Spinal osteomyelitis is an infection of the vertebral bones, often involving the adjacent intervertebral disc (discitis) and surrounding soft tissues. A spinal epidural abscess is a collection of pus in the space surrounding the spinal cord that can rapidly compress neural structures. Both conditions are serious and require prompt diagnosis and treatment.
Spinal osteomyelitis and epidural abscess are among the most urgent conditions affecting the spine. Severe cases can produce Cauda Equina Syndrome through rapid neural compression, and the resulting vertebral destruction can lead to Compression Fractures and spinal instability. In the chronic phase, infection-related scarring and inflammation may contribute to Arachnoiditis.
Causes
Bacterial infection.
The most common cause is bacterial spread through the bloodstream (hematogenous seeding) from a distant source of infection such as a urinary tract infection, skin infection, IV catheter, or dental procedure. Staphylococcus aureus — including MRSA — is the most frequently identified organism. Tuberculosis (Pott's disease) remains a significant cause worldwide.
Risk factors
Risk factors include diabetes, immunosuppression, intravenous drug use, recent spinal surgery or instrumentation, chronic kidney disease, and advanced age. These conditions impair the body's ability to fight infection and allow pathogens to establish themselves in spinal structures.
Symptoms
The classic presentation includes severe localized back pain, fever, and tenderness directly over the affected vertebrae. Pain is often constant and not relieved by rest — a key distinguishing feature from mechanical back pain. When a spinal abscess compresses the spinal cord or nerve roots, patients may develop rapidly progressive neurological deficits including weakness, numbness, and bowel or bladder dysfunction. This is a neurological emergency requiring immediate intervention.
Diagnosis
Laboratory studies including white blood cell count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and blood cultures are essential to identify infection and the causative organism.
MRI with contrast is the gold-standard imaging modality for spinal infection, clearly delineating the extent of bone involvement, disc infection, soft tissue spread, and any epidural abscess compressing neural elements. A cervical or lumbar spine MRI with gadolinium contrast will be obtained depending on the level of involvement. CT-guided biopsy of the affected vertebra or disc may be performed to obtain tissue for culture and guide antibiotic selection when blood cultures are negative.
Severity Classification
The urgency and approach to treatment depends on the extent of infection and the presence of neurological involvement.
- Uncomplicated osteomyelitis/discitis: Infection confined to the vertebrae and disc without abscess or neurological compromise.
- Osteomyelitis with epidural extension: Infection spreading to the epidural space, increasing risk of cord compression.
- Spinal epidural abscess with neurological deficit: A surgical emergency with risk of permanent paralysis if not promptly treated.
Treatments
Treatment requires a multidisciplinary approach involving infectious disease specialists, radiologists, and spine surgeons. Early diagnosis and treatment are critical to prevent irreversible neurological damage.
Identification of the causative organism guides antibiotic selection. Empiric broad-spectrum antibiotics are initiated promptly while awaiting culture results, then tailored based on sensitivities.
Antibiotic therapy: Most cases of spinal osteomyelitis without neurological compromise or abscess can be treated with prolonged intravenous followed by oral antibiotic therapy, typically for 6–12 weeks. Close monitoring with serial inflammatory markers and repeat imaging is essential to confirm treatment response.
Surgical treatment
Surgery is indicated when there is a spinal epidural abscess causing or threatening neurological deficit, failure of antibiotic therapy, significant vertebral instability, or inability to obtain tissue for diagnosis. Surgical options include CT-guided or open drainage of the abscess, debridement of infected tissue, and spinal stabilization with instrumented fusion when structural integrity is compromised.
Related Spine Conditions
- Cauda Equina Syndrome
- Compression Fracture
- Arachnoiditis
- Spinal Tumors
- Transverse Myelitis
- Back to all Spine Conditions
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