Archive for August, 2011

Spine Infection

The organs, tissues and bones of the human body are susceptible to invasion by opportunistic pathogenic microorganisms. When this occurs, the result is very often an infection that may cause injury to the body part and progress to overt disease through cellular or toxic mechanisms. The most common cause of infection is the staphylococcus aureus bacteria, also known as mersa or staph. It can also be caused by streptococci bacteria, pseudomonas aeruginosa bacteria (“blue-green pus” bacteria), escherichia coli (E coli), viral-fungal-parasitic organisms and other pathogens (e.g., cysticercosis, listeria monocytogenes, toxoplasma gondii, brucellosis, etc.). In rare instances, in industrialized countries such as the United States, it may be caused by the mycobacteriumtuberculosis bacteria (sometimes seen in IV drug users). In some cases, the source of the infection can not be identified.

Infection of the spine, although rare relative to the incidence of infections in other parts of the body, is very deleterious and can lead to spinal instability and other serious problems. Spine infection is most commonly caused by staphylococcus aureus bacteria. The infection is classified by its location on or in the spine such as (1) infection of the intervertebral disc or disc space (discitis); (2) infection of the vertebral bones of the spinal column (osteomyelitis); or, (3) an infection of the tissue (dura) covering the spinal cord and spinal nerve roots (epidural abscess). In most cases, an individual will experience only one of these clinical entities. Some critically ill patients, however, will present with all three. Failure to accurately diagnose and properly treat spinal infections can lead to catastrophic neurologic damage, paraplegia, and death.

Q: How does infection begin in the spine?

A: Spinal infection can occur spontaneously in the spine. However, infection is usually transmitted to the spine from adjacent tissue or another part of the body through the blood stream (bacteremia or sepsis). Infection most often occurs in the lumbar region of the spine, followed by the thoracic spine and, to a much lesser extent, the cervical spine (found in IV drug users).

Q: Who is at risk for spinal infections?

A: Individuals at risk of spinal infection include the elderly, smokers, the obese, patients who are immunocompromised (e.g., patients who have received organ transplants), patients with significant health problems such as diabetes mellitus, cancer, malnutrition, urological infection, and patients with wound infections. Spine infections can also arise from trauma to the spine and is increasingly found in IV drug users and those with long-term use of steroids.

Any surgery on the human body holds the risk of infection. This includes spine surgery, especially where instrumentation is involved, or when there has been implant/instrumentation migration. In the case of implant/instrumentation migration another surgery is required to correct the situation. Failure to confirm the absence of other infection in the body prior to the surgery is also problematic.

Q: How is spine infection diagnosed?

A: Diagnosing the presence of spine infection can be challenging. One reason is that the symptoms of spine infection – pain, inflammation, weakness, neurological deficits, weight loss, etc. – often mimic other spine condition symptoms or system irregularities such as pancreatitis, meningitis, radiculitis, appendicitis as well as non-specific back pain. When this occurs, an accurate diagnosis may not be made for days, if not weeks or months. Misdiagnosed or late-diagnosed patients may experience unnecessary operations as surgeons attempt to control the suspected pathology.

Once spinal infection is suspected the physician will confirm the diagnosis with blood cultures (e.g., white blood count), erythrocyte sedimentation rates (ESR) and C-reactive protein (CRP)), imaging studies (MRI with contrast medium (e.g., Gadolinium) and X-ray), nuclear medicine scans (PET), and biopsy (usually image guided). These studies may be repeated to evaluate the success of treatment protocols.

Q: After spine infection is confirmed, what are the treatment options?

A: The objective of spine infection treatment is to cure the infection and limit the possibility of further damage.The actual treatment modality depends largely on the severity and duration of the infection and the identification of the micro-organism involved. Once the micro-organism has been identified, specific antibiotics can used be to eradicate the bacteria.

Treatment options include intravenous and oral antibiotics, or injection of antibiotics directly into the infected area. This is often accompanied by bed rest and/or bracing to limit spine movement. If the infection is severe or fails to respond to initial treatment, long-term intravenous antibiotic or antifungal therapy may be required. In this instance, extended hospitalization may be required.

Despite the use of various antibiotics and antifungal agents, the treatment of a spine abscess often requires surgery to reduce pressure on the spinal cord or drain and remove infected material. Surgery is also required when there is evidence of bone destruction, spinal instability, vertebral collapse, spinal deformity, cauda equina syndrome, or other signs of neurologic dysfunction.

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