Gut-disc axis: A cause of intervertebral disc degeneration and low back pain?

Purpose

Low back pain (LBP), a widely prevalent and costly disease around the world, is mainly caused by intervertebral disc (IVD) degeneration (IDD). Although numerous factors may trigger this degenerative process, microbiome dysbiosis has recently been implicated as one of the likely causes. However, the exact relationship between the microbiome and IDD is not well understood. This review summarizes the potential mechanisms and discusses microbiome dysbiosis’s possible influence on IDD and LBP.

Methods

Prospective literature review.

Results

Alterations in microbiome composition and host responses to the microbiota causing pathological bone development and involution, led to the concept of gut-bone marrow axis and gut-bone axis. Moreover, the concept of the gut-disc axis was also proposed to explain the microbiome’s role in IDD and LBP. According to the existing evidence, the microbiome could be an important factor for inducing and aggravating IDD through changing or regulating the outside and inside microenvironment of the IVD. Three potential mechanisms by which the gut microbiota can induce IVD and cause LBP are: (1) translocation of the bacteria across the gut epithelial barrier and into the IVD, (2) regulation of the mucosal and systemic immune system, and (3) regulation of nutrient absorption and metabolites formation at the gut epithelium and its diffusion into the IVD. Furthermore, to investigate whether IVD is initiated by pathogenic bacteria and establish the correlation between the presence of certain microbial groups with the disease in question, microbiome diversity analysis based on16S rRNA data can be used to characterise stool/blood microbiota from IVD patients.

Conclusion

Future studies on microbiome, fungi and viruses in IDD is necessary to revolutionize our thinking about their possible role in the development of IVD diseases. Furthermore, we believe that inflammation inhibition and interruption of amplification of cascade reaction in IVD by targeting the gut and IVD microbiome is worthwhile for the treatment of IDD and LBP.

Level of Evidence I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

     

Low back pain: how does your physical therapist treat low back pain?

Low back pain is so common that 8 of 10 people experience it at some time in their lives. Although the pain in your back may be severe, most low back pain is not due to a serious problem. There are many risk factors that increase the chances of getting low back pain. As we get older, we often feel more back pain due to weakened muscles and stiffening joints. New clinical practice guidelines for the treatment of low back pain were published in the April 2012 issue of JOSPT. The guidelines describe ways to treat back pain based on best research evidence.     

Intervertebral disc a source of pain? Low back pain: problems and future directions--case reports

OBJECTIVE: The objective of this article is to provide evidence supporting the idea that intervertebral disc is a source of low back pain. SUMMARY OF BACKGROUND DATA: Diagnostic tests currently available for diagnosis of a painful disc are inadequate. Treatment protocols for low back pain generally ignore the presence of a painful disc. Pathological processes that may be responsible for discogenic pain are incompletely understood. Without diagnosis and treatment, disc disruption evolves to advanced stages of spinal dysfunction. New treatment modalities are becoming available which if applied early may stop disc disruption. CASE REPORTS: We describe here two case reports where discogenic nature of patients' symptoms was suspected based on patients' history, MRI findings and discography. We highlight the inadequacies of spinal imaging and discography in detecting at painful disc. A treatment (Intradiscal electrothermal therapy) was then directed exclusively to the intervertebral discs. We provide arguments that link discal therapy to resolution of patients' symptoms. Resolution of patients' symptoms after the discal treatment raised our suspicion that pain emanated from the intervertebral discs. CONCLUSIONS: Intervertebral disc is a source of low back pain that is often ignored. No diagnostic test currently exists that can reliably confirm presence of a painful disc. Early diagnosis and treatment of a painful disc may reduce enormous pain and suffering from low back pain.     

How is recovery from low back pain measured? A systematic review of the literature

Recovery is commonly used as an outcome measure in low back pain (LBP) research. There is, however, no accepted definition of what recovery involves or guidance as to how it should be measured. The objective of the study was designed to appraise the LBP literature from the last 10 years to review the methods used to measure recovery. The research design includes electronic searches of Medline, EMBASE, CINAHL, Cochrane database of clinical trials and PEDro from the beginning of 1999 to December 2008. All prospective studies of subjects with non-specific LBP that measured recovery as an outcome were included. The way in which recovery was measured was extracted and categorised according to the domain used to assess recovery. Eighty-two included studies used 66 different measures of recovery. Fifty-nine of the measures did not appear in more than one study. Seventeen measures used pain as a proxy for recovery, seven used disability or function and seventeen were based on a combination of two or more constructs. There were nine single-item recovery rating scales. Eleven studies used a global change scale that included an anchor of ‘completely recovered’. Three measures used return to work as the recovery criterion, two used time to insurance claim closure and six used physical performance. In conclusion, almost every study that measured recovery from LBP in the last 10 years did so differently. This lack of consistency makes interpretation and comparison of the LBP literature problematic. It is likely that the failure to use a standardised measure of recovery is due to the absence of an established definition, and highlights the need for such a definition in back pain research.     

Do number of days with low back pain and patterns of episodes of pain have similar outcomes in a biopsychosocial prediction model?

Purposes

We used two different methods to classify low back pain (LBP) in the general population (1) to assess the overlapping of individuals within the different subgroups in those two classifications, (2) to explore if the associations between LBP and some selected bio-psychosocial factors are similar, regardless which of the two classifications is used.

Method

During 1 year, 49- or 50-year-old people from the Danish general population were sent fortnightly automated text messages (SMS-Track) asking them if they had any LBP in the past fortnight. Responses for the whole year were then classified into two different ways: (1) In relation to the number of days with LBP in the preceding year (0, 1–30, and >30), (2) In relation to the frequency and duration of episodes of LBP (more or less never pain, episodic, and more or less constant pain). Some bio-psychosocial factors, collected with a questionnaire at baseline 9 years earlier, were entered into regression models to investigate their associations with the subgroups of the two classifications of LBP and the results compared.

Results

The percentage of agreement between categories of the two classification systems was above 68 % (Kappa 0.7). Despite the large overlap of persons in the two classification groups, the patterns of associations with the two types of LBP definitions were different in the two classification groups. However, none of the estimates were significantly different when the variables were compared across the two classifications.

Conclusion

Different classification systems of LBP are capable of bringing forth different findings. This may help explain the lack of consistency between studies on risk factors of LBP.

     

Outcome assessment in low back pain: how low can you go?

The present study examined the psychometric characteristics of a core-set of six individual questions (on pain, function, symptom-specific well-being, work disability, social disability and satisfaction) for use in low back pain (LBP) outcome assessment. A questionnaire booklet was administered to 277 German-speaking LBP patients with a range of common diagnoses, before and 6 months after surgical (N=187) or conservative (N=90) treatment. The core-set items were embedded in the booklet alongside validated reference questionnaires: Likert scales for back/leg pain; Roland and Morris disability scale; WHO Quality of Life scale; Psychological General Well-Being Index. A further 45 patients with chronic LBP completed the booklet twice in 1–2 weeks. The minimal reliability (similar to Cronbachs alpha) for each core item was 0.42–0.78, increasing to 0.84 for a composite index score comprising all items plus an additional question on general well-being (quality of life). Floor or ceiling effects of 20–50% were observed for some items before surgery (function, symptom-specific well-being) and some items after it (disability, function). The intraclass correlation coefficient (ICC) (test–retest reliability) was moderate to excellent (ICC, 0.67–0.95) for the individual core items and excellent (ICC, 0.91) for the composite index score. With the exception of symptom-specific well-being, the correlations between each core item and its corresponding reference questionnaire (validity) were between 0.61 and 0.79. Both the composite index and the individual items differentiated (P<0.001) between the severity of the back problem in surgical and conservative patients (validity). The composite index score had an effect size (sensitivity to change) of 0.95, which was larger than most of the reference questionnaires (0.47–1.01); for individual core items, the effect sizes were 0.52–0.87. The core items provide a simple, practical, reliable, valid and sensitive assessment of outcome in LBP patients. We recommend the widespread and consistent use of the core-set items and their composite score index to promote standardisation of outcome measurements in clinical trials, multicentre studies, routine quality management and surgical registry systems.     

Do functional tests predict low back pain?

STUDY DESIGN: A cohort of 307 nonsymptomatic workers and another cohort of 123 workers with previous episodes of low back pain were followed up for 2 years. The outcomes were measured by symptoms, medical consultations, and sick leaves due to low back disorders. OBJECTIVES: To study the predictive value of a set of tests measuring the physical performance of the back in a working population. The hypothesis was that subjects with poor functional capacity are liable to back disorders. SUMMARY OF BACKGROUND DATA: Reduced functional performance has been associated with back pain. There are few data to show whether reduced functional capacity is a cause or a consequence of pain. METHODS: Mobility of the trunk in forward and side bending, maximal isokinetic trunk extension, flexion and lifting strength, and static endurance of back extension were measured. Standing balance and foot reaction time were recorded with a force plate. Clinical tests for the provocation of back or leg pain were performed. Gender, workload, age, and anthropometrics were managed as potential confounders in the analysis. RESULTS: Marked overlapping was seen in the measures of the subjects with different outcomes. Among the nonsymptomatic subjects, low performance in tests of mobility and standing balance was associated with future back disorders. Among workers with previous episodes of back pain, low isokinetic extension strength, poor standing balance, and positive clinical signs predicted future pain. CONCLUSIONS: Some associations were found between the functional tests and future low back pain. The wide variation in the results questions the value of the tests in health examinations (e.g., in screening or surveillance of low back disorders).     

Does unspecific low back pain really exist?

Only 20 % of low back pain or sciatica is of a specific origin. These specific pain conditions include tumours, spondylitis, rheumatic and metabolic diseases as well as radicular syndromes. By far the most pain from discs, facet and sacroiliac joints, ligaments and muscles must be considered as unspecific, because no anamnestic information or clinical signs exist (radiological changes included) to assign pain to structural or functional correlates. In addition, the therapeutic consequences from the assignment of structural changes to pain remain unclear. In acute pain situations the specificity of the pain is not important because of the fast relief of the disease, in chronic pain situations, fear avoidance beliefs and pain behaviour seem to be much more important than structural and functional changes.