Spinal Cord Stimulators in the Treatment of Chronic Pain
Spinal Cord Stimulators in the Treatment of Chronic Pain
Spinal Cord Stimulators (SCS) have been in use to treat pain since 1967. They work by delivering mild electric stimulation to the nerves along the spinal column to modify nerve activity to minimise the sensation of pain reaching the brain. They can be extremely effective in alleviating chronic pain.
SCS do not only reduce abnormal pain signals reaching the brain but also restore the normal pain-inhibition pathways by stimulating the body’s natural chemical neurotransmitters that are used by the nervous system to communicate with each other.
SCS is used to largely treat neuropathic pain, which is pain caused by damage or disease affecting the somatosensory nervous system. It is most commonly used for neuropathic pain affecting the back and legs and typically used by approximately 25% of patients after back surgery. It can also be used effectively to treat complex regional pain syndrome (CRPS) in some patients. Success rates for SCS in the published literature range from 40-60%.
Who is a Suitable Candidate?
Not everyone is suitable for this procedure. Before patients undergo implantation they have to undertake a rigorous physical and psychological evaluation to make sure they are a suitable candidate. This is carried out by a multi-disciplinary team consisting of a pain specialist, a physiotherapist a psychologist as well as other clinicians depending on the patient’s condition and needs.
If this is successful the next step is a trial implantation. The SCS is inserted but not fully implanted for a period of between two to four weeks to allow full evaluation of the equipment.
At the end of the evaluation if it is felt by the patient and the team that the SCS has delivered beneficial results then they can proceed to a full implantation.
Timescales
It will likely take more than a year before the procedure is undertaken on the NHS. It is a comparatively expensive treatment and therefore may not always be available on the NHS. Funding aside, providing the candidate is suitable, implantation can be arranged within weeks on a private basis. However, the full and rigorous assessment process is required regardless of whether implantation is carried out privately or by the NHS.
Risks
As with any invasive procedure SCS implantation does carry some immediate risks including failure, local bleeding, bruising and infection, meningitis, epidural haematoma or abscess, dural puncture, post-dural puncture headache, neuropraxia (nerve damage) and post-procedural discomfort.
Longer term risks include dislodgement of electrodes, fracture of electrodes and battery or equipment failure.
Longevity
Batteries can only be replaced surgically. There are a wide variety of spinal cord stimulation devices on the market with different types and duration levels of battery packs. The volume of use by the client will have an influence on the life of the battery but, as a guide, batteries will need to be replaced approximately every 5 years.
New technology has developed spinal cord stimulators which use remote charging technology. This negates the need for surgical replacement by charging the SCS externally using a charging device over the implanted equipment. The new devices will become more widely available over time.
Lead fractures and failures and computer and software failures are other potential issues which may require surgical intervention. The software in the implanted device is updated annually by telemetry.
There is no definitive study or research demonstrating the efficacy of SCS which is why most studies report a 40-60% success rate at two years. This may largely be because the benefit of the treatment is individual to the patient. However, for patients with significant pain and disability where other treatments have failed to provide relief SCS may be a useful procedure to explore with their treating Consultant in Pain Medicine.