Vertebral osteomyelitis refers to an infection of the vertebral body in the spine. It is a fairly rare cause of back pain, especially in young healthy adults.

Generally, the infection is spread to the vertebral body by a vascular route. The veins in the lower spine (Batson’s plexus) drain the pelvis and provide for a direct route of entry for the bacteria to get into the spine. For this reason, there is a preponderance of infections in the spine that occur after a urologic procedure (e.g. cystoscopy).

Vertebral osteomyelitis may also be referred to as spinal osteomyelitis, or a spinal infection.

Common Causes of Osteomyelitis

Patients susceptible to osteomyelitis include:

• Elderly patients

• Intravenous drug users

• Individuals whose immune systems are compromised

Conditions that compromise the immune system include:

• Long-term systemic administration of steroids to treat conditions such as rheumatoid arthritis

• Insulin Dependent Diabetes Mellitus

• Organ transplant patients

• Acquired Immune Deficiency Syndrome (AIDS)

• Malnutrition

• Cancer

Symptoms

Symptoms of back pain due to a spinal infection often develop insidiously and over a long period of time.

In addition to back pain, which is present in over 90% of patients with vertebral osteomyelitis, general symptoms may include one or a combination of the following constitutional symptoms:

• Fever, chills, or shakes

• Unplanned weight loss

• Nighttime pain that is worse than daytime pain

• Swelling and possible warmth and redness around the infection site

The most common site of vertebral bone infection is in the lower back, or lumbar spine, followed by the thoracic (upper) spine, the cervical spine (neck). It may also develop in the sacrum, the bone at the very bottom of the spine that connects to the pelvis.

Diagnostic Studies

The process of diagnosing a spinal infection usually starts with an X-ray. X-rays will usually be normal in the first 2 to 4 weeks after the infection starts. For changes to show up on an X-ray, 50% to 60% of the bone in the vertebral body needs to be destroyed. If the disc space is involved (discitis), the disc space may narrow and destruction of the endplates around the disc may be seen on the X-ray.

The most sensitive and specific imaging study for spinal infection is an MRI scan with enhancement with an intravenous dye (Gadolinium). The infection will cause an increase in blood flow to the vertebral body, and this will be picked up by the Gadolinium, which will enhance the MRI signal in areas of increased blood flow.

Surgery

Surgery is sometimes necessary to obtain cultures for diagnosis of which type of bacteria are the cause of the infection. A biopsy may be obtained by needle biopsy, using a CT scan to visualize the needle and guide it into the infection. On occasion, open biopsy may also be necessary for diagnosis.

Treatment for vertebral osteomyelitis is usually conservative (meaning nonsurgical) and based primarily on use of intravenous antibiotic treatment. Occasionally, surgery may be necessary to alleviate pressure on the spinal nerves, clean out infected material, and/or stabilize the spine.

Surgical decompression is necessary if an epidural abscess places pressure on the neural elements. Because surgical decompression often destabilizes the spine further, instrumentation and fusion are also frequently included to prevent worsening deformity and pain.

Nonsurgical Treatments for Vertebral Osteomyelitis

Treatment for a spinal infection usually includes a combination of intravenous antibiotic therapy, bracing, and rest.

Most cases of vertebral osteomyelitis are caused by Staphylococcus Aureus, which is generally very sensitive to antibiotics. The intravenous antibiotic treatment usually takes about four weeks, and then is usually followed by about two weeks of oral antibiotics. For infection caused by tuberculosis, patients are often required to take three drugs for up to one year.

Bracing is recommended to provide stability for the spine while the infection is healing. It is usually continued for 6 to 12 weeks, until either a bony fusion is seen on X-ray, or until the patient’s pain subsides. A rigid brace works best and need only be worn when the patient is active.