Spinal infections are rarely seen. In some cases, an infection may develop in the spinal bones, cushions between the vertebrae (discs), sheath enveloping the spinal cord, or the space around the spinal cord. The cause of infection may be various bacteria or fungi.
Infections of the spine may result from a previous spinal surgery, or develop spontaneously in patients who carry some risk factors. Factors that create a tendency for infection include: poor nutritional status, immune system disorders, HIV infection, cancer, diabetes and obesity. Also, in developing countries, patients who consume unpasteurized milk or dairy products are under risk for infections caused by the brucella bacteria.
Factors specific for surgery include long operative time (length of surgery), use of instrumentation, and revision surgery. Even in hospitals with optimum conditions, especially when instrumentation is used, infection rates may rise up to 4 percent despite all precautions. Repeat operations in the same area may further increase the risk. Most surgical infections occur between three days and three months after surgery.
How Does Spinal Infection Develop?
Infection is caused by microorganisms in the vertebrae, which may be borne by blood or direct inoculation during surgery. Microorgansisms cause inflammation at the local tissue.
Later infection spreads to the discs and bone and cause destruction in these structures.
Finally, infection penetrates the bone and spread to the spinal canal, compressing the nerves.
At this stage, vertebra may collapse.
What are Symptoms of Spinal Infection?
The findings of infection may be fever, fatigue, headache, neck stiffness, and local signs including swelling, tenderness, redness, drainage, or pain in the operative field. In some cases, the patient may experience numbness in the arms and legs, loss of sensation, decrease in muscle strength. The development of these symptoms may be subtle in some patients, or severe from the beginning in others.
How are Spinal Infections Diagnosed?
Diagnosis begins with documenting the patient's history and making a physical examination. Your doctor will ask you some questions to diagnose spinal infections. If your doctor suspects an infection after listening to you and examining you, he will ask you to undergo some tests. These tests may include various imaging methods (direct X-rays, CT, MRI, and scintigraphy).
Then, your doctor may order some tests that may reveal the presence of infection, such as complete blood count, CRP, or sedimentation rate. The test results may be elevated after surgery in the absence of an infection, however levels frequently return to normal within a few weeks. Eleveted levels of these tests long after surgery or in patients who did not undergo surgery may indicate an infection.
Other laboratory tests include blood cultures, tissue samples harvested from the infection site, or cultures of fluids draining from the infection site. These tests show definitive evidence on the presence of infection and the organism causing it. The biopsy is often performed under local anesthesia and under fluoroscopic (an imaging device) guidance.
In addition to the above, serologic blood tests for Brucella (common in Turkey), PCR for tuberculosis, and skin sensitivity tests (PPD) for tuberculosis may be performed.
Nonsurgical Treatment of Spinal Infections
Nonsurgical treatment includes antibiotic treatment, antituberculosis treatment, and antifungal treatment for fungus infection. The type and duration of treatment differs according to the causative microorganism.
Antibiotics and antifungals are given through the veins or the mouth. Antibiotic treatment through the veins will be applied in the hospital. Alternatively, by inserting a catheter, this treatment can be applied at home with the help of a health care worker. The treatment may be as short as 7-10 days or long as 6-12 weeks. In some conditions, your doctor may recommend brace (corset) treatment to alleviate the pain and rest your spine.
When is Surgical Treatment Necessary?
- Surgery may be necessary in the following situations:
- Patients with large abscesses that cannot be cured with antibiotic treatment
- The presence of abnormal movement due to destruction in the vertebra
- Deformity (slipping of the vertebra, bending to one side, gibbosity), and presence of intense pain due to these.
In addition, spinal cord compression due to abscess, fracture or gibbosity, and the subsequent nerve injury (loss of strength, severe numbness) requires urgent surgery. In these patients, the pressure on the spinal cord must be relieved using surgery.
What are Surgical Options?
There are various surgical alternatives. The surgical procedure depends on the type of infection, location, size of the abscess, destruction caused by infection, and the immune status of the patient. The simplest is drainage of the abscess and removal of infected tissues (debridement). In some occasions, cages and instrumentation may be needed to replace the destructed vertebras (figure 5).
Figure 5. Operation for infection includes removal of all the infected structures followed by reconstruction of the spinal column by placement of titanium mesh cages and fixation by posterior instrumentation and fusion. There are several other ways of surgical procedures as alternatives to this procedure for the treatment of infection.
In some cases, following the procedure, a drain will be left inside. In other instances, the wound will be left open for periodic cleaning or the application of negative pressure dressings (wound vac) that will allow constant drainage of the wound site.
What are Long-term Effects?
The treatment may be long, especially in severe and widespread infections. Following surgical treatment performed in the hospital, a long period of antibiotic treatment— either thorough the veins or mouth—is continued. Your doctor will control white blood cell counts, CRP levels and sedimentation rates, and end treatment after resolution of symptoms and normalization of blood values.