I will try to give a basic outline, without being too medical!  There are some links from Guy’s and St Thomas’ hospitals pain management and NICE at the end of the page for anyone wishing to read at greater length.

Spinal cord stimulation is a treatment that can be used in conjunction with other therapies to help in the management of chronic pain.  It is important to remember that there is no definitive cure for chronic pain, and that the majority of those living with this pain will have found other treatments ineffective.  These might include surgery, medication, physiotherapy and other complementary therapies such as acupuncture.

I have described the spinal cord stimulator as an internal TENS machine in the past – that is an implantable device that consists of a battery pack and leads carrying electrodes. The leads are implanted into the epidural space – the area between the spinal cord and the internal surface of the back bone. Here the electrodes deliver an electrical charge to areas of the spinal cord which have been identified as the regions producing the pain messages delivered to the brain.  These charges interfere with the feelings of pain and thus alter/mask the sensation that finally is interpreted by the brain.  The internal battery/neurostimulator is programmed according to the individual’s needs, and this can be altered in frequency and intensity by a hand held patient programmer.

In the UK NICE guidelines recommend that people with the following diagnoses may be considered for spinal cord stimulation:

• failed back surgery syndrome
• complex regional pain syndrome
• neuropathic pain
• have moderate to severe chronic pain measuring greater than five out of ten on a pain rating scale, if they are 18 years +, have tried other treatments without success, are willing to reduce medications and have the capacity to care for the equipment.

The medical professionals will stress that this treatment does not help everyone and that in order for it to be considered worthwhile to perform the procedure, the relief needs to be pain reduction of 70%+.  This is why a trial is conducted initially to assess just how the individual responds to the electrical impulses – for some people the feeling generated is worse than their pain, or may increase the pain.

There are 2 methods for for implanting the trial leads – “percutaneous” and “tunnelled”.  The first is a quicker, less invasive procedure where the lead is thread through a large needle and pushed under the skin into the epidural space.  Whilst quicker to perform, if the trial becomes a full implant these leads must be removed and new tunnelled leads inserted – there is no guarantee that the electrodes will be in exactly the same position again.  But if the trial is unsuccessful, the leads can be removed in clinic.  The “tunnelled” trial, as suggested by the name, involves the leads being physically tunnelled into the epidural space and, if the trial is successful, these leads remain in place.  However if unsuccessful, the patient must have them removed surgically as it was a greater procedure initially.  There are risks attached to both methods.

I hope that this is helpful and that the following links fill in any gaps!

http://www.guysandstthomas.nhs.uk/resources/patient-information/perioperative/pain/spinal-cord-stimulation.pdf

https://www.nice.org.uk/guidance/TA159/chapter/1-Guidance