What is Vertebral Osteomyelitis?
Vertebral osteomyelitis, also known as spinal osteomyelitis or spondylodiskitis, is a type of bone infection in the spine. It’s pretty rare, making up only 3% to 5% of all bone infections each year. Often, the symptoms are not specific to this disease, which means it can sometimes take several months to diagnose properly.
The goal of this explanation is to highlight the main features, tests, and treatments for vertebral osteomyelitis, to help you get a fast diagnosis and treatment. Spotting this condition quickly is important, as it can prevent additional health issues and increase your chances of recovery.
Vertebral osteomyelitis can occur after an injury to the spine, surgery, or it can spread from an infection in a nearby part of the body. If it’s not treated, this infection can seriously harm your health, causing changes to the shape of the spine, paralysis, and in extreme cases, it can even be deadly.
What Causes Vertebral Osteomyelitis?
Vertebral osteomyelitis is most often caused by one type of germ or bacteria. The most common one is Staphylococcus aureus, especially if it spreads through the bloodstream. This means that if someone had an infection with this bacteria in their blood within the last three months and displays matching spine MRI findings, doctors would typically suspect vertebral osteomyelitis. In this case, they may not even need to take a sample of fluid from the disc space in the spine to confirm the diagnosis.
In contrast, other kinds of bacteria like coagulase-negative staphylococci and Propionibacterium acnes are typically found in spinal infections after surgery, particularly when spinal fixation devices have been used.
The particular bacteria causing vertebral osteomyelitis may differ in certain areas where specific diseases are common, or in patients with weakened immune systems. Examples of localized bacteria include Mycobacterium tuberculosis and Brucella. Another type of bacteria, the Mycobacterium avium complex, is common in patients with HIV. Fungal vertebral osteomyelitis is rarely seen but can occur in certain areas, among people with weak immune systems and in those who use intravenous (IV) drugs or have intravenous catheters. Famous examples of these fungi are histoplasmosis and blastomycosis.
There are several risk factors that increase the chances of getting vertebral osteomyelitis, including old age, having a weak immune system, diabetes, long-term use of corticosteroids, cancer, malnutrition, and intravenous drug use.
Risk Factors and Frequency for Vertebral Osteomyelitis
Vertebral osteomyelitis, a type of bone infection, is more common in some areas and populations than others. In the United States, there are about 4.8 cases for every 100,000 people, and this number has been growing in recent years. Around the world, the rate varies from 1 to 7 cases per 100,000 people depending on the country. It tends to occur more often as people age and is slightly more common in males than females.
- The average rate of vertebral osteomyelitis in the U.S. is around 4.8 cases per 100,000 people.
- The incidence of this disease has been on the rise over the past few decades.
- Globally, the rate of vertebral osteomyelitis can range from 1 to 7 cases per 100,000 depending on the country.
- The chance of getting this disease increases with age.
- It is slightly more prevalent in males than females.
Mortality rates from vertebral osteomyelitis also vary significantly depending on factors like location, the bacteria causing the infection, and whether the patients are high-risk or low-risk. In some cases, the mortality rate can be as high as 11% after one year. Before antibiotics were in use, more than 25% of patients could die from this disease.
Signs and Symptoms of Vertebral Osteomyelitis
When a patient first shows signs of vertebral osteomyelitis (an infection in the vertebrae of the spine), the symptoms can be pretty vague, especially in the early stages. The most common symptom is back pain, but not all patients will have a fever (this only happens in around 35-60% of cases). Initially, the pain might be quite mild, or seem to be coming from all over, rather than one specific place. However, as the disease gets worse, the pain usually starts to focus in around the spine area that’s affected. The lower back is the most likely place to be affected, followed by the mid-back and then the neck. Surprisingly, in most cases, pressing on the spine where it’s tender doesn’t always cause pain. Also, about a third of patients may experience neurological issues, like loss of sensation, weakness, or radiating pain along the nerve pathways (radiculopathy).
- Common symptom: Back pain
- Non-specific early symptoms
- Fever is present in 35%-60% of cases
- Pain usually localizes to the affected area as the disease progresses
- Most common areas affected: Lower back, mid-back, and neck
- Spine tenderness is not always present
- About a third of patients have neurological symptoms like sensory loss, weakness or radiculopathy
Testing for Vertebral Osteomyelitis
The range of conditions that can cause back pain is extensive and can include degenerative disc disease, fractures in the vertebrae, or muscle spasms. Fever doesn’t necessarily narrow down these options, as it may be a symptom of numerous conditions, including viral sickness, infections in deep layers of the skin at the back, or a bone infection in the spine. Vague symptoms, a broad range of possible conditions, and a non-specific physical examination can potentially delay the diagnosis.
A complete blood count (CBC), which measures the cells that make up your blood, is a useful starting point when looking into the cause of back pain accompanied by fever. However, in the case of a bone infection in the spine, this test is not very effective. Your neutrophil (a type of white blood cell that fights infection) count often remains normal, and a significant number of patients with this infection have a normal white blood cell count. Comparatively, tests for the levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) have been found to be very accurate in diagnosing a spinal bone infection and are therefore more useful. They measure inflammation in your body and can also help track how well your treatment is working. It is also recommended to have blood cultures (tests to detect bacteria or fungi in your blood) done if you have fever and back pain.
