Spinal epidural abscess can be difficult to diagnose. Fever and back pain should raise suspicion for epidural abscess and prompt urgent imaging to rule it out. Fever is not universally present, so a high index of suspicion is required, especially in patients with leg weakness, loss of sensation, or loss of bowel/bladder control. Timely recognition with emergent surgical consultation is crucial to avoid complications such as paralysis and/or sepsis.
Patients often (but do not always) have one or more of the following:
spinal abnormality or trauma (including surgery, drug injection, or catheter placement)
local or systemic infection
Staphylococcus aureus causes about 66% of spinal infections.
Other causes include:
coagulase-negative staphylococci, such as Staphylococcus epidermidis
gram-negative bacteria, particularly Escherichia coli (usually subsequent to urinary tract infection) and Pseudomonas aeruginosa (especially in injection-drug users)
rarely caused by anaerobic bacteria, actinomycosis or nocardiosis, mycobacteria, fungi, or parasites (echinococcus and Dracunculus)
Bacteria can spread to the epidural space via contiguous spread or hematogenous dissemination and can cause systemic complications as demonstrated in the following figure:
full history plus physical examination
complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)
urine cultures and chest radiography if other sources of infection are suspected
MRI (the imaging modality of choice)
CT myelography (also highly sensitive but more invasive and reserved for patients with MRI contraindications; requires analysis of cerebrospinal fluid [CSF])
no routine lumbar puncture (often adds little to diagnosis and is associated with a slight potential risk)
The following table offers common pitfalls and recommended approaches in diagnosing and treating spinal epidural abscess:
Spinal epidural abscess is generally managed with emergency decompressive surgery and antibiotics. However, if a patient refuses surgery, has high operative risk, or has already had extended duration of paralysis, management with antibiotics can be considered.
Vertebral osteomyelitis is another cause of back pain and infection, and it may present with accompanying epidural abscess or alone. Causative organisms are similar to those of epidural abscess.
Read more on diagnostic workup and management of vertebral osteomyelitis in Clinical Pearls & Morning Reports.
The following table suggests antibiotic regimens for common causes of osteomyelitis: