Disk hernia or protrusion as cause for low back pain?
When a client comes with severe low back pain, often x-ray or magnetic resonance imaging of the lumbar spine are performed. If these images reveal a protrusion or hernia of one of the lumbar disks, the common assumption is, that these anomalies are the cause of the back pain. Based on a simple and understandable explanatory theory ("protruding disk presses on spinal root of nerve, nerve then signals pain”) doctors, patients and physiotherapists have been eager to seek the causal agent in the disk positions of the lumbar spine. Yet in 1994 a study was published in the respectable 'New England Journal of Medicine' which questions that assumption.
Since the design and scientific rigor of this study were of high quality, it had a major impact on the medical community.
According to this study, healthy people (those without any back pain) tend to show just as much and as often ‘disk bulging’ and ‘disk protrusions’ as do those with back pain. The commonly assumed causal relationship between disk anomalies and back pain therefore appears as very questionable, at least in the vast majority of cases. Only the extremely rare situation of a total disk “extrusion” seems to be positively correlated with back pain. To quote from the summary of this paper“On MRI examination of the lumbar spine, many people without back pain have disk bulges or protrusions but not extrusions. Given the high prevalence of these findings and of back pain, the discovery by MRI of bulges or protrusions in people with low back pain may frequently be coincidental”.
You can find the original article at http://content.nejm.org/cgi/content/short/331/2/69
A similar conclusion can be drawn from a more recent study titled “The value of magnetic resonance imaging of the lumbar spine to predict low-back pain in asymptomatic subjects: a seven-year follow-up study”. Their conclusion: “The findings on magnetic resonance scans were not predictive of the development or duration of low-back pain. Individuals with the longest duration of low-back pain did not have the greatest degree of anatomical abnormality on the original, 1989 scans.” For the original paper click here.