42-year-old female. Hx of IVDU, now with back pain and weakness.
Discitis-osteomyelitis (spondylodiscitis)
Here's the most common discitis-osteomyelitis scenario: Staph aureus gains access to the bloodstream, gets lodged in a vertebral endplate capillary, and then spreads into the vertebra, the adjacent disc, and the vertebra across the disc. That’s a functional model for how patients commonly end up with discitis and osteomyelitis involving two adjacent vertebrae (together, sometimes called one vertebral unit). Of course, it’s possible to have just discitis or vertebral osteomyelitis, but most of the HMC cases we reviewed showed both conditions. In the majority of these, there’s a paraspinal and/or epidural phlegmon or abscess, which can result in cord compression. Progressive infection eventually leads to disc collapse and necrosis of the vertebrae. The post-gadolinium fat-suppressed images will show intense enhancement of the disc, bone, and the adjacent soft tissues, as you’d expect with any infection.
Cord compression requires a neurosurgery consult to determine if emergent decompression is needed. If not, conservative management with IV antibiotics may suffice.