Rechargeable spinal cord stimulation (SCS) is considered a relatively safe and effective procedure for chronic pain, but it does not always work and there are some associated risks. Both rechargeable and non-rechargeable SCS devices have similar procedure-related risks.
SCS Procedure Risks
As with any invasive surgery, an SCS procedure has a small risk of allergic reaction and/or excessive blood loss. Other risks can include:
- Pain is not relieved. Even after a successful trial, many SCS patients do not experience the expected pain relief after the device is implanted. A review of the medical literature in 2014 found that about 40% of SCS patients may not achieve pain relief.1 Although, newer technologies are starting to show promise for better outcomes.2
- Infection. One study found that more than 4% of SCS patients develop an infection. For patients with diabetes, the infection rate went up to 9%.3
- Cerebrospinal fluid leak. Due to the close proximity of the spinal cord during the implantation of an SCS device, it is possible for the cord’s outer layer (dura mater) to become punctured and develop a cerebrospinal fluid (CSF) leak. A common symptom of CSF leak is a headache that gets worse with certain positions, such as leaning forward. A CSF leak typically goes away within a few days with rest and drinking plenty of water, but in some cases it requires surgery to treat.
- Paralysis. While rare, a more significant injury to the spinal cord can lead to paralysis of one or more limbs and/or the loss of a bodily function, such as bladder or bowel control.
Other risks are also possible. If a complication develops, such as an infection or pain, surgery may be needed to remove the SCS device.
Problems That Can Develop Later
A spinal cord stimulator is not permanently implanted unless a successful trial has been completed with a reported 50% or more improvement in pain relief. As such, most SCS devices that are permanently implanted provide a satisfactory level of pain relief either immediately or shortly after the procedure.
Even in cases where an SCS implant initially works as intended, problems can develop over time, such as:
- Electrode lead migration. If the leads start to move far enough away from where they were initially implanted, the device no longer can provide the same stimulation to the painful area. Lead migration is the most common complication after a successful SCS trial and permanent implant.
- Acquired tolerance. It is possible for an SCS implant to become less effective as the body becomes used to it. Sometimes an alteration to the device’s programming can alleviate this issue, but some people report that over time the device provides less pain relief. Modern SCS systems offer more variations in programming, which may prolong its effectiveness as the body’s response to the stimulation continues to change over time.
- Outside system interference. Theft-prevention sensors at stores may temporarily increase the stimulation of an SCS device. Some SCS devices may also experience damage or interference from other medical equipment, such as MRIs, pacemakers, defibrillators, or ultrasound.4
- Battery damage. Various problems can cause the rechargeable battery to become permanently damaged and work less efficiently, such as allowing the battery’s power to run down lower than the manufacturer’s recommendation.
Other complications and inconveniences are also possible. For example, while the stimulator is turned on, most patients are advised not to drive or perform other tasks that require precision coordination, such as lifting heavy objects or working atop a ladder. An unexpected increase in the device’s stimulation could cause a jolt and temporary loss of control.
Continuing Developments in SCS Systems
When rechargeable spinal cord stimulators first gained popularity more than a decade ago, they were advertised as pain relief lasting many years longer than a traditional SCS before needing a replacement surgery. However, the thinking today is not quite as simple. In recent years, the SCS market’s dynamics have been changing for two reasons:
- Traditional SCS systems are starting to last longer than in the past
- Technology is advancing quickly, which could cause some rechargeable SCS systems to seem obsolete years before they need to be surgically replaced
Some SCS systems that are on the market today have the ability to upgrade the software without needing to replace the hardware. Potential SCS candidates are advised to ask questions about whether or not future software upgrades could be beneficial to their health situation.