Spinal osteomyelitis and discitis are infections involving the bones and discs of the spine.
Osteomyelitis refers to infection of the vertebral bone.
Discitis refers to infection of the intervertebral disc.
Because the disc and the adjacent vertebral endplates are closely connected, these infections commonly occur together and are often called discitis-osteomyelitis or vertebral osteomyelitis.
The infection can occur in the cervical, thoracic, or lumbar spine. The lumbar spine is affected most often.
Most cases can be successfully treated with antibiotics, but surgery may be necessary when infection causes spinal instability, deformity, abscess formation, spinal cord or nerve compression, or failure of medical treatment.
What Causes Spinal Osteomyelitis and Discitis?
In many cases, bacteria reach the spine through the bloodstream from an infection somewhere else in the body.
Possible sources include:
- Skin infections
- Urinary tract infections
- Bloodstream infections
- Infected intravenous catheters
- Heart valve infections
- Recent surgery
- Spinal injections or procedures
- Intravenous drug use
In some patients, no clear source is ever identified.
Spinal infection may also occur after spine surgery or another invasive procedure involving the spine.
What Organisms Cause Spinal Infection?
The most common causes are bacteria.
Staphylococcus aureus is one of the most frequent organisms responsible for vertebral osteomyelitis.
Other bacteria and, less commonly, fungal organisms can also cause spinal infection.
Determining the responsible organism is important because it allows antibiotic treatment to be specifically targeted.
Symptoms
The most common symptom is persistent neck or back pain.
The pain may be:
- Severe
- Constant
- Worse with movement
- Present at rest
- Worse at night
- Slowly progressive
Other symptoms can include:
- Muscle spasms
- Fever
- Chills
- Fatigue
- Loss of appetite
- Difficulty standing or walking
- Arm or leg pain
- Numbness or weakness
Importantly, many patients with spinal osteomyelitis or discitis do not have a fever.
Persistent or progressively worsening spinal pain may therefore be the main symptom.
Why Can Osteomyelitis and Discitis Become Serious?
The vertebral bodies provide structural support for the spine.
As infection damages the disc and adjacent vertebrae, the bone can progressively weaken.
This may lead to:
- Vertebral collapse
- Spinal instability
- Kyphosis or other deformity
- Epidural abscess
- Paraspinal abscess
- Spinal cord compression
- Nerve root compression
In severe cases, the infection can destroy enough bone that the spine can no longer maintain normal alignment.
Spinal Epidural Abscess
Infection may spread from the disc or vertebral body into the spinal canal.
This can produce a spinal epidural abscess, which is a collection of infected material outside the dura surrounding the spinal cord or nerves.
An epidural abscess may compress:
- The spinal cord in the cervical or thoracic spine
- The cauda equina or nerve roots in the lumbar spine
Progressive neurologic compression can become an emergency.
Paraspinal and Psoas Abscess
Infection can also spread outside the spinal column into the surrounding muscles.
This may produce:
- Paraspinal abscess
- Psoas abscess
- Other deep soft-tissue infections
These collections may sometimes be drained with an image-guided catheter.
Larger or more complicated abscesses may require surgery.
Who Is at Risk?
Spinal osteomyelitis can occur in otherwise healthy patients, but risk is increased by:
- Diabetes
- Immunosuppression
- Chronic kidney disease
- Cancer
- Intravenous drug use
- Recent bloodstream infection
- Recent spine surgery
- Spinal injections
- Long-term intravenous catheters
- Older age
A spinal infection should still be considered even when none of these risk factors are present.
How Is Spinal Osteomyelitis Diagnosed?
Diagnosis usually involves a combination of examination, blood testing, and imaging.
Blood Tests
Laboratory testing may include:
- Complete blood count
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR)
- Blood cultures
CRP and ESR are commonly elevated during spinal infection and may be followed over time to determine whether treatment is working.
A normal white blood cell count does not rule out spinal infection.
MRI
MRI with contrast is generally the most important imaging study when discitis or osteomyelitis is suspected.
MRI can identify:
- Disc infection
- Vertebral osteomyelitis
- Endplate destruction
- Epidural abscess
- Paraspinal infection
- Spinal cord compression
- Nerve compression
MRI can also help determine how far the infection has spread.
CT Scan
CT provides more detailed information about the bones of the spine.
It can help evaluate:
- Vertebral destruction
- Endplate erosion
- Bone collapse
- Spinal alignment
- Surgical anatomy
CT may also be used to guide a biopsy.
Biopsy
Whenever possible, identifying the organism responsible for the infection helps guide treatment.
Blood cultures may identify the bacteria without the need for another procedure.
If blood cultures are negative, a CT-guided biopsy may be performed.
A needle is placed into the affected disc or vertebral body, and a sample is sent for:
- Bacterial culture
- Fungal culture when appropriate
- Pathology
- Other specialized testing
In a stable patient, antibiotics may sometimes be delayed until cultures are obtained so that the responsible organism can be identified more accurately.
Antibiotic Treatment
Antibiotics are the foundation of treatment for most spinal infections.
The medication is selected based on:
- Culture results
- Suspected organism
- Antibiotic sensitivities
- Patient allergies
- Kidney function
- Severity of infection
Treatment commonly lasts several weeks.
Some patients initially receive intravenous antibiotics and later transition to oral medication.
The exact duration depends on the organism, severity of infection, and response to treatment.
Monitoring Treatment
Patients are usually followed clinically and with laboratory testing.
Doctors may monitor:
- Pain
- Neurologic function
- CRP
- ESR
- Blood cultures when necessary
Repeat MRI is not always required if symptoms and laboratory values are improving.
