Spinal Cord Stimulation (SCS)
What is Spinal Cord Stimulation?
Spinal cord stimulation (SCS) is an innovative and unique treatment option used to treat a variety pain conditions without the need for invasive surgery. While the concept of SCS has been around for over 40 years, the technology available to perform it has grown by leaps and bounds since that time.
Spinal Cord Stimulation is part of a larger field known as Neuromodulation – the concept that one neuron can be manipulated to regulate a larger and diverse population of other neurons.
SCS has been proven to reduce pain, improve activities of daily living, and even improve blood flow in patients suffering from any number of pain syndromes. This amazing technology has the ability to treat even the most stubborn pain syndromes and help patients eliminate the need for addictive pain medications.
The concept of SCS was born from a hypothesis by Melzack and Wall in 1965 called the “Gate Control Theory.” The basic essence of this theory is that the nervous system can process only so much input at any given time. Some input can take priority, or even overwhelm other input, thus preventing said input from making it through the spinal cord to the brain for acknowledgement. In other words, one sensation can commandeer the brain’s attention, leaving it unable to process other lesser sensations.
Pain, as it pertains to the Gate Control Theory, is processed and transmitted to the brain through Aδ and C fibers – small, fragile neuron filaments. Other non-painful sensations, like the ability to sense light touch and vibration, are transmitted on large, myelinated (the insulation tissue surrounding axons) Aβ. In the event both fibers are competing to transmit their signals through the spinal cord and into the brain at the same time, the nonpainful signals from the larger fibers will impede the painful signals from the smaller fibers – blocking the sensation of pain.
The most unique aspect of SCS is the ability to test it temporarily before implanting it permanently – this is called a spinal cord stimulator trial. The leads are inserted under the skin near the spinal cord for a few days and then removed with only a small Band-Aid to cover the site. This allows the patient to test and see if the procedure works before committing to the full version, the implant.
SCS goes by many names:
- Spinal Stimulator
This procedure is ideal for those who are hoping to avoid a painful and invasive spine surgery, as well as those who are not candidate for surgery due to risk or co-morbidities. The elegance of spinal cord stimulation is that one can “test drive” it first. Whether the trial is success or not, the patient will be no worse for wear. The same cannot be said for surgery where the consequences are irreversible and the success rate averages only 61%, with a strong likelihood the symptoms may worsen. A spinal cord stimulator trial is completely reversible and an ideal alternative to surgery.
Using technology very similar to a pacemaker for the heart, your doctor will place a small wire near the spinal cord. Just as a pacemaker sends signals to the heart to get it beating correctly, the SCS will send electrical signals to the spinal cord to make it communicate with the brain correctly.
The electrical signals sent by the SCS to the spinal cord are totally customized to each person’s pain. If your pain is more on the left, the signals are adjusted to the left. If your pain is more in the low back, your doctor will position the wires and the signal to account for the low back.
The length of a trial can vary from a few days to a few weeks depending on the physician and the part of the world in which the trial is being performed. Most physicians in the United States will conduct an SCS trial for 4-7 days. Our doctors at the Ainsworth Institute typically perform trials for 5-6 days. You will come in about 4 days after the trial so the doctor can monitor your progress and make some minor adjustments to the signals.
Is Spinal Cord Stimulation Right for Me?
If you suspect you may need surgery and want to do everything possible to avoid it, or you have already had surgery and still experience pain, SCS may be an option for you. The trial process is completely reversible and is done right in the office.
Contact the Ainsworth Institute to set up an initial evaluation to find out if you are a candidate for SCS.
The trial is a close approximation of what it would be like to have an implanted SCS, but without any of the surgical procedure involved in the implant. There is no cutting of any kind.
You will be given a remote about the size of a smartphone that will be externally attached to leads. This will allow you to play with the settings as much as you want and get an idea of what the real implant would be like. There will be an “on/off” switch and an “intensity” option with which you will be able to turn the stimulator as high or as low as you desire, like the volume on a remote. (Don’t worry, you cannot electrocute yourself. There is a governor that controls how high it can go!) There will also be a series of programs that will be post-operatively customized to different presets – think of these like the channel buttons on the television remote. One program may be for walking, while another may be for sleeping. These programs take into account that your pain will change throughout the day depending on what you are doing. This will allow us to fine tune the SCS to suit your specific needs.
The leads will be easily hidden under your clothing and the remote can fit in your pocket or purse so no one would be able to see them.
You will feel a pleasant tingling sensation or feeling of a light massage (aka paresthesias) overlying the area(s) of your pain. This will let you and your doctor know:
- If you are getting appropriate coverage from the device over the affected areas.
- If your pain is improved with the SCS.
- If the sensation from the SCS is acceptable.
You doctor may ask you to keep a “pain diary” to help keep track of the above numbered items to best assess if the SCS trial was successful.
Depending on your employment, most patients are able to function normally and go to work the next day. Consult your doctor if your job requires you to perform duties that would contradict the precautions listed above.
