Back pain, fever and a neurological deficit: MRI of the WHOLE spine with contrast shows the enhancing epidural collection, its craniocaudal extent, cord compression and the source — discitis, facet joint or psoas.
Orient first
- Classic triad (back pain, fever, deficit) is present in a minority; IV drug use, diabetes and recent spinal procedures are the risk factors.
- Skip lesions are common, so the whole spine is imaged.
- Phlegmon (diffusely enhancing tissue) and abscess (rim-enhancing fluid) are both treated, but abscess volume and compression drive surgery.
Acquire the study
- MRI whole spine: sagittal T1, T2 and STIR; axial T2 at affected levels; post-contrast fat-saturated sagittal and axial T1; DWI where available.
The manoeuvre
- Sagittal STIR/T2: discitis-osteomyelitis (disc hyperintensity, endplate erosion) as the likely source.
- Post-contrast fat-saturated T1: rim-enhancing epidural collection vs uniformly enhancing phlegmon; measure the craniocaudal extent in vertebral levels.
- Axial T2 and post-contrast T1: canal compromise, cord or cauda equina compression, cord signal change.
- DWI: restricted diffusion in the collection supports pus.
- Paraspinal and psoas muscles: abscess.
What confirms it
- A rim-enhancing epidural collection (or enhancing phlegmon) with compatible clinical signs, extent and compression stated.
What licenses you to exclude it
- A contrast-enhanced whole-spine MRI without epidural enhancement or collection excludes epidural abscess.
The classic misread
- Imaging only the painful segment and missing a skip abscess.