Osteomyelitis and discitis are infections of the spine. These diseases are rare, but can lead to serious and permanent neurological injuries, including severe pain, paralysis or difficulties walking. Osteomyelitis and discitis generally attack the vertebrae in the spine and the cushions between our vertebrae known as discs. However, an infection in the spine can have devastating consequences not only for the vertebrae and discs, but also surrounding tissues and the spinal cord. Still, if the diagnosis of osteomyelitis or discitis is made soon enough after the infection reaches the spine, a patient can make a good recovery.
What causes a spine infection?
An infection in the spine usually starts outside the spine. Discitis and osteomyelitis are typically caused when infection enters the bloodstream from a location of the body distant from the spine. The infection spreads to the spine through the bloodstream. The source of infection can be as simple as a cut on the finger or an infected tooth. Infections can also be introduced into the spine through medical procedures involving the spine, such as steroid injections commonly used to treat herniated discs or spinal arthritis.
How should a spinal infection be diagnosed?
Unfortunately, the diagnosis of discitis or osteomyelitis is often delayed by health care providers. The diagnosis is often missed or delayed because the primary symptom of discitis and osteomyelitis is the very non-specific complaint of back pain. Not only is back pain an extremely common patient complaint, back pain can arise from many different causes, the most common of which is changes in the spine related to the normal aging process.
Because back pain is such a common complaint, it is important for doctors and hospitals to consider a patient’s whole picture including their age, symptoms and prior medical and surgical history. At the very least, doctors should raise a red flag when their patient complains of fever associated with the recent onset of severe back pain that started without any obvious cause like trauma or unusual strain on the back.
Doctors must also consider whether a patient has certain risk factors for developing osteomyelitis or discitis. Any condition or disease which weakens a patient’s immune system can raise the likelihood of the patient developing vertebral osteomyelitis or discitis. The diagnoses may be more likely if the patient’s medical or surgical history includes any of the following:
- Infection of the heart muscle or valves
- History of spinal surgery or Invasive spinal procedure (e.g. epidural steroid injection)
- Infection of catheters placed in the arteries or veins
- IV Drug Use
Just as important in the diagnosis of discitis and osteomyelitis are the results of vital signs, physical exam and tests. The physical examination and testing are essential to help a physician narrow the possible causes of back pain. One warning sign is severe pain and tenderness at a specific point in the spine. Occasionally, severe back pain associated with discitis and osteomyelitis is focal, meaning it is in an isolated area of the spine, typically the lower back. When performing an examination of the patient, doctors should not only ask the patient where they hurt, but should use their fingers to percuss (tap) the spine to try to determine whether the pain is worsened.
Neurologic examination of the patient’s legs is another important part of the physical examination for potential vertebral osteomyelitis or discitis. A patient with an infection in their vertebrae or disc spaces may develop weakness or sensory changes in their legs. The infection can also affect the nerves which allow the patient to control urination and bowel movement. A patient who complains of the inability to feel the act of urination, or control bladder or bowel movements, should raise a red flag for the diagnosis of compression of the spinal cord or nerve roots within the spine. Such compression is typically caused by a mass of infectious debris known as an epidural abscess.
The results of certain laboratory testing can point toward a possible diagnosis of vertebral osteomyelitis or discitis. Urine or blood cultures are often positive for bacteria in patients with spinal infection. Lab tests should be performed on blood specimens. These tests can demonstrate whether an infection is present.
Radiologic imaging can be the key to confirming a diagnosis of osteomyelitis or discitis. Unfortunately, plain x-rays are typically negative in the early phases of a spinal infection. Physicians should consider ordering more sensitive radiology tests such as an MRI or CT scan as part of the work-up for unexplained, severe back pain. Unfortunately, doctors often hesitate to order these more expensive radiology tests until the patient has attempted a course of conservative treatment of back pain with drugs, steroid injections, or physical therapy. As a result, the diagnosis of osteomyelitis and discitis may be delayed until a time after the patient has suffered permanent injury to their spine, spinal cord or nerves.
How are spinal infections treated?
Infections of the spine are potentially life altering, but they are also very treatable. Generally, the earlier the diagnosis, the better odds for a good outcome.
Intravenous antibiotics are the mainstay of treatment for vertebral osteomyelitis or discitis. Ideally, the patient will see a specialist in infectious disease medicine who can determine the IV antibiotic regimen which will have the best chances of fighting the infection. Treating physicians may also recommend a procedure known as a CT guided needle biopsy. In a CT guided needle biopsy, a physician inserts a needle into the patient’s back or neck at the suspected site of infection and removes a sample of infected fluid from a site of infection. A CT guided biopsy, along with laboratory testing, can help to identify the specific type of germ which needs to be treated. Once the correct germ is identified, treating doctors can refer to clinical practice guidelines developed by the Infectious Diseases Society of America. These guidelines help physicians choose the best antibiotic to treat a patient’s infection.
Vertebral osteomyelitis or discitis can have devastating consequences, even when the diagnosis is made in a timely manner and the patient receives the appropriate treatment to fight the infection. Yet time is still of the essence. A delay in diagnosis of a spinal infection, or a delay in treating the infection, can leave a patient disabled or dependent on care providers or assistive devices around the home for the rest of their life. Such delays can rob people of their independence.
1 McDonald, M., Spelman, D., (2019), Vertebral Osteomyelitis and Discitis in Adults. In E. Baron (Ed.), UpToDate. Retrieved July 7, 2019 from https://www.uptodate.com/contents/vertebral-osteomyelitis-and-discitis-in-adults