A Discogram is a diagnostic procedure applied to examaine to structure and intergrity of and intervertebral discs.
Quick Anatomy
The spine is constructed of 33 vertebrae, 24 of which are deemed moveable. Between each of these moveable levels is an intervertebral disc, responsible for supplying shock absorptive properties to the area and providing sufficient intervertebral space for the associated facet j0ints at the back. Disc degeneration is a very common contributing factor in disc pain however this is also extremely common in non painful disc as well. Unfortunately the two don’t always go hand in hand so when we identify degenerate discs on tests such as MRI scans, this isn’t always conclusive. In these situations, it is sometimes beneficial to test more specifically the discs that are suspected to play a role in your pain. Ultimately this enables us to formulate the best treatment scenarios that are available to you as an individual.
What Happens?
During this diagnostic test you will to be conscious enabling you to communicate with the anaesthetist, however a sedatory drug that makes you feel very groggy and relaxed will be given beforehand. To test a lumbar disc you will need to lie on your tummy, allowing access to the appropriate section of the spine. A needle, guided by image intensifiers (small X-Ray machine) is then inseted in to the targeted disc, and a volume of saline and dye mix injected. The saline increases the pressure within the disc and if this recreates your pain then we can surmise that this is your ‘pain generator’. The dye that is contained within the injection also allows the structure of the disc to be visualised on the image intensifier allowing further analysis. It used to be common practice for more than one level to be tested to allow the anesthetist to find a control (a non pain generator) for comparison however we now tend to test only the suspected levels.
Once the pain genrator(s) have been positively located, a small amount of local aneasthetic and steroid are injected to help settle the disc down with the aim of reducing your pain. This procedure IS NOT CURATIVE AND SHOULD NOT BE CONSIDERED A LONG TERM SOLUTION IN ISOLATION. This procedure is undertaken as part of a larger rehabiliation regime. The most commonly accepted preventative treatment in conservative management is exercise therapy. When pain is above a certain threshold it will have an inhibitive effect on muscle function. In simple terms, the muscle that you are trying to build may be in varying states of spasm making this both painful and difficult. The discogram basically alleviates this pain giving you a window of opportunity to work on this muscle strength and function.
The following animation gives an excellent account of the procedure and is well worth viewing to bring the information together.
This procedure is a little like Marmite in the medical world, that is they either love it or hate it! The last decade has brought about huge changes in the practice of medicine placing research as the basis of all treatment guidelines. Whilst this should always be encouraged, we appear to be fast approaching the fine line that divides evidence based practice from clinician experience and autonomy. There are currently three main points that are causing this divide.
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The first is that despite the successful location of the pain generating disc, not everyone gets satisfactory pain relief following the anaesthetic/steroid injection The main answer to this appears to lie in patient selection. Research has demonstreated that the presence of a particular type of inflammatory degeneration (type 1 and 2 modic) seen on MRI to the ‘end plates’ of the disc, seem to greatly improve the level of relief experienced. (1,2 - there are multiple papers regardin this however this review sums it up well)
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Secondly is that the procedure provides no long term benefit to the patient and this has been shown through research (3 - one example of multiple papers). The main issue with this research is that most of the discograms are given in isolation as a sole intervention. Many surgeons and anesthetists would agree that this is not a successful treatment per se but what is does allow is temporary pain relief to enable exercise rehablitation. Exercise rehabilitation is a long standing and well reseached treatment for Low Back Pain but unfortunately pain can, and will, inhibit local muscles from functioning correctly. When viewed from this standpoint, the discogram is a diagnostic ‘enabler‘, not a treatment!
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Thirdly, recent research has provided evidence that discograms have the affinity to increase the occurence of future prolapes (4). For this reason the need to obtain a non-pain generator or control is seen as less important, and one is guided more by the analysis of the MRI and individual symptoms. This therefore minimises the risk of future prolapses at previously non symtomatic levels.
For those of you who feel you have a little more tollerence to medical terminolgy and would like to learn a bit more about this procedure the following link is useful article. It would not be considered light reading however!
There is a procedural booklet available under the education drop down menu for those of you undergoing a discogram. You will need ‘pdf’ software (acrobat etc) to be able to view this.
Refs
Please be aware that there are many more articles regarding this topic than listed below however this is purposely kept short to maintain simplicity.
1) Fayad F, Lefevre-Colau MM, Rannou F, Quintero N, Nys A, Mace Y, Poiraudeau S, Luc Drape J, Revel M. Relation of Inflammatory Modic Changes to Intradiscal Steroid Injection Outcome in Chronic Low Back Pain. Spine J 2007; 16(7): 925-31
2) Muzin S, Isaac Z, Walker J. The Role of Intradiscal Steroids in the Treatment of Discogenic Low Back Pain. Curr Rev Musculoskelet Med 2008; 1: 103-7
3) Khot A, Bowditch M, Powell J, Sharp S. The use of Intradiscal Steroid Therapy for Lumbar Spinal Discogenic Pain - A randomized Controlled Trial. Spine 2004; 29(8): 833-7
4) Carragee EJ, Don AS, Hurwitz EL, Cuellar JM, Carrino J, Herzog R. 2009 ISSLS Prize Winner: Does Discography Cause Progression of Degeneration Changes in the Lumbar Disc - A Ten-Year Matched Cohort Study. Spine 2009; 34(21): 2338-45
