Why a Spinal Cord Stimulator (SCS)?
Spinal cord stimulators may be used to treat or manage chronic pain disorders including:
-Back pain (especially back pain that continues even after surgery)
-Post-surgical pain
-Neuropathic pain
Spinal cord stimulation therapy works to try to mask pain signals before these reach the brain. A small implanted device (think pacemaker for the nervous system) delivers electrical pulses (controlled by the patient) within the spinal cord. It helps chronic pain patients better manage their ongoing pain and, ideally, reduce the use of opioid medications.
A spinal cord stimulator implant has become a reliable and efficient alternative for the management of unrelenting chronic pain. Pain that is unresponsive to other, more conservative therapies. The technology behind the stimulators has improved significantly in the past few years.
Current neuromodulation devices are both sophisticated, reliable and obtain significant positive results for various clinical situations of chronic pain -- failed back surgery syndrome, complex regional pain syndrome, even ischemic and coronary artery disease. Spinal cord stimulation is, and will continue to be, a valuable tool in the treatment of chronic and disabling pain.
Chronic pain is a leading cause for physical and emotional suffering, prescription pain med use, family and social disruptions, disability claims and missing work. As a pain specialist, finding solutions that are not medication-based is a priority. For me, neuromodulation with Spinal Cord Stimulation (SCS) is one of the more exciting developments in chronic pain management.
SCS has been in use for several decades in treating refractory neuropathic pain. Neuromodulation is based on the gate control theory of pain and is believed to decrease chronic pain signals by stimulating nerve fibers in the spinal cord.
First used in 1967 to treat cancer pain, since then pain stimulation has evolved. Now it is highly focused on the application of low-level electrical impulses which are delivered directly to the spinal cord.
The SCS is inserted in the epidural space to interfere with the direct transmission of pain signals traveling along the spinal cord to the brain. This is strategically positioned to replace unpleasant pain experiences with a background tingling sensation.
Recently, the outcomes of SCS have improved significantly. It is now a widely accepted form of therapy for chronic, previously unmanageable, neuropathic pain.
The hardware of the SCS consists of an electrode lead, a small extension cable, a pulse generator and a programming unit. The lead design varies in the number of electrodes from four to eight. Currently, there are two types of leads available: Percutaneous and Paddle. I work with percutaneous leads only.
The percutaneous electrode is inserted via Tuohy needles and is ideal for both the trial procedure and the permanent SCS implant. (The placement of a paddle lead requires open surgery — a laminotomy or partial laminectomy.) The implanted leads are then connected along tiny “extension cables” that lead to the pulse generator. The SCS system is then professionally programmed by adjusting the amplitude, pulse width and frequency.
There are two types of pulse generator systems currently available: a completely internal pulse generator (IPG) containing a battery, or an IPG that is supplied by external power source, through a radiofrequency antenna that is applied to the skin. Activation and programming of the IPG occurs through an external device. Patients can turn the stimulator on and off and they can control the stimulation amplitude and frequency as well as the width of the pulse generated.
As I already mentioned, SCS is particularly effective for relieving neuropathic pain. The most common pain of this type includes:
-failed back surgery syndrome (FBSS) with radicular pain
-complex regional pain syndrome (CRPS)
-peripheral neuropathy
-phantom limb pain
-angina
-ischemic (caused by low blood flow in or to a limb) limb pain
WHAT DOES THE PROCEDURE ENTAIL?
Currently, the protocols for SCS implantation stipulate a preliminary trial implant for positioning confirmation. During the trial implantation, the patient is asked to indicate the location of the vibration (paresthesia). It is important to confirm that this overlaps with the painful area in order to achieve the best effect.
During the trial period, which usually lasts 5 to 7 days, the amount of pain relief a patient experiences is monitored based on usual daily activities. The accepted benchmark for a successful trial is 50% or greater in the reduction of baseline pain. If benchmark relief is achieved, and the patient is satisfied with the results of the trial, steps for permanent implantation of an SCS system are started.
CAN THERE BE COMPLICATIONS?
As with any surgery, complications can occur. Those related to SCS have been reported to be at 30%. These complications include additional:
-revision needed
-hardware malfunction
-infection
-biological complications other than infection or local pain
-pain at the pulse generator site
-stimulator removal required due to lead migration, lead connection failure, and lead breakage.
In my experience, often in cases where there are complications, it is the need for a revision or a replacement that is necessary. Also, with the large number of SCS procedures I have done, most complications that have arisen are generally very minor.
In fact, the most common complication is related to hardware problems, including electrode migration or the need for reprogramming, with can be done with an office visit alone. Usually we will know if there is any issue within the first few days after the implant.
To prevent infection, precautionary measures such as a strict sterile technique, reduction in surgical time, and a perioperative antibiotic are implemented. Infection, in the very rare case one should occur, are managed with antibiotics and, in exceptional cases, the removal of the infection causing hardware.
Additionally, there is a low chance of an accidental puncture of the dura mater during the procedure. This can result in the leakage of cerebrospinal fluid (CSF) during the implantation of the SCS. There could be a temporary malfunction of the SCS as well as a possible post-dural puncture headache. Should this happen, I recommend a conservative initial treatment of rest and reprogramming several days post-op. However, in very extreme cases, an epidural blood patch could be required.
Finally, pain caused by the SCS stimulation sensation can necessitate either repositioning or removal of the electrode leads or the battery. Again, this occurs in very rare cases. SCS has been established as an effective treatment to provide long-term pain relief. With the reduction and/or elimination of the neuropathic pain, I see significant improvement in my patient’s quality of life, daily function and satisfactory non-medicated treatment of previously significant pain.
The key elements for the success of SCS are dependent on:
-Understanding how the SCS works.
-Finding a skilled and experienced doctor.
-Patient reaction to the procedure.
-Continued improvements to SCS products.