Most literature suggests a successful SCS trial is one where the patient describes at least 50% pain relief. A successful trial is also measured by a noticeable decrease in the consumption of pain medication or an increased in function and activities of daily living (ADL). Another important aspect of determining the level of success is if there was appropriate coverage over the painful areas. During the trial, if you things are not going well, contact the representative from device manufacturer as it may just need to be reprogrammed.
In some cases, it may not be readily apparent if the trial was a success; your doctor may elect to keep the lead(s) in for another week for more time to make an assessment. In other cases, a re-trial may be necessary.
Removing the leads could not be easier and will typically be performed in one of the exam rooms of your doctor’s office. Once the dressing is carefully lifted, the leads are gently tugged and slide right out. The removal is usually painless.
Regardless of whether or not the trial was successful, the leads are removed in the same fashion. All that will remain are two small dots on the skin.
In the event of a successful trial, your doctor will schedule you for a permanent spinal cord stimulator implant.
Procedure - Patient Details
The two greatest advantages of Spinal Cord Stimulation are:
- The ability to avoid surgery
- Test it out first
When considering SCS, your physician will first schedule you for a trial to see if neuromodulation is an effective strategy for treating your pain. A trial is typically performed in an outpatient setting, right in your doctor’s office. The technique is similar to that of an epidural injection. Light sedation is often provided for added comfort during the procedure, however local anesthetic is usually sufficient. Before the procedure, the medical staff will start an IV – this will allow your doctor to administer a small amount of antibiotic to reduce the risk of infection. You will then be asked to lay flat on your stomach with a small pillow under your abdomen.
Your skin will be cleaned with sterile soap to further minimize the risk of infection. Using a fluoroscopic C-arm (a real time X-ray device) your physician will be able to visualize the spine and the small spaces between the vertebrae where the leads will be inserted. Your doctor will thoroughly numb the skin and underlying tissue with local anesthetic for added comfort. At this point a small needle will be inserted in the same fashion as an epidural injection with the aid of fluoroscopy. Once the needle reaches the appropriate position, an SCS lead is threaded through and into the epidural space. The lead is slowly advanced to the correct level, all the while maintaining its position safely within the epidural space.
Once the tip of the lead reaches the predetermined area, the end outside the body will be connected to a controller and then activated. This is called the “testing phase.” Typically, the lead will have 4 to 8 contacts. Each contact can be remotely activated as either a cathode (positive) or anode (negative) – just like a magnet. The anode will send an electrical signal outward and the cathodes are used to steer the anode’s signal in a particular direction. These contacts can be set to any number of different combinations to create a truly customized signal specific to each person’s anatomy and pain complaints.
A representative from the manufacturer will perform the testing phase. He or she will begin to activate the contacts from the lead and try different combinations. All the while, you will be comfortably communicating and describing how you are sensing the tingling from the stimulator. Once the appropriate combination of contacts and signal intensity is found, you will begin to notice your pain fading. The needle will then be removed, leaving the lead in place under the skin. A dressing will be applied to secure the lead to the skin and the procedure is complete.
The SCS trial can be completed in as little as 45 minutes depending on the skill level of the physician.
Depending on your particular insurance company, you may be required to be “cleared” by a psychologist or psychiatrist to assess your level of understanding of the procedure.
Complications from SCS are considerably lower than that of traditional surgery. They range from simple problems like a lack of appropriate coverage of paresthesias over the area of pain, to the movement of the lead away from the “sweet spot” in the cord. These are easily remedied by having the system reprogrammed. During the trial phase, complications tend to be less as the system is in for only a few days. Another possible complication is infection. As the lead is not completely under the skin (like an IV line in the hand), there is the chance bacteria from can find its way inside the body. The longer the trial, the larger the likelihood of an infection occuring. This risk is mitigated with the use of intra-trial antibiotics. If you experience a fever during the trial, call your doctor immediately as the lead will need to be removed as soon as possible. The overall chance of infection is as low as 2.5%.
Are there any precautions during the trial?
- No showers or baths during the trial and for 24 hours after the leads are removed
- You may be asked to take antibiotics during the trial to help reduce the risk of infection
- Do not change the dressing or remove it – leave that to the doctor
- No bending, twisting or lifting heavy objects as this may cause the lead(s) to move
- No flying
- Avoid driving or sitting for extended periods of time
- Continue taking ALL medications as you were prior to the trial – you may notice that you need less pain medication during a successful SCS trial as the pain signals begin to be blocked
Evidence of Performance
The evidence in support of neuromodulation with SCS is overwhelming. The literature has firmly established that SCS is effective in treating an impressively large array of different pain types. The idea of using electricity to control pain dates to back B.C. where ancient Greek practitioners used the electrical impulses emitted from electric eels in clinical foot baths to relieve pain and improve blood circulation. The eels were capable of producing up to 600 volts in a single discharge and were popular in treating arthritis. Famously, the torpedo fish was by Scribonus Largus, a physician of the Roman Emperor Claudius, to treat a variety of ailments, including pain.
