Lower Back Pain Investigations
Some lower back pain investigations are commonly used in the management of lower back pain. Most people with lower back pain, very understandably, want to know what is causing it and hope that these tests will help them pin down the cause of their lower back problem and provide a diagnosis.
The most common of these lower back pain investigations include:
- X-Ray
- Magnetic Resonance Imaging also called MRI scans
X-Ray
X-Rays are very good at showing up bony problems; they are good for identifying fractures and dislocations. They are not good at identifying muscles and ligaments as these are not seen on X-ray. X-Rays are also not very good at showing discs, an X-ray will only show the space a disc occupies.Despite this X-Rays are very commonly used for lower back pain investigations.
MRI Scans
MRI scans work by placed the part to be imaged in a powerful, uniform magnetic field. This allows images in 'slices' to be viewed and gives a clearer idea of soft tissue structures such as discs, ligaments and the spinal cord and nerve roots. An example is shown below.
CT Scans
You may also have heard of Computed Axial Tomography also calledCAT or CT scan. A CT scan is a type of X-ray that allows a three dimensional image to be produced from large numbers of two dimensional images. It is mainly used to look at the brain, chest and abdomen and for complex fractures. It is rarely used in the UK for lower back pain investigations.
Functional MRI
This is a newer technology that lets us see what is happening inside the brain when the body is stimultaed in some way. it is used increasingly in research and is helping us understand a lot more about pain. An example of a study using Functinal MRI can be found on this page about faith and pain symptoms.
How do X-Rays and MRI scans help?
When someone has been diagnosed with simple lower back pain, lower back pain investigations such as X-rays and MRI scans often show very little wrong - aside from the usual changes of age that are very common and are not always associated with pain.
Here are some things we know about MRI scans and lower back pain:
1. The things most often seen are changes of age or degenerative changes; these are common findings even in quite young people. Disc bulges are another very common finding.
2. These findings are as common in people with no back pain as they are in people with back pain.
3. There is no relationship between the findings on MRI and either the likelihood that you will get back pain, the severity of your symptoms or the likely outcome following an episode of back pain.
4. MRI scans taken before someone had back pain and after they got it look exactly the same.
5. MRI can be helpful to identify problems that may need surgery e.g. disc bulges causing nerve root irritation.
In most guidelines for the management of Lower Back Pain, MRI is not recommended unless the diagnostic triage suggests serious spinal pathology or nerve root involvement (see reference 1 below) "Structural changes seen on MRI appear to be as common in asymptomatic individuals as in people with Lower Back Pain and are, therefore, considered of little value in either explaining the cause of pain or deciding the subsequent course of management" (1 )
If there is any doubt that you may have a serious problem or a nerve root irritation then an MRI may be helpful. You would need to discuss this with your healthcare provider who will help you make this decision.
This information may seem a bit surprising - we believe in the value of these lower back pain investigations and tests and trust that they will tell us valuable information - indeed - used appropriately they may be very helpful. In practice they should not be routinely performed for simple low back pain. An exception may be when someone is very worried that they have a serious back problem and an MRI may be reassuring to them.
The best way to diagnose simple lower back pain is by seeing a health care professional who will take a full history and examine you. The combination of these two things should be enough to allow an experienced clinician to make a diagnosis that you can trust. If there is any doubt that you may have more serious problems than further lower back pain investigations can then be arranged.
References
1.Kleinstck-Frank, Dvorak-Jiri, Mannion-Anne-F.
Are structural abnormalities on magnetic resonance imaging a contraindication to the successful conservative treatment of chronic non-specific low back pain?
Spine, 1 Sep 2006, vol. 31, no. 19, p. 2250-7
2.Carragee-Eugene, Alamin-Todd, Cheng-Ivan, Franklin-Thomas, van-den-Haak-Erica, Hurwitz-Eric. Are first-time episodes of serious LBP associated with new MRI findings? The spine journal: official journal of the North American Spine Society, Nov-Dec 2006 ,vol. 6, no. 6, p. 624-
Lower Back Pain Toolkit Home Page
Understand the difference between acute and chronic pain
02-Nov-2009
