There are two kinds of steroid injections used in spinal degenerative (wear and tear) problems. These are facet joint injections and epidural injections. Both involve injecting steroids (some might be familiar with the term "cortisone" or "cortisol" injections) into a specific area of the spine. Both can be used in any area of the spine (cervical, thoracic or lumbar), although the cervical (neck) and lumbar (lower back) are much more common.
How is a steroid injection performed?
Because of the need for accurate localisation of the injection, and of course the equally important need for strictly aseptic (sterile) conditions, all spinal injections are done in an operating theatre environment. This may actually be an operating theatre, or may be a specialist treatment room, set up to the same levels of sterility.
The procedure, whether facet joint or epidural injection, takes about 15 minutes and is done as a day case. Commonly you will be one of a number of people having the same or similar injections on the same day. This does mean that there will be a certain amount of waiting around, but you should be in and out of the hospital within 2 or 3 hours. During the procedure, you will be lying on your front, awake and the (small) needle used to deliver the steroids will be used with local anaesthetic to aim to make it a pain free procedure. A special sort of mobile x-ray machine (an image intensifier) is used to direct the needle into the correct position in the spine.
Whilst the procedure is very similar, the indication (reason) for facet joint and epidural injections are different. Facet joint injections are carried out for back pain, whilst epidural steroid injections are carried out to aim to relieve nerve root entrapment symptoms (most commonly arm or leg pain).
Facet joint injections
There are two facet joints at each level in the spine. Along with the disc joint they make up the 3 joints which allow movement of the spine. The logic behind facet joint injections is that these joints can become inflamed as part of wear and tear, and that this inflammation produces pain. Given that steroids are a powerful anti-inflammatory drug, it is argued that injecting steroids in to the facet joints might reduce inflammation and thereby reduce spinal pain (neck or back pain) depending where the injections are directed. It is important to note that there is some debate about the role of facet joint injections as a useful treatment for back pain, both in terms of whether they have been proven to be effective and for how long. The National Institute for Clinical Excellence (NICE) guidelines do not support their use for back pain, based on lack of clinical evidence. It is also true that some have found them of great benefit, and indeed maintained benefit in the longer term. However, success, both in terms of short and long term benefit, is by no means certain.
In this procedure, the steroids are injected into the spinal canal itself so that they can access the nerve root. Again the logic is to use the anti-inflammatory properties of steroids to reduce inflammation in and around the nerve roots to relieve the symptoms of nerve root pain. In the neck this means arm pain (brachialgia) and in the lumbar spine, leg pain (sciatica). An epidural steroid injection is therefore used as an alternative to surgery for nerve root pain. The success rate when compared with surgery is lower (about 50%) compared with 80% for surgery, but it is a day case procedure, requiring no time off work beyond the attendance on the day of the injection and with considerably lower risk of complications. It is important to understand that the aim is for permanent relief of the symptoms (arm or leg pain). Clearly if it was simply deferring the inevitable, namely an operation, then there would be very little reason for doing it. This is not the case, and in a good percentage of patients, the success is long term.