Herniated or Slipped Disks, Back Pain, and Bacteria
Bacteria in Herniated Disks
A herniated disk in the spine is often a painful condition. Physical therapy and anti-inflammatory medicines frequently reduce the pain and help the body to heal itself. Sometimes the pain persists, however, and the problem becomes chronic. In this situation spinal surgery may be recommended.
Researchers from the University of Southern Denmark have made an exciting discovery which suggests that surgery could sometimes be avoided. The scientists have found bacterial infections in some herniated disks. They believe that 20% to 40% of chronic back pain cases associated with a herniation are produced by a bacterial infection. The scientists also say that antibiotics can reduce the pain.
The research has created a great deal of interest amongst spinal surgeons. A leading surgeon in the UK has said that the Danish discovery is so important that the researchers deserve a Nobel Prize. Other spine doctors are more cautious in their evaluation of the research and say that talk about a Nobel Prize is far too premature. Many doctors and scientists say that the research results are promising but that further investigations are needed.
The Human Vertebral Column or Backbone
What is a Spinal or Intervertebral Disk (or Disc)?
Disks are short, cartilaginous cylinders that are located between the vertebrae, or bones, of the spine. The disks absorb shock created by movements such as running and jumping and also prevent the vertebrae from grinding against each other and breaking down.
Parts of a Spinal Disk
- The annulus fibrosis is the tough and fibrous outer surface of the disk.
- The nucleus pulposus is the gelatinous inner portion of the disk.
- The nucleus pulposus is made of loosely arranged fibres in a gel made of molecules called mucoproteins.
- Mucoproteins consist of both protein and a type of carbohydrate called a glycosaminoglycan. Glycosaminoglycans make liquids viscous.
Structure of a Cervical Vertebra in the Neck
What Is a Herniated Disk?
Most back pain is often due to arthritis or a problem with back muscles, ligaments (which attach bones to one another), or tendons (which attach muscles to bones). A doctor's diagnosis is needed to confirm that a back problem is actually due to a herniated disk.
Herniated disks are also known as slipped, ruptured, or prolapsed disks. A slipped disk hasn't moved out of place, despite its name. Instead, the outer layer of the disk has ruptured, allowing the softer inner tissue to bulge outwards. A prolapse is a condition in which an entire organ moves out of place. The term "herniated disk" is probably the best one in reference to the spine because it's the most accurate. A hernia is a condition in which part of an organ protrudes through the structure that encloses it.
The body attempts to heal the broken surface of a disk and remove the expelled material. Before the area is repaired, however, the person may be in pain. The pain arises due to the inner tissue of the disk pressing on a spinal nerve and irritating it.
Herniated disks are most common in middle-aged people. Being overweight increases the risk of a disk rupture. A sudden strain or repetitive activities may be the immediate cause of the injury, however.
Symptoms of a Herniated Disk
Some people have no symptoms from a herniated disk. The rupture may be small or may not affect a nerve. In other people there may be pain for a while, but the pain disappears as the body repairs the rupture and breaks down the material that was released from the disk. The healing process may take weeks or even months, however. Unfortunately, some people experience chronic (long-term) pain from a herniated disk.
Herniated disks most often occur in the lower back but may also appear in the neck. The nerve irritation caused by the hernia can produce pain, numbness, and tingling. There may also be weakness in the muscles controlled by the affected nerves.
If a disk in the neck is herniated, the pain usually appears in a shoulder and arm. If the damaged disk is in the lower back, the person generally feels pain in their buttocks, thigh, and leg. Sometimes pain will appear in the foot, too. If the pressure on a nerve in the lower back is intense, the person may lose control of urination or defecation. These conditions are medical emergencies and require immediate attention. Coughing, sneezing, laughing, urinating, and defecating can all increase the pain from a herniated disk.
Anyone with chronic back pain should visit a doctor for a diagnosis and treatment recommendations.
What Happens During a Disk Herniation?
Bacteria and Chronic Back Pain
The research done so far suggests that in order for an intervertebral disk to be infected by bacteria it must first rupture. The rupture causes the initial pain when the contents of the disk affect a nerve. The Danish researchers say that as the body heals the injury, blood vessels extend into the disk. Bacteria in the blood can therefore enter the disk, where they multiply and cause an infection. Inflammation, swelling, and tiny fissures have been observed in the bones of the vertebrae around herniated disks. The investigators believe that bacterial infections cause these conditions.