While we still do not completely understand why or how neurostimulation works, there are several things we do know about it. SCS has been shown to increase gamma-Aminobutyric acid (GABA) in the dorsal horn of rats as seen in laboratory research. GABA is a neurotransmitter that has been widely studied in the transmission of pain. We also know the pain relieving effects of SCS are not reversed by the administration of Naloxone – the reversing agent of morphine and other opiates., The body releases its own (endogenous) opioids to control pain internally to a certain extent; these are called endorphins. This suggests SCS has no effect on these endorphins and the other endogenous pain-relieving mechanisms of the body.
Another interesting fact regarding SCS is its ability to decrease the activity of wide-dynamic range neurons., Wide-dynamic range neurons (WDRN) are particularly important in the transmission of pain. These neurons will fire at an increasing rate when exposed to pain or other noxious signals. Even more important is that these neurons are implicated in sustaining pain in states such as Complex Regional Pain Syndrome (CRPS) or Reflex Sympathetic Dystrophy (RSD). WDRN have been implicated in the wind-up phenomenon (concept that there is a perceived increase in pain intensity over time when a given painful stimulus is delivered repeatedly) and in allodynia (pain is triggered by seemingly painless stimulus, i.e. light touch). By decreasing the firing rate of WDRN, SCS can potentially stop and even reverse pain caused and perpetuated in certain pain-states.
The effects of SCS extend beyond that of just the nervous system. Neurostimulation has been shown to alter the tone of the sympathetic nervous system and improve blood flow. SCS has been shown to cause blood vessels to dilate thus increasing flow rates in the extremities; this is particularly important in those with diabetes and peripheral vascular disease. This aspect of SCS has been used in Europe to treat chronic chest pain and angina.
According to a study by Kumar et al in 1991, the five most common pathologies treated by SCS are:
- Peripheral neuropathy
- Failed back surgery syndrome (FBSS)
- Multiple Vascular Disease
- Multiple Sclerosis
Success rates with SCS are well documented. Henderson et al published a study in 2006 reporting 70% reduction in pain with SCS. In a study by North and Wetzel in 2002, patients reported on average 88% pain relief with SCS. Perhaps the most influential publication to date on the efficacy of SCS is a 15-year study by Kumar. Dr. Kumar followed patients implanted with a spinal cord stimulator for 15-years and reported an average of approximately 60% pain relief across all patients, with 43% reporting excellent pain relief.2 The authors went on to report an average success rate of 54% across 16 reported studies as found on a literature search of all published reports on SCS at the time.
Kumar’s publication was truly groundbreaking as the authors went on to delineate not only the actual success rates of SCS, but what pain states seem to response the best. The largest percentage of successful response to SCS was noted in peripheral neuropathy (73% – 14/19 patients) and Reflex Sympathetic Dystrophy (100% – 13/13 patients). FBSS had a success rate of 52%, and a similar literature search, it was found to be successful in 53% of patients across 10 studies. Kumar went on to describe that patients without surgical procedures prior to implant respond better, and if surgery was present in the history, having a shorter transition time to implant improved the outcome.
The findings that neuroaugmentation has preferential success for some pain types (neuropathic) and likely failure in others (nocioceptive) has been seen in several studies. It has been proposed that SCS is most lucrative in neuropathic or sympathetically-driven pain states – with success rates approaching 70%, likely due in no small part to its ability to directly affect the sympathetic nervous system. North et al reported that SCS was successful in producing pain relief that exceeded 50% for patients in follow-up as long as 20 years and accomplishing 60% relief in arachnoiditis., Meglio et al reported in 1989 that SCS was most effective in vasculopathic pain, low-back pain and neuropathic pain (post-herpetic neuralgia) and was the least effective in cancer pain and de-afferentation models.
With the failure rates of spinal surgery hovering around 40%, re-operation after a failure is an even riskier proposition. According to a study conducted by North et al. in 2005, 47% of patients with FBSS who received SCS found that it relieved their pain by 50 percent or more; this is significantly more than the mere 12% who reported pain relief after a second operation. Timing with SCS in FBSS is also extremely important. The sooner an SCS system is implanted for the treatment of FBSS after the date of their previous failed surgery, the higher the likelihood of success., North proposed that SCS had success rates reported as high as 88% in FBSS suggesting it may even be superior to re-operation.
SCS has also been shown to decrease the amount of medication need to treat pain. Studies have shown patient have been able to decrease their medication usage 45-50% on average,, while one study showed 68% of patients were able to eliminate the need for medications completely. Patients treated with SCS show significant improvement in their daily activities, and a higher rate of returning to work.
The Ainsworth Institute is Here to Help
If you are suffering from chronic pain and would like to see if you may be a candidate for this revolutionary treatment, contact the Ainsworth Institute of Pain Management today. Our doctors are experts in the use of Spinal Cord Stimulation…not just in New York, but across the country. Schedule an appointment today with one of our Board Certified Physicians to learn more about SCS.
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