Spinal Cord Stimulator (SCS)
Overview
Spinal cord stimulation therapy is a method used to alleviate chronic pain by intercepting pain signals before they reach the brain. This treatment involves a small device, similar to a pacemaker, which delivers mild electrical pulses to the spinal cord. SCS can be a beneficial option for individuals experiencing chronic back, leg, or arm pain who have not found relief from other therapies. It aims to help patients manage their pain more effectively and reduce their reliance on opioid medications.
What is a Spinal Cord Stimulator?
A Spinal Cord Stimulator (SCS) device is surgically implanted under the skin, and it sends a gentle electric current to the spinal cord (see Fig. 1). Thin wires carry the current from a pulse generator to the nerve fibers in the spinal cord. When activated, the SCS stimulates the nerves in the area where pain is felt, leading to pain reduction. The electrical pulses modify and mask the pain signals from reaching the brain. Depending on the device, some SCS units use low-frequency currents that cause a mild tingling sensation called paresthesia. Others use high-frequency or burst pulses to mask pain without tingling. Most devices also offer a paresthesia-free setting.
It’s essential to understand that SCS does not eliminate the source of pain; instead, it changes the way the brain perceives it. As a result, the level of pain relief can vary for each individual. The target goal for SCS treatment is typically a 50 to 70% reduction in pain, although even a slight reduction can be significant, as it may enhance daily activities and reduce the need for pain medications. However, SCS does not improve muscle strength.
Not everyone will benefit from SCS. Some individuals may find the sensation unpleasant, and others may not experience relief throughout the entire pain area. To assess its efficacy, a trial stimulation is typically conducted, allowing patients to try SCS for a week. If it does not provide the desired results, the trial wires can be removed without causing harm to the spinal cord or nerves.
Components of SCS Device Systems
All SCS devices comprise three main parts:
- A pulse generator with a battery that generates the electrical pulses.
- A lead wire with multiple electrodes (8-32) that deliver electrical pulses to the spinal cord.
- A hand-held remote control for turning the device on/off and adjusting settings.
The type of SCS system may differ, with some being equipped with non-rechargeable batteries that require replacement every 2 to 5 years based on usage frequency. Rechargeable battery systems can last 8 to 10 years or longer, but regular daily charging is necessary.
The pulse generator in SCS devices offers programmable settings. Some units can sense changes in body position (e.g., sitting vs. lying down) and adjust the stimulation level accordingly. Other systems have independently programmable leads, providing coverage for multiple pain areas. Some units use sub-perception pulses with no tingling. The most suitable type of system will be determined by your doctor based on your needs.
Candidate Selection
To determine whether SCS is a suitable option, an evaluation of your physical condition, medication history, and pain duration will be conducted. A review of previous treatments and surgeries will be undertaken by a neurosurgeon, physiatrist, or pain specialist. Since chronic pain can have emotional effects, a psychologist may also assess your condition to optimize the chances of a successful outcome.
Typically, candidates for SCS have experienced chronic, debilitating pain for over three months in the lower back, leg (sciatica), or arm. Additionally, they may have undergone one or more spinal surgeries.
Spinal Cord Stimulator Trial
The trial phase is an essential step in determining if a patient is a suitable candidate for a spinal cord stimulator and if it provides adequate pain relief. During the trial, a temporary electrode array is placed near the spinal cord, typically through a needle or a small incision. The electrode leads are connected to an external generator, allowing the patient to control the electrical stimulation.
The trial usually lasts for a few days to a week, during which time the patient monitors their pain levels and evaluates the effectiveness of the spinal cord stimulation. This trial period provides valuable information about whether the spinal cord stimulator can sufficiently manage the patient’s pain and improve their quality of life.
Implantation of a Spinal Cord Stimulator
If the trial is successful and the patient experiences significant pain relief and functional improvement, the next step is the implantation of a permanent spinal cord stimulator system. This is typically performed as an outpatient procedure under local anesthesia.
The permanent spinal cord stimulator system consists of a small pulse generator, which is implanted under the skin in the lower back or abdomen, and the leads that deliver the electrical impulses to the targeted area of the spinal cord. The leads are carefully placed using fluoroscopic guidance to ensure accurate positioning and optimal pain relief.
Once the system is implanted, the patient receives instructions on how to use the stimulator and adjust the settings to achieve the desired pain relief. The patient can activate or modify the stimulation parameters using a handheld remote control.
Benefits and Considerations:
Spinal cord stimulation offers several benefits for patients with chronic pain. It can provide significant pain reduction, improve functional abilities, decrease reliance on pain medications, and enhance overall quality of life. However, it is important to note that not all patients will experience the same level of pain relief, and outcomes may vary.
As with any medical procedure, there are potential risks and considerations associated with spinal cord stimulator implantation. These include infection, device malfunction, lead migration, discomfort at the implantation site, and the need for future revisions or replacements. It is crucial for patients to have a thorough discussion with their healthcare provider to understand the potential risks and benefits specific to their situation.
Conclusion
Spinal cord stimulator trials and implantations are valuable tools in managing chronic pain that has not responded to other treatments. The trial phase helps determine the effectiveness of spinal cord stimulation in relieving pain, while the permanent implantation provides long-term pain management options. By working closely with healthcare professionals, patients can explore the potential benefits and considerations associated with spinal cord stimulation and make informed decisions to improve their quality of life.
SCS resources for patient guidance:
- Spinal Cord Stimulation Overview – Comprehensive information on SCS treatment.
- Animated SCS Video – Visual explanation of SCS.