Spinal Epidural Abscesses

Despite advances in the diagnosis and treatment of neurosurgical diseases, spinal epidural abscesses (SEA) remain challenging. The diagnosis is complex, treatments are controversial, and the potential for adverse outcomes is significant. SEA accounts for 2 of every 10,000 of hospital admissions, an incidence which has doubled in the past twenty years. Reasons which may account for this include an aging population, increased IV drug use, and increase in number of vascular and spinal procedures. SEA can arise from an underlying medical condition, such as diabetes mellitus, alcoholism, chronic obstructive pulmonary disease (COPD), or HIV infection. Loci for SEA can be formed by other spinal abnormalities or by prior invasive spinal procedures, including epidurals, nerve blocks, or steroid injections. Sources for systemic infection may include vascular access catheters, IV drug use, or chronic UTI. 50% of spinal epidural infections have hematogenous origin, 30% arise from the skin or connective tissue, and 20% are unclassified. Common pathogens include S. aureus and P. aeruginosa. From 15% to 40% of SEA may be due to MRSA. In cases of spine trauma or spinal surgery, S. epidermidis may also be a pathogen. 79% of SEA appear dorsal to the spinal cord. A possible explanation for this finding is that the largest extent of the epidural space lies posterior to the nerve roots. The 21% that appear anterior are often associated with vertebral discitis and/ or osteomyelitis. Achieving correct diagnosis in cases of SEA may be challenging. 50% of epidural spinal abscesses are initially misdiagnosed. The most common presenting symptom is back pain, present in up to 85% of patients. Fever is present in up to 50%. Less common symptoms are paresthesias, sensory deficits, radicular pain, or motor deficits. SEA can occur spontaneously in patients with increased co-morbidi-ties. In post-operative patients, SEA may take days to weeks to appear. A dorsal SEA results from the spontaneous seeding of the dorsal epidural fat. As the abscess enlarges, neural compression may occur. Conversely, a ventral SEA may result from either spontaneous seed-ing of the ventral epidural fat or seeding of the disc space with secondary extension into the ventral epidural space. A ventral SEA is more likely to present with systemic symptoms (i.e., fevers, septicemia) prior to presentation of neurological deficits. The best way to diagnose SEA is to approach high-risk patients with suspicion. The neuro-logical exam may aid in localizing the level of spinal involvement in cases …