ligaments.
- This results in an acute kyphotic or “gibbus” deformity.
- This angulation, coupled with epidural granulation tissue and bony fragments, can lead to cord compression. Unlike pyogenic infections, the discs can be preserved.
- In late-stage spinal TB, large paraspinal abscesses without severe pain or frank pus are common, leading to the expression “cold abscess”.
- Plain Radiograph:
- The earliest findings are radiolucencies and the loss of definition of the plate margins .
- The spread of infection is typically described as ‘sub-ligamentous’: beneath the anterior longitudinal ligament, usually sparing the posterior elements and often involving multiple levels.
- A reduction in vertebral height is often seen with the irregularity of the anterosuperior end plate being relatively early and subtle sign.
- Due to the subligamentous extension there may be some irregularity of the anterior vertebral margin. This is a classical appearance with TB spondylitis.
- Later, paraspinal collections can develop which can be remarkably large.Calcification in paraspinal masses is highly suggestive of TB.
- Advanced stages of the disease are characterized by: sclerosis from reparative processes, bony ankylosis, vertebral collapse and anterior wedging leading to progressive kyphosis and gibbus deformity
- Cross-sectional imaging is required to assess better the extent of involvement and particularly for the presence of an epidural component and cord compression.
- MRI is the modality of choice for this, with CT with contrast being a distant second.
- Differential diagnosis between tuberculous and pyogenic spondylitis is of clinical importance, but may be difficult on the basis of radiological findings alone.
- Findings not pathognomonic but favoring tuberculous etiology include: slow progression of lesions with late preservation of disk space, involvement of several contiguous segments, large intraosseous and paraspinal abscesses containing calcifications, and body collapse with kyphotic deformity.