Specific tests for bacterial infections like Brucella sb and M. tuberculosis, as well as fungal infections, should be carried out depending on the geographical region one resides in and their overall health condition. These tests are especially beneficial for those with weakened immune systems or living in areas where such infections are common.
Alongside lab tests, imaging techniques play a crucial role in diagnosing a spinal bone infection. Though X-rays are often the first step due to their availability and speed, they are not very effective in detecting this infection. In contrast, Magnetic Resonance Imaging (MRI), which uses a magnetic field and radio waves to create detailed pictures of your body, is the preferred method because of its high accuracy. MRIs can identify multiple common features in patients with vertebral osteomyelitis – one being that infections in the disc space between vertebrae quickly spreads to the adjacent bone regions. Also, in most cases, there will be swelling of soft tissue or an abscess (pus-filled cavity) in the spaces near the spine.
Computed Tomography (CT), which uses X-rays and a computer to create detailed images of your body, can also be useful, though it’s frequently less effective than an MRI. CT might detect subtle erosion of the bone or an abscess in the tissue. Still, it may underestimate the extent of the infection in its early stages or in severe cases. In situations where MRIs are not an option, specific Nuclear Medicine imaging techniques like Gallium-67 single-photon emission computed tomography (SPECT) can be a reliable alternative.
When the imaging results suggest a spinal bone infection, but the blood cultures are negative, a biopsy or aspiration (removal of fluid or tissue) is the recommended course to identify the organism causing the infection before starting antibiotic therapy. CT is usually the best modality to guide this procedure, with MRI or nuclear medicine studies helping in choosing the site for the CT-guided biopsy or aspiration.
Treatment Options for Vertebral Osteomyelitis
Vertebral osteomyelitis, or infection of the spine, is usually treated using antibiotics. The specific type of antibiotics used can vary and may include both types that are given by injection and types that are taken by mouth, depending on the particular type of bacteria causing the infection. Most experts advise a six-week course of antibiotics. A longer treatment period is not usually more effective for typical cases.
Surgery is rarely needed for vertebral osteomyelitis. It is only considered in situations where the infection has reached the point where it is threatening the nerves, causing a high degree of bone damage leading to instability in the spine, leading to the formation of large pockets of pus (epidural abscesses), causing unmanageable back pain, or when the infection isn’t improving with medication.
In the past, there was concern that doing surgery could increase the risk of the infection persisting or coming back. However, recent studies suggest that surgery does not increase the likelihood of undesirable health outcomes in patients with known or suspected vertebral osteomyelitis.
Commonly, a brace is used to provide stability to the spine while it heals. After treatment, the patient will need to have regular imaging tests, like MRI or CT scans, to make sure that the infection is healing correctly. Rehabilitation exercises to restore muscle strength are recommended as part of the recovery process.
What else can Vertebral Osteomyelitis be?
There are a number of conditions that may share some common symptoms and can be confused for each other. These include:
- Chronic non-bacterial osteomyelitis – a long-term bone inflammation not caused by bacteria
- Ewing sarcoma – a rare type of cancer that affects the bones or the tissue around the bones
- Gout – a type of arthritis that causes painful inflammation in one or more joints
- Gaucher disease – a rare genetic disorder that affects many of the body’s organs and tissues
- Malignancy – another term for cancer that occurs when cells in the body begin to grow out of control
- Pseudogout – a type of arthritis that causes pain, stiffness, tenderness, redness, warmth, and swelling in some joints
- Septic arthritis – an infection in a joint that causes pain and swelling
- Sickle cell anemia – a severe hereditary form of anemia where a mutated form of hemoglobin distorts the red blood cells into a crescent shape at low oxygen levels
- Vitamin C deficiency – lack of sufficient vitamin C in the body
- Vertebral compression fracture – a collapse of a vertebra in the spine
- Vaso-occlusive pain episode – a common painful complication of sickle cell anemia
These conditions need to be carefully differentiated based on specific symptoms and diagnostic tests to ensure correct treatment.
What to expect with Vertebral Osteomyelitis
Vertebral osteomyelitis, an infection in the bones of the spine, often requires a long recovery period, even with treatment. In some cases, multiple procedures may be necessary. Like all surgeries, these procedures carry significant risks, including potential paralysis.
Unfortunately, at least 15% of patients dealing with this condition may experience permanent nerve damage. This typically results in ongoing disability and can significantly impact the patient’s quality of life, often leading to a poorer overall life experience.
Possible Complications When Diagnosed with Vertebral Osteomyelitis
Potential Risks:
- Recurring infections
- Broken bones
- Paralysis or loss of muscle function
- Long-term damage to the nervous system
- Constant pain
- Disability or loss of ability to function as usual
Preventing Vertebral Osteomyelitis
If you have vertebral osteomyelitis, which is an infection in the spine, it’s essential to understand what the future may look like in terms of your condition. Your doctor will explain why it is important to take your medication as prescribed and talk about what could happen if you don’t follow the recommended treatment. It’s really important for you to keep regular appointments with your doctor and go for immediate medical attention if your symptoms get worse while you are receiving treatment.
