A spinal cord stimulator (SCS) is a small, implanted medical device that manages chronic pain by delivering mild electrical impulses to the spinal cord. These impulses intercept pain signals before they reach the brain, replacing the sensation of pain with a milder feeling, or sometimes no feeling at all. Device longevity is a primary consideration for patients because the system relies on an internal power source that will eventually need replacement. The overall lifespan of the SCS system is almost entirely dependent on the battery, which is housed within the implanted pulse generator (IPG).
Device Technology and Expected Lifespan
The lifespan of an SCS is determined by its battery type, with two main technologies available: primary cell (non-rechargeable) and rechargeable systems. The leads, which are the thin wires placed near the spinal cord, are generally intended to remain in place permanently. Device longevity discussions focus on the IPG, which contains the power source and electronics.
Primary Cell Systems
Primary cell systems use a fixed battery designed to run until it is depleted, similar to a standard pacemaker battery. These non-rechargeable units typically have a fixed lifespan, with many older models lasting between two and five years before replacement is necessary. Recent advancements show median longevity reaching approximately 4.9 to 8.2 years in real-world studies, though this is highly dependent on how the device is programmed. This technology is often preferred by patients who wish to avoid the routine of external charging.
Rechargeable Systems
Rechargeable systems are engineered to last significantly longer because the internal battery can be replenished by an external charger worn over the device. This external charging process maintains the battery’s health, allowing the IPG to function for a longer period of time. Rechargeable systems are typically designed to last between seven and fifteen years before the IPG needs to be replaced. The median longevity for rechargeable IPGs has been reported to be around 7.2 to 9.0 years, offering a clear advantage in time between surgeries.
Factors That Impact Longevity
The projected lifespan of any spinal cord stimulator fluctuates significantly based on patient usage and programming settings. The rate at which the battery depletes is directly related to the energy demands placed on the implanted pulse generator. Higher voltage or amperage settings, used to achieve greater pain relief, require more power and shorten the battery life of both rechargeable and non-rechargeable systems.
Patients who rely on their device continuously throughout the day or use high-frequency stimulation programs deplete the battery faster. Different programming styles, such as high-frequency versus tonic stimulation, have distinct energy footprints that affect long-term power consumption. Manufacturers base longevity estimates on low-to-moderate settings, meaning the real-world lifespan is often shorter for patients with high daily usage.
For rechargeable units, the battery’s long-term health is tied to the patient’s adherence to the charging schedule. Failure to maintain a consistent routine affects the overall longevity and performance of the rechargeable battery. The implant location can also influence battery drainage, as sub-optimal placement may necessitate higher stimulation levels to manage pain effectively.
The Generator Replacement Process
When the implanted pulse generator nears the end of its life, the replacement process is typically scheduled proactively. The device is designed to communicate its battery status, often signaling its End of Life (EOL) through device warnings or physician monitoring during routine checkups. Replacing the generator before the battery fully dies ensures continuous pain therapy for the patient.
The surgery to replace the IPG, often referred to as a “battery swap,” is generally a minimally invasive, outpatient procedure. A small incision is made over the location of the existing device, which is usually in the lower back or abdomen. The surgeon carefully removes the old generator and connects the existing leads to the new device before closing the incision.
The existing leads are typically left in place near the spinal cord, avoiding the need for a full spinal procedure. This makes the replacement surgery far less complex than the original implantation. Recovery from the generator replacement is short, usually requiring a few weeks of restricted activity, and the patient will require new programming sessions to optimize the settings of the new device.