Chapter 7-10: Spinal Epidural Abscess

TEXTBOOK PRESENTATION

The classic presentation is a patient with a history of diabetes or injection drug use who has fever and back pain, followed by neurologic symptoms (eg, motor weakness, sensory changes, and bowel or bladder dysfunction).

DISEASE HIGHLIGHTS

1. Pathogenesis

   1. Most patients have 1 or more predisposing conditions.

      1. Underlying disease (diabetes mellitus [30% of patients with epidural abscess], injection drug use [4–37%], end-stage renal disease [2–13%], immunosuppressant therapy [7–16%], cancer [2–15%], HIV [2–9%])

      2. Invasive spine intervention, (surgery, percutaneous spine procedure [14–22%]) or trauma

      3. Potential local or systemic source of infection (skin or soft tissue infection, endocarditis, osteomyelitis, urinary tract infection, injection drug use, epidural anesthesia, indwelling vascular access)

   2. Infection occurs by hematogenous spread (most common), direct spread from an infection in the vertebral column or paraspinal soft tissues, or by direct inoculation during a procedure or trauma.

   3. Staphylococcus aureus is the organism in 66% of cases.

      1. Other organisms include Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa.

      2. Anaerobes, mycobacteria, fungi, and parasites are occasionally found.

2. Clinical manifestations

   1. Classic triad of fever, spine pain, and neurologic deficits are found in only 13–37% of patients.

   2. Back pain is present in 75–95% of patients.

   3. Fever is present in about 50% of patients.

   4. Neurologic deficits are found in about 33% of patients.

   5. Occur more commonly in posterior than anterior epidural space and more commonly in the thoracolumbar than cervical areas.

   6. Generally extend over 3–5 vertebrae.

3. Staging

   1. Stage 1: back pain at the level of the affected spine

   2. Stage 2: nerve root pain radiating from the involved spinal area

   3. Stage 3: motor weakness, sensory deficit, bladder/bowel dysfunction

   4. Stage 4: paralysis

   5. Rate of progression from 1 stage to another is highly variable.

   6. The most important predictor of the final neurologic outcome is the neurologic status before surgery, with the postoperative neurologic status being as good as or better than the preoperative status.

EVIDENCE-BASED DIAGNOSIS

1. ESR and C-reactive protein are usually elevated.

2. Leukocytosis is present in about 66% of patients.

3. Bacteremia is present in 60% of patients.

4. MRI with gadolinium is the best imaging study, with a sensitivity of > 90%. CT myelogram is an alternative if MRI cannot be performed.

   A normal white blood cell count and negative blood cultures do not rule out spinal epidural abscess.

TREATMENT

1. CT-guided or open biopsy, followed by percutaneous or surgical decompression and drainage

2. Antibiotics