Intervertebral Disc Infection: Discitis and How it Affects Children
Discitis is more common in children than adults
Discitis, or disc space infection, is an inflammation of the intervertebral disc—the "cushion" in between the vertebrae (bones) of your spine. This rare disease, which impacts 1 out of every 100,000 people, can occur in adults but is more common in children.
Causes of Childhood Discitis
There are two recognized causes of discitis:
- From a previous surgical or diagnostic procedure (if a needle or other device transfers the infection).
- Spontaneous discitis; an infection that developed from a bacterial or viral organism that traveled to the disc by blood from another area of the body.
When the infection begins elsewhere and travels to the disc, it is called transient bacteremia. Ear infections and skin infections are two examples of infections that could lead to transient bacteremia and possibly discitis.
Once the disc becomes infected, it's difficult for the body to fight the infection. The disc is the largest organ in the body that doesn’t have its own blood supply (avascular). That's why the discs have to get their nutrition and blood supply—including white blood cells to fight infection—from diffusion through the vertebral end plates. Because discs essentially use a third party to fight infection as opposed to having the resources to do so themselves, they have a harder time warding off infection.
Symptoms of Discitis in Children
Symptoms usually first appear around age 7, and the most common symptom of discitis is severe back pain. However, it can be difficult to diagnose discitis because back pain may not be limited to one region of the spine; it's just general (or, as doctors say, "non-specific") back pain.
A possible sign of discitis in children is if a child refuses to walk or stand up. The infection can make it very painful to walk or stand, so some children simply avoid those activities.
Some children adjust their posture to avoid painful positions. For example, very young children who can’t yet speak may not seem to be in pain, but they may refuse to bend forward.
Even though discitis is an infection, that doesn't necessarily mean the child will have a fever. It is a possible symptom, though.
Diagnosing Discitis in Youngsters
Discitis can be difficult to diagnose. Even blood work—generally a good indicator of infection—isn't always helpful. However, children with discitis may have a higher white blood cell count, and they may have a higher erythrocyte sedimentation rate. The erythrocyte sedimentation rate is a specific test that looks at how fast red blood cells fall to the bottom of a tube. The faster they fall, the more likely it is there's inflammation somewhere in the body.
Magnetic resonance imaging, or MRI, is a highly sensitive and powerful imaging tool. The MRI images capture the spine’s soft and hard tissues rendering pictures of the patient’s anatomy in great detail. An infection is an example of a soft growth. In some cases, a plain x-ray will detect loss of normal disc height, show shrinkage of a disc’s size or shape, and may reflect erosion of the vertebral bodies’ endplates—another sign of discitis.
Treating Discitis in Children
The body has its own treatment for discitis called autofusion. Over time, disc inflammation can cause the body to release chemicals that actually harm the surrounding soft tissues. Damaged tissue is then replaced by scar tissue, which is the body's attempt to heal and protect itself. That scar tissue can then harden and fuse the bones together—that's autofusion.
Autofusion essentially "cures" discitis by immobilizing the intervertebral disc that's causing pain. In other words, the new bone growth (the autofusion) removes motion at the painful spinal segment, and that may reduce pain.
In terms of medical treatments—not just the body's own treatment—the recommended treatment for children with discitis is wearing a spinal brace (not an easy thing for kids). The brace immobilizes the area and actually help the vertebrae fuse in a good position—a position that won't cause pain. The vertebrae will still fuse without the help of a cast, but the bones may be out of alignment, which will cause more pain.
Some patients—especially ones with an elevated white blood cell count—may need an antibiotic that is usually given intravenously. These antibiotics generally target Staphylococcus aureus because that is the most common type of infection found in children with discitis.
Fortunately, with rest and antibiotics, children can fully recover from discitis and return to their activities.