A spinal epidural abscess is a collection of infected material that forms inside the spinal canal but outside the dura, the protective covering around the spinal cord and nerves.
A spinal epidural abscess can occur in the cervical, thoracic, lumbar, or sacral spine. The condition is uncommon but potentially serious because the abscess can compress the spinal cord, nerve roots, or cauda equina.
Early diagnosis is important. Some patients can be treated with antibiotics alone, while others require urgent surgical drainage and decompression.
What Causes a Spinal Epidural Abscess?
Most spinal epidural abscesses are caused by bacteria.
The infection may reach the epidural space through:
- The bloodstream
- A nearby spinal infection
- Discitis or osteomyelitis
- Recent spine surgery
- Spinal injections or procedures
- Skin or soft-tissue infection
- Intravenous drug use
- Infected intravenous catheters
- Bloodstream infection
In some patients, no clear source is identified.
What Organisms Cause Spinal Epidural Abscess?
Staphylococcus aureus is one of the most common causes.
Other bacteria and, less commonly, fungal organisms may also be responsible.
Identifying the organism is important because treatment is usually guided by blood cultures, tissue cultures, or fluid obtained during surgery or image-guided aspiration.
Symptoms of a Spinal Epidural Abscess
Symptoms vary depending on the location and size of the abscess.
Possible symptoms include:
- Severe neck or back pain
- Fever or chills
- Pain radiating into an arm or leg
- Numbness or tingling
- Weakness
- Difficulty walking
- Loss of coordination
- Balance problems
More advanced compression can cause:
- Rapidly progressive weakness
- Paralysis
- Saddle numbness
- Urinary retention
- Loss of bladder control
- Bowel dysfunction
Importantly, not every patient has fever or all of the classic symptoms.
Persistent severe spinal pain with new neurologic symptoms should raise concern for a serious spinal infection.
Why Is a Spinal Epidural Abscess Dangerous?
The spinal canal contains important neurologic structures.
In the cervical and thoracic spine, an abscess can compress the spinal cord.
In the lumbar spine, it may compress the cauda equina or individual nerve roots.
Neurologic function can deteriorate quickly once significant compression develops.
The infection can also spread into:
- Vertebral bone
- Intervertebral discs
- Paraspinal muscles
- Bloodstream
For this reason, a spinal epidural abscess can become both a neurologic and systemic emergency.
Cervical Epidural Abscess
A cervical epidural abscess can compress the spinal cord in the neck.
Symptoms may include:
- Neck pain
- Arm pain
- Hand numbness
- Hand weakness
- Leg weakness
- Difficulty walking
- Loss of balance
Severe cervical spinal cord compression can affect both the arms and legs.
Because of the potential for rapid neurologic deterioration, cervical epidural abscesses with cord compression are treated particularly carefully.
Thoracic Epidural Abscess
A thoracic epidural abscess can compress the spinal cord in the mid-back.
Symptoms may include:
- Mid-back pain
- Pain around the chest or ribs
- Leg weakness
- Leg numbness
- Leg stiffness
- Poor balance
- Difficulty walking
Severe thoracic cord compression can lead to paralysis or bowel and bladder dysfunction.
Lumbar Epidural Abscess
A lumbar epidural abscess usually affects the nerve roots or cauda equina.
Symptoms may include:
- Severe low-back pain
- Leg pain
- Numbness
- Weakness
- Difficulty walking
- Saddle anesthesia
- Urinary retention
- Bowel or bladder dysfunction
Cauda equina compression requires urgent evaluation.
Who Is at Risk?
Spinal epidural abscess can occur in otherwise healthy patients, but risk is increased by:
- Diabetes
- Immunosuppression
- Cancer
- Chronic kidney disease
- Intravenous drug use
- Recent bloodstream infection
- Recent spine surgery
- Spinal injections
- Long-term intravenous catheters
- Discitis or osteomyelitis
- Older age
However, the absence of risk factors does not exclude the diagnosis.
How Is a Spinal Epidural Abscess Diagnosed?
Diagnosis usually involves a combination of physical examination, laboratory testing, and imaging.
MRI
MRI with contrast is generally the most important imaging study.
MRI can show:
- The epidural abscess
- Spinal cord compression
- Cauda equina compression
- Discitis
- Osteomyelitis
- Paraspinal infection
- Abnormal spinal cord signal
MRI also helps determine how many spinal levels are involved.
When symptoms suggest a more extensive infection, imaging of multiple spinal regions may sometimes be necessary.
Blood Tests
Laboratory testing may include:
- Complete blood count
- C-reactive protein
- Erythrocyte sedimentation rate
- Blood cultures
Inflammatory markers may be elevated, but no single blood test can rule the diagnosis in or out.
Blood cultures may identify the responsible organism.
Is Biopsy or Aspiration Necessary?
Sometimes.
If blood cultures are negative and the patient is neurologically stable, image-guided aspiration or biopsy may help identify the organism.
In patients who require surgery, tissue and fluid cultures can usually be obtained during the operation.