MRI abnormalities can persist for some time even after the infection is successfully controlled.
Is a Brace Necessary?
A brace may sometimes be used when infection has weakened the vertebrae.
Bracing can:
- Reduce painful spinal movement
- Provide temporary support
- Help patients remain mobile
However, a brace cannot correct major spinal instability or progressive vertebral destruction.
The decision to use one depends on the affected spinal level, degree of bone destruction, alignment, and symptoms.
When Is Surgery Needed?
Many patients can be treated successfully without surgery.
Surgery is more likely to be recommended when there is:
- Progressive neurologic weakness
- Spinal cord compression
- Cauda equina compression
- Large epidural abscess
- Significant spinal instability
- Progressive vertebral collapse
- Severe or progressive deformity
- Persistent severe pain despite appropriate treatment
- Failure of infection to respond to antibiotics
- Large abscess requiring drainage
- Uncertain diagnosis requiring tissue sampling
The specific procedure depends on the location and extent of infection.
Surgical Debridement
Debridement means removing infected, damaged, or nonviable tissue.
This may include removal of:
- Infected disc material
- Damaged bone
- Epidural abscess
- Infected soft tissue
The goal is to reduce the burden of infection and relieve pressure on neurologic structures.
Spinal Decompression
When infection causes spinal cord, cauda equina, or nerve compression, surgical decompression may be required.
Procedures may include:
- Laminectomy
- Abscess evacuation
- Removal of infected tissue
- More extensive decompression when necessary
Decompression alone may not be sufficient if the infection has also made the spine unstable.
Spinal Fusion During Infection
Spinal infection can destroy the vertebral bodies and discs enough to create instability.
In these cases, spinal fusion and instrumentation may be necessary even while the infection is active.
Screws, rods, cages, or other implants may be used to stabilize and reconstruct the spine.
This may seem unusual because implants are being placed near an infected area. However, a severely unstable spine may not heal or function properly without mechanical stabilization.
Treatment may therefore combine:
- Removal of infected tissue
- Decompression
- Spinal reconstruction
- Instrumentation and fusion
- Targeted antibiotics
Corpectomy and Reconstruction
Severe osteomyelitis can destroy a large portion of a vertebral body.
A corpectomy may be required when there is:
- Extensive vertebral destruction
- Severe spinal instability
- Progressive deformity
- Significant compression from infected bone
- Failure of less extensive treatment
During a corpectomy, part or most of the damaged vertebral body is removed.
The spine may then be reconstructed using a cage or structural graft combined with spinal instrumentation.
Cervical Osteomyelitis and Discitis
Infection in the cervical spine can be particularly important because even a relatively small epidural abscess or deformity may compress the spinal cord.
Symptoms may include:
- Neck pain
- Arm pain
- Hand numbness or weakness
- Difficulty walking
- Loss of balance
Progressive spinal cord dysfunction requires prompt evaluation.
Thoracic Osteomyelitis and Discitis
Thoracic infection may cause:
- Mid-back pain
- Pain around the chest or ribs
- Leg weakness
- Leg numbness
- Difficulty walking
- Balance problems
Because the spinal cord passes through the thoracic spine, epidural infection or vertebral collapse can cause thoracic myelopathy.
Lumbar Osteomyelitis and Discitis
Lumbar infection is particularly common.
Symptoms may include:
- Severe low-back pain
- Leg pain
- Numbness
- Weakness
- Difficulty standing or walking
Severe infection may compress the cauda equina and cause bowel or bladder dysfunction.
Post-Operative Discitis and Osteomyelitis
Discitis or osteomyelitis can occasionally occur after spine surgery.
Symptoms may include:
- Increasing pain after an initial period of improvement
- Persistent or worsening back pain
- Fever
- Wound drainage
- Elevated inflammatory markers
The infection may involve a disc space, vertebrae, instrumentation, or several structures at the same time.
Treatment may require antibiotics, surgical debridement, or both.
When Is Spinal Infection an Emergency?
Seek urgent medical evaluation when severe neck or back pain is associated with:
- New or progressive weakness
- Difficulty walking
- Rapidly worsening numbness
- Loss of coordination
- Saddle numbness
- Urinary retention
- Loss of bowel or bladder control
- Fever with severe spinal pain
These symptoms may indicate epidural abscess, spinal cord compression, or cauda equina compression.
Recovery
Recovery varies significantly depending on:
- Extent of infection
- Organism involved
- Amount of vertebral destruction
- Presence of an abscess
- Neurologic function
- Need for surgery
- Overall health
Pain may improve gradually over several weeks as the infection is controlled.
When substantial bone destruction has occurred, recovery can take longer.
Patients may require physical therapy to restore:
- Walking
- Strength
- Balance
- Endurance
- Normal activity
Outlook
Spinal osteomyelitis and discitis are potentially serious infections, but most can be successfully treated when identified and managed appropriately.
Many patients recover with antibiotics alone.
Surgery may be necessary when infection causes spinal instability, progressive deformity, abscess formation, neurologic compression, or failure of medical treatment.
The goals of treatment are to:
- Eliminate the infection
- Protect the spinal cord and nerves
- Maintain or restore spinal stability
- Prevent progressive deformity
- Preserve neurologic function
- Return the patient to normal activity whenever possible
Treatment should be individualized based on the location and severity of infection, culture results, neurologic examination, degree of bone destruction, and mechanical stability of the spine.
Related Topics
- Spinal Infections
- Spinal Epidural Abscess
- Post-Operative Spinal Infection
- Paraspinal Abscess
- Facet Joint Infection
- Spinal Decompression
- Spinal Fusion
- Spinal Corpectomy