A spinal epidural abscess should be considered when back pain is accompanied by fever and spinal tenderness. Blood tests and infection parameters (leukocyte count, CRP, temperature, etc.) may initially be normal. If neurological deficits are present or develop, rapid surgical intervention is indicated, making this a neurosurgical emergency.

Epidemiology

The incidence is 2 per 10,000 emergency hospital admissions per year. The average age is between 40 and 65 years. The thoracic spine is most commonly affected (80%), followed by the lumbar (35%) and cervical regions (15%). Most abscesses are located posterior to the spinal cord (~80%), and between 1 and 13 spinal levels may be involved.

Clinical presentation

Typically, there is severe localized spinal pain with muscle tension and tenderness. Early neurological deficits include mild to moderate bladder and bowel dysfunction. Radicular pain usually appears about 3 days after the onset of back pain. After another 4–5 days, limb weakness develops, and within 24 hours, paraplegia or tetraplegia may occur. Fever, chills, and elevated infection parameters can occur but are paradoxically not always present.

Radiological findings

MRI with contrast is the diagnostic method of choice. On native T1 MRI, the abscess shows low signal intensity; on T2, high signal intensity. With contrast, a typical enhancing rim with a necrotic center is seen. Homogeneous enhancement may occur with multiple confluent microabscesses. The psoas region (psoas abscess), paravertebral muscles, vertebral bodies, and intervertebral discs (spondylodiscitis) should also be assessed due to possible involment.

Differential diagnoses

• Meningitis
• Acute transverse myelitis
• Vertebral osteomyelitis
• Discitis
• Disc herniation
• Spinal tumor
• Spinal metastasis

Special considerations

Antibiotic therapy

Initial broad-spectrum antibiotics should be started immediately after local surgical intervention, following local guidelines. Preoperative administration is not recommended due to possible falsification of cultures or lack of pathogen detection. Therapy should be adjusted to the specific pathogen and lasts 6–10 weeks, with at least 10–14 days of initial intravenous administration.

Pathogens

Staphylococcus aureus is found in up to 50% of cases, usually via hematogenous spread. In 30–40% of cases, no pathogen is detected.

Sources of infection

• Skin lesions
• Intravenous drug abuse
• Urinary tract infections
• Respiratory infections
• Pharyngeal or dental abscesses
• Iatrogenic causes (post-surgery, injections)

Risc factors

• Type I or II diabetes mellitus
• Intravenous drug abuse
• Chronic kidney failure
• Chronic alcohol consumption
• Immunosuppression

Indication for surgery

Early surgical decompression (interlaminar fenestration, hemilaminectomy, laminectomy), sample collection, and local treatment combined with antibiotics is the therapy of choice. Rapid clinical deterioration can occur with antibiotic therapy alone. Patients with early neurological deficits are neurosurgical emergencies. Non-surgical management may be considered only in patients with high perioperative risk, extensive intraspinal spread over multiple levels, or paralysis for more than 3 days.

Outcome

In 5–30% of cases, the course is fatal. Older patients or those with severe motor deficits before surgery tend to have a much worse prognosis. Preoperative paralysis rarely results in full recovery. Increased mortality is mainly due to bedridden status and complications (e.g., pulmonary embolism) or systemic infection and initial infection focus.

References

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