Chronic persistent pain can arise from any one of a number of sources in the patients back or neck.
Often it may be possible to pinpoint this to one or more joints of the spine (these are called zygapophysial joints, or incorrectly, facet joints). THERE IS NO OTHER WAY TO DETERMINE THIS CONCLUSIVELY. The fine-needle injection provides useful information about potentially problematic joints that help to guide the treatment approach. The joint injection is used primarily for diagnostic purposes and is not therapeutic in nature. However, if the block is successful and it breaks the pain cycle, up to a third of people having the injection notice a useful reduction in the severity of pain for a period of days or weeks. Sometimes the pain disappears!
The procedure to identify such a joint is relatively simple and quite safe but does require the use of an x-ray machine to be able to localise the location of the fine nerves to the joint with accuracy and reliability. Pain arising from these joints cannot be diagnosed by any other means (including CT scan, MRI scan or bone scan). X-ray controlled diagnostic blocks are the only means available of identifying this source of pain leading to the possibility of therapeutic neurotomy.
Benefits: validating your pain experience, and being scientifically-diagnostic of your pain. Even finding out that your pain is NOT from those joints can be reassuring for you – something is healthy and functioning well in your area of pain which you can then encourage into better activity levels!
A minimum of two sessions of injections are usually required in a short series, in which local anaesthetic is used. The patient then keeps an 8-hour pain diary provided to report if they experienced any pain relief and if so, how long it lasted. We recommend a 2nd injection to make sure that that joint is a source of your pain.
Guided by a special manoeuvrable low-dose x-ray machine a fine needle is directed to the target point at 2 or 3 locations. Radiation exposure has been described as equivalent to a 1-hour plane flight.
It is important that patients understand no pain relief may come from the injection, but this is still useful information as it implies that that joint(s) is not the source of your pain and we should look at the next one.
What are the risks?
The procedure is very safe, although as with any injections, there is a very small risk of infection, bleeding or allergic reaction. There is some radiation exposure from the x-rays. The main side effect is some soft tissue soreness from the needles, but this usually wears off within hours. The procedure can be thought of as similar to a dental injection.
After the Procedure
Patients may experience some local soft tissue soreness from having had needles in the back or the neck. Simple analgesics or ice may be used for this soreness. Patients are encouraged to try and differentiate this pain from their normal underlying pain problem for which they had the injection.
Please carefully consider the relief or non-relief of the underlying pain and diligently complete the Pain Charts. Has some part of your pain completely gone, and if so for how long? This documentation is very important for discussions later on concerning the effectiveness of the injections.
If relief occurs you should carefully attempt to move into some activities of daily living that are normally restricted by pain, but within reasonable limits and record these movements and activities for future discussion.