Spinal injections explained

Spinal injections may be used in many cases of chronic back pain, both to find out what is causing the pain and also to treat the pain. These two separate uses of spinal injections are referred to as diagnostic and therapeutic. If an injection provides pain relief in the area that is injected, it is likely that this particular area is the source of the problem. Injections are also therapeutic in that they can provide temporary relief from pain.

This article on spinal injections is written by Andrew Quaile, Consultant Spinal and Orthopaedic Surgeon, Hampshire and Surrey.

Injections around the spine have a number of uses. In the main, they are used to provide control of symptoms whilst the condition treated goes on to natural resolution or to get intrusive symptoms under control to allow physical therapy to progress. In other words, they are creating a ‘window of opportunity’ for therapies which otherwise would create too much discomfort to proceed.

The other main use would be in turning off symptoms for a temporary time period allowing an understanding of the pain generator. These injections are done under x-ray control and therefore it is possible to identify the painful structure. The third use of injections is to deliberately stimulate a source of pain to again identify a pain generator. The injection technique used most frequently for nerve pain is an epidural.

This differs from the one given in pregnancy as it contains hydrocortisone as well as local anaesthetic. The hydrocortisone is there as a treating agent to reduce inflammation caused by mechanical irritation of a nerve as well as chemical and cellular irritation. It can be administered by the traditional injection in the back or by a lower injection in the sacrum, or tailbone. That route is called a caudal. Epidurals can be performed in the cervical or thoracic spine by appropriately trained specialists.

Further common injections for nerve pain consist of nerve root blocks. These are targeted injections for individual nerves and need to be directed under x-ray control.

They are more specific than epidurals and therefore can also be used to identify a pain source.

Injections for back pain tend to be non-specific injections such as trigger point injections into painful knots of muscle and connective tissue or targeted injections into facet joints under x-ray control.

The facet joints are paired joints at each level of the lumbar spine. They classically give symptoms of stiffness in the morning and after prolonged sitting as the WD40 in the joints dries out with a lack of movement and activity tends to lubricate the joints again. Injections provide that window of opportunity for exercise again.

Knowing which joints are painful can target other therapies such as radiofrequency lesioning which are aimed at giving more prolonged relief should the standard injections give short lived help. It should be remembered that none of these techniques give a ‘cure’ as such as it is not possible to undo the ageing process.

They are aimed at making symptoms more tolerable whilst the patient gets on with life.

The third form of injection is aimed at looking for a pain source to direct surgical therapies. These are generally called discograms and consist of injections into a disc to determine if that disc is a source of pain. This is particularly used if there are many worn discs on an MRI scan and it is therefore impossible to tell which one is painful.

In summary, injections into and around the spine are a less invasive way of dealing with symptoms especially when used in conjunction with physical therapy.