Low Back Pain, Modic Changes and Bacterial Infections

Modic changes are edema in the vertebral body, which can only be detected on magnetic resonance imaging (MRI) and are closely associated with low back pain. There is growing evidence their formation may be related to bacterial infection. Herniated discs may be susceptible to bacterial infection and these infections may cause Modic changes. In patients with Modic changes antibiotic treatment appears to reduce symptom severity, although alternative methods of treatment could be considered.

In alternative medicine fungal infections have been linked with everything from allergies to arthritis (Kauffman 2000). In addition, Kauffman as well as others link chronic pain to fungal infections although there is no clear mechanism described. Albert et al (2008) published a hypothesis linking Modic changes to either mechanical causes or bacterial infection.

A mechanical cause: Degeneration of the disc causes loss of soft nuclear material, reduced disc height and hydrostatic pressure, which increases the shear forces on the endplates and micro fractures may occur. The observed Modic change could represent oedema secondary to the fracture and subsequent inflammation, or a result of an inflammatory process from a toxic stimulus from the nucleus pulposus that seeps through the fractures.

A bacterial cause: Following a tear in the outer fibres of the annulus e.g. disc herniation, new capilarisation and inflammation develop around the extruded nuclear material. Through this tissue it is possible for anaerobic

bacteria to enter the anaerobic disc and in this environment cause a slowly developing low virulent infection. The Modic change could be the visible signs of the inflammation and oedema surrounding this infection, because the anaerobic bacteria cannot thrive in the highly aerobic environment of the Modic change type 1 (Albert et al 2008).

There is empirical evidence to support this view. Sterling et al (2001) found that nucleus pulposus material removed during surgery from herniated contained the bacteria Proprionibacterium acnes and Cornybacterium propinquum in 53% of cases. Similarly Corsia et al (2003) found that 71% of the 30 herniated discs they studied from different subjects had a bacterial infection. In the cervical spine they found 59% of herniated discs were infected with Staphylococcus being more prominent than proprionibacterium in their study. A follow up study by Sterling and Jiggins (2002) found the nucleus pulposus was infected in 31% of subjects with lumbar disc herniation and 0% in subjects with other spinal disorders such as tumor, scoliosis and fracture. This lends further support to Albert et al’s (2008) hypothesis.

To date no work has shown these bacterial infections cause Modic changes but treatment with antibiotics has been shown to improve function and decrease pain in patients with Modic changes. Albert et al (2013) found 100 days of Bioclavid, an Amoxicillin based antiobiotic produced improved low back pain, leg pain and function compared with placebo. Interestingly the results continued to improve after the course of antibiotics at 6-month and 1 year follow up. Antibiotics can have an anti-inflammatory effect in their own right. However, Albert et al used Bioclavid as it has one of the weakest anti-inflammatory effects. Furthermore, anti-inflammatory medications usually don’t produce a lasting, let a lone improving effect and as such this mechanism of action seems unlikely.

Tentatively it’s possible to hypothesise this continued improvement may be due to repair of Modic changes. This however, is highly speculative. Due to the nature of the study we do not know what percentage of patients had infected discs, if the antibiotics eliminated the bacteria if present, and whether there was any alteration in Modic changes at 1-year follow up. Nonetheless, this is highly thought provoking work.

So how do we implement these findings? Certainly we need to consider a potential bacterial cause in our patients with Modic changes. However, assessing a possible infection is difficult and impractical. At this point it is hard to know if there are any symptoms associated with these bacterial infections that could help with diagnosis.

Given the results of Albert et al (2013) in stubborn cases of low back pain with Modic changes that do not respond to mechanical treatment, bacterial based treatment may be considered. In the first instance anti-bacterial agents such as Uva Ursi or Berberine could be utilised in concert with a diet containing the phenols in nuts, seeds, vegetables and some herbs, as well as garlic and ginger. In addition, probiotics and prebiotics could be added to hypothetically promote competition with the potential unwanted bacteria. After a trial period of 3 months if no progress is made antibiotic treatment would be the logical step.

In patients with Modic changes bacterial infection of herniated intervertebral discs should be considered. Antibiotic treatment has been found to reduce back and leg pain, and improve function in patients with Modic changes with low back pain. Thus in patients with Modic changes on MRI not responding to a mechanical approach antibacterial nutritional therapy could be considered.