Vertebral Discitis-osteomyelitis (VDO)

Diagnosis
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  • 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
  • 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
  • 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
  1. 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
  2. Dagirmanjian A, Schils J, McHenry M, et al. MR imaging of vertebral osteomyelitis revisited. AJR Am J Roentgenol 1996; 167(6):1539-1543