Treatment
Treatment depends on:
- Neurologic function
- Size and location of the abscess
- Degree of spinal cord or nerve compression
- Responsible organism
- Presence of osteomyelitis or discitis
- Spinal stability
- Overall medical condition
Treatment may include:
- Intravenous antibiotics
- Close neurologic monitoring
- Surgical drainage
- Spinal decompression
- Treatment of associated osteomyelitis or discitis
When Can a Spinal Epidural Abscess Be Treated Without Surgery?
Selected patients may be treated with antibiotics alone.
This approach may be considered when:
- Neurologic function is normal
- The abscess is relatively limited
- The organism has been identified
- The patient can be monitored closely
- There is no significant spinal instability
- There is no rapid clinical deterioration
Nonsurgical management requires careful follow-up because neurologic decline can occur even after treatment has started.
When Is Surgery Recommended?
Surgery is more likely to be recommended when there is:
- Progressive weakness
- Spinal cord compression
- Cauda equina compression
- Significant neurologic deficit
- Large abscess
- Progressive infection
- Failure of antibiotics
- Uncertain diagnosis
- Spinal instability
- Associated vertebral destruction
Rapidly worsening neurologic symptoms may require urgent surgery.
Surgical Decompression
The goal of surgery is to:
- Drain infected material
- Relieve pressure on the spinal cord or nerves
- Obtain cultures
- Remove infected tissue when necessary
- Preserve or restore spinal stability
A laminectomy may be performed to reach the epidural space.
The exact operation depends on the location and extent of the abscess.
Does Every Epidural Abscess Require a Laminectomy?
No.
The surgical approach depends on where the abscess is located.
An abscess behind the spinal cord may be accessed through a posterior decompression.
An abscess located in front of the spinal cord may require a different approach, particularly if there is significant associated vertebral or disc infection.
The operation is tailored to the anatomy of the infection.
Spinal Instability and Fusion
Some spinal epidural abscesses occur together with discitis and osteomyelitis.
If infection destroys enough bone or disc material, the spine may become unstable.
In these cases, treatment may require:
- Debridement
- Decompression
- Spinal instrumentation
- Fusion
- Corpectomy or vertebral reconstruction in severe cases
Spinal implants can be used when necessary to restore stability, even in the setting of infection.
Antibiotic Treatment
Antibiotics are required whether or not surgery is performed.
Treatment is tailored to:
- Culture results
- Organism sensitivity
- Location of infection
- Presence of osteomyelitis
- Response to treatment
Many patients require several weeks of antimicrobial therapy.
Some begin with intravenous treatment and later transition to oral medication.
Monitoring Recovery
Patients are followed with:
- Neurologic examinations
- Pain assessment
- CRP and ESR
- Blood cultures when appropriate
- Follow-up imaging when clinically indicated
Repeat MRI is not always necessary if the patient is improving clinically and laboratory markers are declining.
What Determines Neurologic Recovery?
Recovery depends on several factors, including:
- Severity of neurologic dysfunction before treatment
- Duration of spinal cord or nerve compression
- Speed of treatment
- Location of the abscess
- Overall health
Patients treated before major neurologic deficits develop generally have a better chance of preserving normal function.
Once severe spinal cord injury has occurred, recovery may be incomplete even after successful decompression and infection control.
Can a Spinal Epidural Abscess Come Back?
Recurrence is possible.
Risk may be increased when:
- The original source of infection is not controlled
- Antibiotic treatment is incomplete
- There is ongoing bacteremia
- Infected hardware remains problematic
- Discitis or osteomyelitis persists
- The patient remains immunocompromised
Follow-up is therefore important after treatment.
When Is a Spinal Epidural Abscess an Emergency?
Seek urgent medical evaluation for severe neck or back pain associated with:
- New weakness
- Rapidly worsening numbness
- Difficulty walking
- Loss of coordination
- Saddle anesthesia
- Urinary retention
- Loss of bowel or bladder control
- Fever with severe spinal pain
- Rapid neurologic deterioration
These symptoms may indicate significant spinal cord or cauda equina compression.
Outlook
A spinal epidural abscess is a serious but treatable infection.
Some patients can be managed with antibiotics and close observation. Others require urgent surgical drainage and decompression.
The most important factors guiding treatment are:
- Neurologic function
- Degree of spinal cord or nerve compression
- Size and location of the abscess
- Presence of discitis or osteomyelitis
- Spinal stability
- Response to antibiotics
The goals of treatment are to:
- Eliminate the infection
- Relieve pressure on the spinal cord or nerves
- Preserve neurologic function
- Maintain spinal stability
- Prevent recurrence
Early recognition and treatment are especially important when neurologic symptoms are developing.
Related Topics
- Spinal Infections
- Osteomyelitis & Discitis
- Post-Operative Spinal Infection
- Paraspinal Infection
- Facet Joint Infection
- Spinal Cord Compression
- Cauda Equina Syndrome
- Spinal Decompression
- Spinal Fusion