One treatment for a herniated disk that's causing continuous problems is to surgically remove the displaced tissue. The Danish researchers examined the spinal tissue taken from people who had undergone surgery for chronic back pain. They followed "stringent antiseptic sterile protocols" to avoid contamination of the samples with bacteria from another source. The researchers found that nearly half of the samples were infected by bacteria. In addition, they discovered that more than eighty percent of the infected samples contained a bacterium called Propionibacterium acnes—the same bacterium that is involved in acne.
Propionibacterium acnes normally lives on our skin, in our mouths, and in our large intestine. It can also enter our blood. The researchers think that the bacterium travels to damaged spinal disks in the bloodstream and then releases chemicals that trigger inflammation.
A Herniated, Ruptured, or Slipped Disk: An Animation
Using Antibiotics to Treat Chronic Back Pain
In another experiment, the Danish researchers gave antibiotics to people who had suffered from back pain for at least six months and had evidence of spinal disk damage and vertebral swelling around the damage. (The subjects weren't tested for the presence of bacteria in their spine.) Other people with these same conditions were given a placebo.
Antibiotic treatment for 100 days reduced pain and other problematic conditions significantly in people given an antibiotic compared to those given a placebo. The increased benefits were still present and in some cases had even improved one year after the initial evaluation.
It's important to note that the people in the test had specific problems in their spine. Antibiotics haven't yet been tested on other people with back pain. In addition, since the overuse of antibiotics has led to frightening resistance to the medications in bacteria, it's vital that antibiotics aren't prescribed for back pain patients "just in case" they help them.
Some Possible Problems in Disk Research
Research involving humans is often difficult because so many factors are involved. For example, bacteria are tiny and ubiquitous creatures and often appear where they're not wanted. Very careful procedures are needed to prevent contamination of a tissue sample when the sample is extracted or examined.
Good experiments use a placebo. A placebo is a harmless substance that has no medical benefit when administered to a patient. Some subjects in an experiment are given a placebo and some are given the test treatment. The subjects don't know which type of treatment they are receiving. This procedure enables the researchers to take the "placebo effect" into account when analyzing the results of the experiment. Sometimes knowing that something may help us enables us to feel better, even when the treatment has no known benefit.
All experiments involving humans need to be double blind. A double blind experiment is one in which neither the subjects nor the person administering a treatment know its identity. Unfortunately, the Danish antibiotic experiment may not have been completely double blind. Some of the subjects that were given antibiotics may have suspected that they had received a medication because they experienced diarrhea as a side effect of the treatment. This suspicion may have affected the outcome of the experiment.
As strong as this research is, it is not definitive.— NHS (National Health Service)
Further Research Is Needed
While the results of the Danish investigations are very interesting and have impressed many people, they don't prove that bacteria contribute to the pain of herniated disks. Just because bacteria are present in an area of the body that is experiencing problems doesn't necessarily mean that the bacteria are causing the problems. In addition, some scientists have suggested that the antibiotic treatment decreased pain because it reduced inflammation and not because it killed bacteria.
The Danish research was reported in 2013. Since that time, other researchers have found bacteria in herniated disk material. In 2015, a group of Australian doctors and researchers analyzed the scientific literature with respect to the possible link between bacteria in herniated disks and chronic pain. They found that bacteria are commonly detected in herniated disks. They say that at the moment there is "modest" evidence supporting the idea that the bacteria are responsible for a patient's pain. They also say that further research is needed to demonstrate that the bacteria that have been discovered are not the result of tissue contamination.
Many scientists seem to have an attitude of cautious optimism with respect to the idea that bacteria can cause back pain. They are intrigued by the research but want to see the results of more investigations. They say that not only should more research be done but also that more patients should be involved in the studies. In the future, however, doctors may have another treatment to offer some people who are suffering from long-term back pain due to a herniated disk.
Herniated disk facts from the U.S. National Library of Medicine
Antibiotics may help ease chronic back pain (An analysis of the Danish research published by the National Health Service)
Low back pain and bacterial infection information from Medscape (A summary and analysis of the Danish research with links to the scientific papers.)
An analysis of research linking bacteria to herniated disk pain published by the NIH (National Institutes of Health)
Questions & Answers
© 2013 Linda Crampton