Spinal Epidural Abscess
Spinal epidural abscess is a serious infection requiring urgent evaluation, characterized by a purulent collection in the epidural space of the spinal canal. It usually develops through hematogenous spread, spread from adjacent structures or after spinal procedures. The classic triad is back pain, fever and neurological deficit, although the full triad is seen in a minority of patients. Without early diagnosis and treatment it can lead to permanent neurological damage.
Ultimo aggiornamento: 2026-06-07
Definition and Pathogenesis
Spinal epidural abscess is a focal purulent collection formed by bacterial, or rarely fungal, organisms in the epidural space between the bony wall of the spinal canal and the dura mater. There are three main mechanisms: hematogenous spread (from a distant focus of infection), direct spread from adjacent structures (vertebral osteomyelitis, discitis, paravertebral abscess) and procedural/traumatic causes (epidural anesthesia, lumbar puncture, spinal surgery). In a proportion of cases no clear source can be identified.
Risk Factors and Organisms
The main risk factors are diabetes mellitus, immunosuppression (HIV, malignancy, corticosteroid use), intravenous drug use, chronic renal failure, advanced age and a history of previous spinal surgery/trauma. The most common organism is Staphylococcus aureus, and the proportion of methicillin-resistant strains (MRSA) is increasing. Streptococci, gram-negative bacteria and anaerobes are other organisms; in endemic regions tuberculosis (secondary to Pott disease) and brucella may also be seen. The abscess most often lies in the thoracic region.
Clinical Stages and Symptoms
The disease classically progresses through four stages: first focal and severe back pain (Stage 1), then radicular pain due to nerve root irritation (Stage 2), then motor weakness and sensory loss (Stage 3) and finally paralysis (Stage 4). The rate of progression is highly variable; it occurs within hours in some patients and over weeks in others. Systemic findings such as fever, chills-rigors and general malaise may accompany. Sphincter dysfunction (urinary retention, incontinence) is a sign of an advanced stage.
Diagnosis
Normal white cell and CRP values do not exclude the diagnosis, but elevated CRP and sedimentation rate are supportive; blood cultures should be obtained before treatment. Contrast-enhanced magnetic resonance imaging (MRI) is the gold standard and shows the epidural collection, peripheral wall (ring) enhancement, cord compression and any accompanying osteomyelitis/discitis. Because multilevel involvement is common, the entire spinal canal should be imaged. Contrast-enhanced CT is used when MRI cannot be performed. For the definitive organism, culture of abscess material obtained at surgery is valuable.
Treatment
Treatment requires a multidisciplinary and urgent approach. In the presence of neurological deficit or in progressing cases, surgical decompression and drainage (usually laminectomy with evacuation of the abscess and copious irrigation) is the gold standard treatment; early surgery improves prognosis once a motor deficit develops. Long-term (usually 4-8 weeks) parenteral antibiotics are given; empirical therapy includes vancomycin with a cephalosporin and, when needed, anaerobic cover, and is targeted after culture results. Treatment duration is longer when osteomyelitis is present. Source control and management of comorbidities (such as diabetes) are important.
Conservative Treatment and Prognosis
Conservative (non-surgical) treatment may be attempted only in selected cases (patients without neurological deficit, with a small abscess and at high surgical risk); close clinical and radiological follow-up is essential, and surgery is undertaken if there is no response. Prognosis is closely linked to the timing of diagnosis and treatment. Recovery rates are high in patients treated early (before a neurological deficit develops); the risk of permanent deficit increases markedly in those who develop prolonged complete paralysis. For this reason, progressive back pain, fever and neurological symptoms require urgent evaluation. Outcomes are individual and cannot be guaranteed.
Riferimenti
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:380-386.
- Darouiche RO. Spinal epidural abscess. N Engl J Med. 2006;355(19):2012-2020.
- Berbari EF, Kanj SS, Kowalski TJ, et al. Infectious Diseases Society of America clinical practice guidelines for the diagnosis and treatment of native vertebral osteomyelitis. Clin Infect Dis. 2015;61(6):e26-e46.
- Reihsaus E, Waldbaur H, Seeling W. Spinal epidural abscess: a meta-analysis of 915 patients. Neurosurg Rev. 2000;23(4):175-204.
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