Spinal epidural abscess

Background

• Infection of the epidural space, between the dura mater and bone, in the spine
• Acquired from contiguous spread (e.g. discitis, otitis media/sinusitis/mastoiditis, direct inoculation (e.g. spinal anaesthesia or neurosurgery), or hematogenous spread
• Risk factors include intravenous drug use, hemodialysis, diabetes mellitus, and older age

Microbiology

• Staphylococcus aureus is most common cause (63%)
• Gram-negative bacilli (16%)
• Streptococci (9%)
• Coagulase-negative staphylococci (3%), mostly in patients with hardware
• Anaerobes (2%)
• Fungal or parasitic (1%)
• Unknown (6%)

Etiologies

• Idiopathic (30%)
• Skin and soft tissue infection (22%)
• Spinal surgery or procedure (12%)
• Injection drug use (10%)
• Other sources including epidural catheters (8%)
• Bone and joint infections (7%)
• Urinary tract (3%)
• Upper respiratory tract (3%)
• Sepsis (2%)
• Abdomen (2%)
• Intravascular catheter (<1%)

Clinical Manifestations

• Severe low-back pain often worse with palpation
• Fever
• Malaise
• Neurologic deficits associated with mass effect on spinal cord, interruption of arterial supply, venous thrombosis, or toxin

Staging of Spinal Epidural Abscess

• Stage 1: back pain at the level of the affected spine
• Stage 2: nerve-root pain radiating from the involved spinal area
• Stage 3: motor weakness, sensory deficit, and bladder and bowel dysfunction
• Stage 4: paralysis

Diagnosis

• Usually made by MRI (or CT with contrast)
• Blood cultures may be helpful
• Cultures from the abscess fluid, if possible

Management

• May need urgent neurosurgical drainage if neurological symptoms
• Intravenous antibiotics, ideally after blood cultures are drawn
• Typical empiric antibiotics are ceftriaxone and vancomycin