Crystal ball: post-surgical spinal pain


Dr Nigel Kellow, a spinal and interventional pain specialist at UME Group, predicts the evolution of treatments for post-surgical spinal pain and nerve injuries

State of play
It is increasingly common for people – particularly the elderly population – to undergo structural spinal surgery. After surgery, some patients find they have the same pain they had before the procedure, or that a new pain has appeared.

The most important thing for us at this point is imaging. After any spinal surgery, you typically need to combine MRI and CT scans to exclude any issues that require another surgical solution. If the problem appears to be tissue based, such as a swollen nerve, we can administer targeted injections of steroids. If nerves aren’t swollen but have been damaged, we would traditionally start with nerve pain drugs such as amitriptyline or gabapentin. If the symptoms don’t respond, we would move on to spinal cord stimulation. When a nerve has been damaged, abnormal signals can be sent from the spine up to the brain, causing pain. If we attach electrodes to that part of the spine, then stimulate those electrodes at a very high frequency, the current dampens down the abnormal signals to the point of almost blocking them, and the brain no longer registers those signals as pain.

On the horizon
When I started spinal cord stimulations, the intention was to give the patient a feeling of buzzing in the area where they felt the pain. We would steer the electrodes into a particular part of their spine and stimulate them at 50 Hertz. This worked well for a while, but the benefit wore off after a year or two. We found that higher frequency stimulation was much more effective, and effective for much longer periods. Now we use 10,000 Hertz.

For me, advances in spinal cord stimulation and other forms of neuromodulation remain the way forward for treating this kind of pain. While the technology does exist, it is still a niche treatment that is inaccessible to a large majority of people suffering such pain, which is unfortunate. The treatment is not as widely known as it should be, and the devices and implants are quite expensive. I’d like the technology to become cheaper and much more widely used. In the time I have been prescribing spinal cord stimulation there has been real progress in both the hardware used and the effectiveness of the treatment, and no doubt that will continue.

In the distance
As time goes by, I expect to see the devices we use evolve from the present rods with electrodes wrapped around them into more mesh-like structures. These would be put in place through a needle, then deployed sideways and lengthways inside the spinal canal. Such meshes would greatly increase the effectiveness of the interface between the electrode and the nerves while using less power, therefore needing much smaller, longer-lasting batteries.

I can also see the software improving to the point where it senses activity in the nerves and automatically delivers the appropriate level of current at a frequency calculated to negate those signals and stop the patient from feeling any pain at all. Done well, this could create a feedback loop without any intervention from a clinician, providing truly personalised pain relief at the moment it is most needed.

Finally, I’m hoping we will eventually see some kind of advance in the material science of the structural support hardware we use. At present, spinal surgery often involves titanium implants. This causes problems because the metal implants are completely rigid, while our bones are a little softer and want to flex a bit. New materials that provide the necessary support but offer more give than titanium would be hugely beneficial.

This article is from issue 9 of Prognosis. Read now.