Patrick and Lauren go straight into talking about the evidence, but let us define spinal epidural abscess (SEA) first. SEA is a pyogenic infection of the epidural space that can mechanically compress on the spinal cord. It can lead to devastating outcomes including neurological deficits or even death. The gold standard for diagnosis
is magnetic resonance imaging (MRI) with gadolinium enhancement (contrast). Given that most of the time it is located in the lower thoracic or lumbar spine, some have advocated for MRI from T10 through L5. However, case reports
demonstrate infection at higher levels including the cervical spine so imaging should be considered where there are findings in the appropriate context. Lauren generally recommends imaging the adjoining area. If the patient has lower back pain for example, get both MRI of the lumbar and thoracic spine. She may only localize to one area if there is isolated pain at one extreme (high on the neck or very low in the back).
Fortunately, Patrick did a talk in September 2018 about SEA and vertebral osteomyelitis (VO). His many resources and citations, including that talk can be found on this Google Drive. Most of the citations for this discussion (unless directly linked) are in those papers on his drive.
The main challenge with SEA and VO is diagnosis. Not everyone with back pain needs MRI and especially in the emergency settings. However, here are the main patients to consider for emergent MRI.
- New or acute exacerbation of chronic back pain without other cause (such as fall, pyelonephritis, or herpes zoster infection to area) with a recent history of bacteria or recent spinal infection (such as VO or discitis).
- Back pain with a history of intravenous drug abuse (IVDA), spinal procedure or injection in the last six months, an indwelling vascular catheter or foreign body of the spine, or emergency department (ED) visit/antibiotics in the last 30 days.
- For those without these risk factors, back pain without other cause and a documented or reported fever (37 Celsius or 100.4 Fahrenheit) and an elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).
Lauren went over risk factors that has been observed in patients with SEA:
- 35% had antibiotics in the last 30 days
- 20% had a history of IVDA
- 20% had indwelling catheters
- 20% had alcohol (EtOH) abuse
- 20% had chronic kidney disease (CKD)
- 10% had spinal instrumentation in the past year
There are also less commonly listed risk factors to consider which are either overly sensitive or less common in the rate of occurrence partly due to these being smaller populations:
- End stage disease (liver, lungs, renal, cardiac, etc)
- Undomiciled (homeless)
- Oncology/transplant patients
- Chemically dependent (drugs, EtOH, etc)
- Other immunocompromised states such as human immunodeficiency virus (HIV)
- Patients with chemotherapy or dialysis ports
- Those with indwelling and long term Foley catheter use
Check out some additional resources such as EP Monthly, Core EM, and Academic Life in Emergency Medicine (ALiEM) for even more information. Also, the University of Michigan has a quality management program going over VO, discitis, and SEA so check out that document, too (PDF included below).
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