An epidural injection is a procedure used to alleviate pain arising from irritation to the spinal cord and nerve roots.
Brief Anatomy
The spinal column is made up of 24 moveable vertebrae. These vertebra consist of a large vertebral body at the front and a bony complex at the rear.
Sitting between the two in the middle is the spinal canal which runs the length of the spine and houses the spinal cord. The spinal cord is encased by the Dura which is a protective sheath filled with Cerebro Spinal Fluid. Located behind this is an area called the epidural space, however rather than being a space as the name suggests it is generally filled with fatty tissues and blood vessels.
Nerve roots branch away the cord within the Dura, travelling through the epidural space to supply the back and other areas of the body. The location of this supply depends on the which level the branches have orignated from with each spinal segment feeding a different area. (see ‘dermatome’ link for an animation of this). This is why the refered nerve pain that you feel can vary in location with injury or irritation to different parts of the spine. In the lumbar spine, the referral routes are to the legs and groin area as well as locally to the back itself.
The diagram below represents a side view of the spine and demonstrates how the nerve roots at most levels simply exit from the central cord either above or below the corresponging vertebra. contrary to popular belief, the spinal cord itself terminates at around the anatomical level of L1/2 and the nearer to this endpoint you get, the further the nerve roots have to travel to reach their exit point. Below this termination this distance is incresaed further and without the protective casing of the dura are more susceptibal to irritation from external anatomy or injury.
The Epidural
The sole purpose of the epidural injection is to deliver a direct dosage of anaesthetic/anti-inflammatory mix into the epidural space. Here, it is able to migrate around a small area and ’sooth’ the inflamed areas. With all the injection therapies (epidural, epidurogram, nerve root block, facet block) it is important to appreciate that in most cases it is not successful as a stand alone treatment. It should be considered to be an enabling intervention that allows you a window of opportunity in which to address the root causes. This may simply be altering your postures etc, or it may be working in tandem with professionals such as physiotherapists.
The old adage that a picture speaks a thousand words is very true especially with specialist interventions such as these. No matter how I explain it, viewing it is always much clearer so I strongly suggest you view the animation below. There are other external links available below which provide alternative descriptions and explanations which also helps with a broad understanding. Please be aware however that some of these are from American sources and although the gross procedure is the same, same of the finer techniques may differ slightly.
If you require information regarding the operative process undertaken by Nick and his team then please take a look at the downloadable ‘pdf’ booklet that has been designed for this purpose. It is located within the ‘pdf leaflets’ header from the drop down menu above.
