Epidural abscess is an unusual but important cause of back pain. Because this infection is a potentially crippling but treatable condition, early diagnosis and aggressive therapy are essential for good outcomes. Even with an indolent presentation, infected patients can still suffer devastating neurological complications related to delays in recognition and appropriate intervention.
CLASSIFICATION
Epidural abscesses can be separated anatomically into infections involving the spinal or cranial epidural space. Cranial epidural abscesses are recognized complications of cranial surgery or trauma; they may also complicate otorhinological infections or procedures. Because of the distinct differences between cranial and spinal infections, cranial epidural abscess and the related subdural empyema will not be discussed in the following review.
Spinal epidural infections can often be segregated into acute and chronic presentations. This simple categorization correlates, albeit imperfectly, with certain clinical and laboratory manifestations, bacteriology, cerebrospinal fluid (CSF) formulae, anatomic details, pathology, and pathogenesis (Table 77.1). The nontuberculous bacterial spinal epidural abscess constitutes the major focus of this review. Tuberculous, fungal, and parasitic abscesses of the spinal epidural space typically evolve more insidiously than pyogenic bacterial epidural abscesses. Other than candidial infections, these etiologies are more frequently encountered in tropical and subtropical resource-constrained regions of the world. Metastatic carcinoma and lymphoma represent common alternative diagnoses that can exactly mimic epidural infections but mandate very different treatments.