Diagnosis Definition
- Vertebral discitis-osteomyelitis (VDO) is a continuum of disease, with both entities occurring at different times based on the age of the patient; disc infection happens first in young children, while osteomyelitis of the end plates occurs first in adults
- Most cases are caused by arterial hematogenous spread of infection; other causes include penetrating trauma, direct extension of infection, or interventional procedures
- In developed countries, Staphylococcus aureus is the most common infectious agent; worldwide, the most common agent is tuberculosis (Pott disease)
- VDO is more common in older patients and those with a history of intravenous drug abuse, compromised immune system, chronic alcoholism or steroid use, and diabetes
Imaging Findings
- MRI is the imaging study of choice and is more sensitive and specific than nuclear scintigraphy
- T1-weighted MR images of acute pyogenic VDO show hypointense signal of irregular and ill-defined end plates, adjacent vertebral bodies, and the infected disc, with corresponding irregular T2 hyperintense signal
- STIR imaging, which nulls out the signal from marrow fat, best shows T2 changes
- The disc and affected end plates enhance with contrast
Pearls
- Irregularity of the endplates will distinguish VDO from Modic type 1 degenerative changes
- MR imaging findings often lag behind early clinical signs of VDO and it’s resolution after treatment
- Extraosseous spread can extend into the paraspinal tissues, the epidural space, and the surrounding musculature, with abscess formation
References
- Hong SH, Choi JY, Lee JW, Kim NR, Choi JA, et al. MR Imaging Assessment of the Spine: Infection or an Imitation? RadioGraphics 2009; 29:599–612
- Dagirmanjian A, Schils J, McHenry M, et al. MR imaging of vertebral osteomyelitis revisited. AJR Am J Roentgenol 1996; 167(6):1539-1543
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