Spinal subdural empyema is a rare infection that may rapidly produce spinal cord infarction and necrosis. Although the spinal subdural empyema usually arises as a consequence of staphylococcal bacteremia, it may also be associated with spinal epidural abscess, disc space infections, decubitus ulcers, persistent dermal sinus, osteomyelitis, spinal surgery, epidural anesthesia, or acupuncture. In many less developed countries, it may occur as an occasional complication of tuberculosis. Prompt recognition and treatment are essential in avoiding a fatal outcome or severe neurologic disability. In this article, the author reviews the pathogenesis, clinical features, diagnosis, and treatment of this highly destructive, potentially lethal condition.
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• Spinal subdural empyema represents infection within the potential space between dura and arachnoid.
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• The spinal subdural space has no barriers to prevent spread of infection, so that a spinal subdural empyema can rapidly expand to involve multiple spinal levels. Because of this a spinal subdural empyema may produce extensive cord injury and profound neurologic deficit within 48 to 72 hours.
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• Staphylococcus aureus is the causative agent in 50% of cases in Western countries, with a smaller number of cases caused by S epidermidis, aerobic or facultative streptococci, Streptococcus pneumoniae, or, less frequently Bacteroides or Fusobacterium species. Pseudomonas may cause spinal subdural empyema in the setting of neurosurgical procedures.
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• Tuberculosis may be the cause of spinal epidural abscess and should be kept in mind in patients from countries where the disease is still common.
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• Gadolinium-enhanced MRI is the diagnostic procedure of choice and may require imaging of the spine over its entire length.
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• Spinal subdural empyema is an absolute indication for immediate surgery. Initial antibiotic therapy should be directed against S aureus and other gram-positive organisms and should include vancomycin. Ceftazidime and gentamicin should be added if there is any question of Pseudomonas aeruginosa or other gram-negative organisms, and metronidazole should be used if infection by Bacteroides fragilis is suspected.
Historical note and terminology
Although a case that may have represented a spinal subdural empyema was reported by Levy in 1849, the earliest report clearly defining spinal subdural empyema as a distinct clinical entity is that of Lowenburg in 1918 (01). Important case reports and series were published by Bennett and Keegan in 1928 (12), Abbott in 1953 (01), Fraser and colleagues in 1973 (19), Brock and Bleck in 1992 (11), and Schneider and Givens in 1998 (43). Levy and colleagues have provided a useful review of MRI findings (30). Spinal subdural empyema is a rare entity. Only a small number of case reports exist, and only 1 detailed case series and literature review has been published (41). It is of note, however, that Harris and colleagues, in a series of 31 patients with localized central nervous system infections, found 1 spinal subdural empyema, suggesting that spinal subdural empyema may constitute a larger portion of space-occupying central nervous system infections than is usually supposed (22).