Spinal epidural abscess represents loculated infection within the fat-filled space that separates the spinal dura and arachnoid. The condition is a neurologic and neurosurgical emergency that, if unrecognized, may cause devastating neurologic injury or death. Because of its infrequent occurrence, the possibility of epidural abscess tends not to be considered in patients presenting with fever and back or neck pain; for this reason, failure to recognize this spinal epidural abscess makes this condition a significant source of litigation for malpractice. In this article, the author reviews the pathogenesis, clinical features, diagnosis, and treatment of this disorder.
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• Acute spinal epidural abscess characteristically presents with a consistent sequence of clinical symptoms and signs: severe focal pain, often unrelieved by narcotics, followed by radicular pain, followed by signs of spinal cord compression.
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• Chronic epidural abscesses may exhibit a similar sequence of symptoms and signs, but these may develop slowly over time. The most common presentation of chronic epidural abscess is that of a compressive lesion, sometimes with minimal, if any, pain.
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• Cervical or thoracic spinal epidural abscess may occur as a complication of SARS-CoV-2 infection, including in patients with mild disease.
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• Treatment of spinal epidural abscess, in most cases, involves both antibiotic treatment and surgical drainage. Delay in diagnosis and treatment may result in death or profound, irreversible neurologic impairment.
Historical note and terminology
The first report of spinal epidural abscess is credited to Albers (24). Ducheck termed the condition "peripachymeningitis" in 1853, a name changed by later reports to "pachymeningitis externa." In 1926, Dandy provided the first thorough review of the condition and its pathogenesis, including the observation that usually invasive organisms, such as Staphylococcus aureus, could produce extremely protracted infections within the spinal epidural space (24). In 1948, Heusner delineated the clinical features of spinal epidural abscess in a classical and still valid report (46).
Initially, diagnosis of spinal epidural abscess was based on neurologic localization alone, and treatment was purely surgical. Myelography provided the first means of localizing spinal epidural abscesses with some precision, with CT offering an additional diagnostic tool. MRI, with its ability to visualize the cord over its entire length, has replaced both myelography and CT as the diagnostic method of choice. For the most part, spinal epidural abscess remains a surgical condition. In some patients, however, CT-guided needle aspiration has been used in place of surgery, and the ability to monitor an abscess with serial MRI examinations has made it possible to treat selected patients with small epidural abscesses using antibiotics alone (65; 43; 79; 40; 83; 108; 113; 84). Guidelines for the use of CT-guided aspiration and nonsurgical therapy, however, are still being developed (117; 74; 93; 83; 113; 84).