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Friday, August 29, 2014

What is Discitis?


A Spinal Disc is our natural "cushion" or "shock absorber" between the Vertebrae. Discitis is a bacterial infection of the Spinal Disc.

Why do Discs get infected?

The spinal disc is a structure with very little blood supply. Most of the blood vessels are found on the outer layer of the disc (annulus fibrosus), but rarely deeper than that. The core of the disc (nucleus pulposus) usually does not have blood vessels at all. It is the largest such space in the human body without any blood vessels. This can lead to problems such as infection. Normally, blood vessels are useful in preventing or treating infections. The body uses blood vessels to send cells to treat or prevent infection. In the case of the spinal disc, not enough blood vessels are present to carry out this function. If bacteria enter the disc, they can often multiply and become a serious infection.

Who is at risk to develop Discitis?

The following are some risk factors to get discitis
  1. Diabetic patients with poor control
  2. Patients who had a disc injection (discogram)
  3. Patients who had disc surgery
  4. Patients who have an infected vertebrae
  5. Patients who have depression of their immune system
  6. Patients who have an infection of the spine from recent spine surgery
  7. Children under the age of 8. Some children get discitis for no particular reason other than perhaps having an immature immune system.
  8. Patients with a severe urinary tract infection (UTI) or respiratory infection.

What are some of the common symptoms of Discitis?

Patients often experience severe low-back pain and are often quite debilitated. Any activity involving the low-back can cause severe pain and spasticity.
Small children may refuse to walk or arch their backs. Here are some additional symptoms:
  1. Severe low-back pain
  2. Headaches
  3. Low-back Spasms
  4. Fevers, chills
  5. Sweating, especially night sweats
  6. Fatigue (malaise)
  7. Lack of appetite (anorexia)


How do Spine Specialists diagnose Discitis?

Spine specialists use information from the patient’s history, physical examination and special spine tests to make a diagnosis:
  1. History
A history of having severe low-back pain, fevers, chills and sweats is suggestive of discitis. Having an infection in another part of the body or recent spine surgery can make it more likely to have this diagnosis.

Physical Examination

Patients with discitis may appear ill in the later stage of the disease but may appear otherwise normal early on. Pain with pressure on the spine can be very severe, more so than one would expect compared to other spine conditions. Patients may also refuse to move and prefer to lie down to rest their spine. The vital signs may show a rapid pulse, fast breathing, as well as the presence of a fever.
Here are some of the examination points:
  1. Palpation (touch and pressure) of the spine
  2. Range of motion (mobility)
  3. Sensation testing in the legs
  4. Strength testing of the leg muscles (motor)
  5. Reflex testing of the legs
  6. Gait testing
  7. Kernig’s test
  8. Valsalva test
  9. Babinski sign

Spine images can often help make the diagnosis of a lumbar discitis.

a. X-Rays
Plain X-Rays may be normal unless the infection involves a vertebra next to the disc and begins a destructive process. Sometimes a small amount of air can be seen in the space occupied by the disc which could suggest infection.

b. MRI Scans

Sagittal Lumbar Color MRI Discitis
Color MRI of the Low Back (Lumbar Spine) showing Discitis (red arrow)

MRI scans with intravenous contrast (dye) are usually the study of choice. The disc will often change color and show swelling around it. If the infection has spread to the vertebrae, this can also be verified by the MRI scan. Sometimes an abscess (collection of bacteria) in a space next to the disc can be seen as well (epidural abscess).

c. CT scans
CT scans are not very good at showing the disc itself, but like plain X-Rays can show signs suggesting infection. They can show if the bone of the vertebrae next to the disc is infected.

d. Nuclear Bone scans
Bone scans can show discitis in a very obvious way, but are not typically the study of choice, since the details of the spinal anatomy cannot be seen clearly.

e. Biopsy
A biopsy of the disc can confirm the diagnosis and find the organism (bacteria). However this is not routinely done to avoid spreading the infection at the time of the needle placement or removal.

What is the treatment of Discitis?

  1. Non-Surgical
A. Antibiotics
The primary treatment of discitis is the use of intravenous antibiotics. Potent antibiotics are often given for long periods of time (up to 6 weeks or more).
B. Activity Restrictions
The patient’s overall activity is often restricted. However, some movement and frequent movement may have some benefit to allow the antibiotic to be more available to the disc. Here are some more non-surgical treatment options:
C. Medications
  1. Non-Steroidal Anti-Inflammatory Drugs (NSAIDS)
  2. Muscle Relaxants
  3. Pain Killers
  4. Nerve Pain Medications
  5. Antidepressants
D. Brace
A brace may help by adding stability to the spine and limit the painful motion at the infected segment of the spine.
E. Physical Therapy (PT)
PT can help keep the patient as mobile as possible to avoid loss of muscle mass. It may also be helpful to mobilize a patient.

Surgical Care
Surgery is rarely needed for Discitis. Exceptions are the presence of a severe involvement of the vertebrae next to the disc (osteomyelitis), potentially causing them to collapse. In this case the vertebrae may have to be partially removed and a metal cage inserted. This is called a Lumbar Vertebrectomy/Corpectomy.

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