By: 7 August 2015
Acting on impulse – spinal cord stimulation

Acting on impulse

SSN talks to neurosurgeon Stana Bojanic about how spinal cord stimulation can be used to treat chronic neuropathic pain

Interview by Ann Blythman

Spinal Surgery News caught up with Stana Bojanic to discuss her spinal cord stimulation service (SCS) which is one of the largest services in the country treating patients with chronic neuropathic pain syndromes. We were keen to understand from her experience which type of patients can benefit from the therapy and at what point in a patient’s treatment pathway they should be considered for referral.

How long you have been involved in SCS as a therapy and how did you set up your service at the John Radcliffe?
I have been a consultant neurosurgeon since November 2004 and have been involved in SCS since then. Initially, we had difficulty obtaining funding for these implants but since NICE approval, funding has been granted for patients with neuropathic pain following spinal surgery and for chronic regional pain syndrome, and our service has grown hugely. We get referrals from our region (approximate population 2.5 million), which stretches from Kettering to Swindon to Wexham Park and the areas in between. We also, until recently, covered the Southampton area and we have provided a surgical implant service for some of the East of England. I am pleased to report that these areas now have local services.

How would you describe SCS as a therapy?
SCS directs electric impulses to the back of the spinal cord. There are many explanations for how it works but, broadly speaking, these signals seem to stimulate part of the pain pathway that inhibits pain. Mechanisms are complex as there is also evidence that SCS can increase some of the neurotransmitters that inhibit pain (gamma-aminobutyric acid, for example) and reduce some of those neurotransmitters that drive or excite pain, such as glutamate and aspartate. This results in paraesthesia being experienced in the area of pain.

In your experience, what does an ideal back/leg pain patient look like?
There is Level-1 evidence that SCS should be considered in patients who have had a spinal decompression or spinal fusion and still have pain [1]. All patients should have failed conventional medical management and attended a pain management programme. Assessment of suitability for this implant is undertaken by a multi-disciplinary team that may include a pain specialist, specialist nurse, neurosurgeon and psychologist. General medical conditions should also be considered – so patients with a bleeding disorder, sepsis or active psychiatric history – should not undergo implantation. Relative contraindications include immunosuppression, presence of a demand pacemaker or implanted defibrillator and spinal stenosis at the level of implantation. Patients should have a general level of fitness to undergo the procedure.

How has SCS evolved as legitimate treatment over the last 10–20 years?
We have routinely treated patients with neuropathic pain following spinal surgery and patients with chronic regional pain syndrome. In this group, new electrodes and different methods of stimulation have led to greater success with treatment of lower back pain over recent times. We have also been able to treat patients with neuropathic abdominal and pelvic pain with newer electrodes that allow greater programming choice. Post-amputation pain can also respond to spinal cord stimulation, as well as brachial plexopathy.

SCS can be implanted using either a percutaneous or a surgical approach. Are there different situations where one approach would be considered more beneficial over the other?
Both procedures can be considered for spinal cord stimulation. A surgical approach can be more beneficial if there has been extensive spinal surgery and implantation of percutaneous wires would be difficult. There is a lower migration rate with surgical electrodes but the procedure does involve undertaking a laminotomy to insert the electrode.
A percutaneous approach is undertaken via needle insertion so is less invasive and can be done as a day-case procedure. There are now percutaneous MRI-compatible wires available, which improves choice in patients who may require serial MRI investigations.

The uptake of SCS in the UK is incredibly low despite having a NICE technology appraisal. Why do you think this might be? And what do you consider to be the biggest barriers to referral for the therapy?
I think one of the main reasons is reduced awareness that this therapy is available and is a possibility in patients with neuropathic pain. There are then several limiting factors along the pathway and these are all, unfortunately, resource driven. Only a small number of pain anaesthetists and neurosurgeons provide this service compared with the population numbers that could benefit. This puts pressure on those centres providing SCS and waiting times can be long. Investment should be made in pain services so that patients coming through the system are identified and referred earlier on.

In your opinion does the delay in referral for SCS impact on the outcome or decision to treat?
Yes. There is increasing evidence to suggest that treating/reducing pain earlier on reduces the ‘up regulation’ of the pain pathways and leads to a better response to treatment.

Many patients want to find a way to avoid or reduce the side-effects of strong medication. Have you experience of patients reducing their medication once they have received SCS therapy?
Part of SCS therapy is to improve pain control, reduce medication and improve quality of life. Long-term opioid medication causes many side-effects. These are often not all recognised, and include weight gain, lethargy, loss of libido, poor sleeping patterns, constipation and nausea. Opioids affect the immune system and the ability to fight infection and in some cases long-term use can cause increased sensitivity to pain.

What other significant quality of life improvements have you experienced with your patients implanted with SCS?
We have seen patients increase their activity once their pain is better controlled. Reduction of medication has been a big factor and we do have patients return to work.

Some people consider SCS to be too expensive, what would your response be?
There have been several papers published showing that SCS is cost-effective when compared with conventional medical management. I think the concern is the initial implant cost but studies by Taylor et al. [2] and Kumar et al. [3] demonstrate a clear cost saving over time.

What significant thing have you learnt about SCS as a therapy over the years?
As with any procedure, patient selection is key, together with a good multi-disciplinary team.
Do you think that awareness of SCS as a therapy is too low among spine surgeons? If so, what can be done to change this?
Yes I do. Hopefully articles like this will help but we as a group should be active in approaching societies such as the British Association of Spinal Surgeons to present at their meetings. I think we are good at networking within our groups – such as the British Pain Society and Neuromodulation Society of UK and Ireland – but I think we need to expand our target audience.

If a surgeon has a patient that suffers from intractable chronic neuropathic pain despite corrective spine surgery, what would you consider the next step should be?
If they have been to their local pain clinic/pain management programme and they are not improving, then referral for SCS might be appropriate.

What do you believe is the future of SCS therapy?
We live in very exciting times at the moment with huge development in the technology available. This provides more choice and flexibility, with therapy options for clinicians and patients alike. Research is being undertaken into the management of lower back pain and I think this is a real possibility with difference types of stimulation. National data collection is very important and this is in progress. SCS for other conditions, such as angina and diabetic neuropathy, is in use and being researched. Occipital nerve stimulation for cluster headache and migraine has had good results.

Kumar, K., Taylor, R.S., Jacques, L., et al. (2007) Spinal cord stimulation versus conventional medical management in patients with failed back surgery syndrome. Pain 132(1-2), 179–188
Taylor, R., Van Buyten, J.P. & Buchser, E. (2005)Spinal cord stimulation for chronic back and leg pain and failed back surgery syndrome: a systematic review. Spine 30, 152–160
Kumar, K., Malik, S. & Demeria, D. (2002) Treatment of chronic pain with spinal cord stimulation versus alternative therapies: cost-effectiveness analysis. Neurosurgery 51(1), 106–116

Stana Bojanic is a consultant neurosurgeon at the Oxford University Hospitals NHS Trust. Ann Blythman is market development manager at Medtronic Inc.

The Oxford University Hospitals NHS Trust neurological surgery team has an international reputation for the treatment of children, movement disorders, brain tumours and vascular disorders. The neurosurgical department encompasses Oxford Functional Neurosurgery, dedicated to the surgical alleviation of movement disorders and neuropathic pain syndromes.