BACK-TERIA (bacteria) and low back pain - What's the Link? Part 1

In every day practice, there will always be a small proportion of patients who simply don’t respond to manual therapy (chiropractic and physiotherapy). There are many reasons for this. These may include:

• central sensitization
• a distorted body schema
• altered motor-sensory integration
• limbic vigilance and
• conditioned behaviours

I use many questionnaires, inventories and forms along with a comprehensive history analysis and examination to rule in or rule out these potential complicating factors that can bring about ongoing pain. However, what if there is something lurking behind these physiological states.

I am currently treating 5 clients who have previously undergone lumbar microdiscectomy. Indications previous to surgery were ongoing low back pain. These patients did enjoy relief after surgery within 3 months to 6 years, however following that timeframe, they had fallen victim to the pain game once again. This has brought about a challenge in being able to improve their pain scales and functional outcomes. Below are some graphics outlining the procedural sequence of this surgery:

Patients who have had a microdiscectomy performed, have reported temporary relief for a few months to a few years. Unfortunately after this interval of time, they become the victim to chronic ongoing back pain.

Lets all please remember that microdiscectomy is certainly not a fix to low back pain. All that microdiscectomy does is eradicate the causation of hard neurologic signs (weakness, tingling and numbness) by sectioning the herniated nuclear material to reduce mechanical deformation of neural tissue. Furthermore, nerve compression WITHOUT chemical inflammation does not cause low back pain. Finally, lumbar microdiscectomy does not alter signal changes within the vertebrae of the spine (Type 1 Modic changes - refer to left MRI scan below), which is shown to have a strong association with low back pain.

To summarise the essence of Modic changes, they are divided into 3 subtypes:

• Type 1 Modic changes in the vertebral body are characterized by an increased signal intensity on T2-weighted MRI sequences, representing oedema within the bone marrow. this area of increased fluid density within the marrow represents an increase in vascularized fibrous tissue and ‘fissuring or disruption in the adjacent endplates’. These areas have also shown increased levels of pro-inflammatory cytokines and increased levels of innervations. Such obvious reactivity around the endplate is highly uncommon in an asymptomatic population. Importantly, Type 1 changes appear dark of T1 images (which are biased towards fat-containing tissues).
• Type 2 Modic changes are characterized by an increased signal intensity on both T1-weighted and T2-weighted sequences. This represents a fatty degeneration within the bone marrow, as well as proliferation of granular tissue.
• Type 3 Modic changes are characterized by a decreased signal intensity on both T1-weighted and T2 weighted sequences which is thought to be due to bond marrow sclerosis.

If you found the above slightly complicated to understand, in essence, all you need to know is that patients expressing Type 1 Modic changes (see diagram below on the left) have increased inflammation at the bony cartilage endplate. These findings are more common in low back pain.

What are the symptom producing effects in those patients with chronic low back pain who present with Type 1 Modic changes?

• Reduced capacity for spontaneous resorption of disc protrusion.
• Poor prognosis of nerve root blocks.
• Segmental instability leading to internal disc disruption.

Clinical reasoning suggests that the ongoing pain could possibly be due to a non-sterile environment within the bony vertebra and intervertebral disc leading to chronic low-grade inflammation.

So what processes are driving these Type 1 Modic changes that are present in those with low back pain who may not have responded to microdiscectomy? Read Part 2 to find out!