Spinal Cord Stimulation – Indications, Contraindications

Spinal cord stimulation uses pulsed electrical energy near the spinal cord to manage pain. Initially, this technique applied pulsed energy in the intrathecal space.[rx] Presently, neuromodulation involves the implantation of leads in the epidural space. A similar principle utilizes the central nervous system and the peripheral nervous system stimulation in deep/cortical brain stimulation and peripheral nerve stimulation, respectively. Neurostimulation modalities arose as a response to treating the gate control theory of pain by Melzack and Wall. In summary, they posed that pain impulses provoked in the periphery, which are carried by C fibers and A-delta fibers, could be interrupted by stimulating larger A-beta fibers. This interruption is facilitated by the common nerve synapse location in the substantia gelatinosa of the dorsal horn. In other words, stimulation of the touch and vibration nerves “closes the gate” on ascending pain impulses that carry noxious pain stimuli cephalad.[rx] Multiple pain systems are responsible for the sensation of pain; these systems are composed of integrative neuronal sets (conduct excitatory or inhibitory signals on the nociceptors).[rx] The interrelation that exists among these three systems at all times is responsible for the perceived sensation of pain and the responses associated with it. First, nociceptors receive signals of noxious temperature, chemical, or mechanical stimuli (peripheral neurons). They send this information to second-order neurons located in the spinal cord, mainly in the dorsal horn (central pathways), which are then transmitted via projection neurons to the brainstem (integrative neurons).

Nociceptive fibers (peripheral pain receptors)

•  Unmyelinated C fibers and lightly myelinated A-beta fibers (small nociceptive fibers, which conduct pain)
•  Myelinated A-beta fibers (large non-nociceptive fibers, which conduct touch, pressure, and vibration)
• Central pathways (relay neuronal signals to higher brain structures)
• The primary integrative site in the brain is the thalamus, but other structures also participate in response to pain. Once the brain receives the pain signals, several reactions are generated almost immediately to modify and respond to these signals. These reactions include, but are not limited to, somatic and autonomic reflexes, negative or positive feedback to increase or reduce the pain, endocrine and emotional responses, cortical awareness, or the pain, as well as the memory of the event.
• The gate control theory of pain, mentioned above, is directly associated with these pain systems. It establishes that C fibers, A-delta fibers (nociceptive), and A-beta fibers (non-nociceptive) can all carry information from the injury site to two different cell types in the dorsal horn of the spinal cord, transmission cells, and inhibitory neurons. Both the nociceptive and non-nociceptive fibers can activate the transmission cells, opening the gate of signals sent to the brain. However, only the non-nociceptive fibers can activate the inhibitory cells, therefore closing the gate.[rx]
• Even though the gate control theory was the initial guiding mechanism of action, modern research has demonstrated that the underlying mechanisms are not clearly understood. There is evidence to suggest that dorsal column stimulation applies a different mechanism of analgesia when utilized for neuropathic pain versus ischemic pain.[rx] In neuropathic pain, evidence suggests that by altering local neurochemistry, stimulation suppresses hyperexcitability of the wide dynamic range neurons by increasing GABA and serotonin release, which suppresses levels of the excitatory cytokines glutamate and aspartate.  On the other hand, the current belief is that ischemic pain alleviation occurs by alteration of sympathetic tone, achieved by restoring a favorable oxygen supply and demand balance.

Anatomy and Physiology

For the spinal cord, a stimulator leads to be introduced into the spinal cord, the epidural space needs to be accessed using an epidural needle. Therefore, there is relevant anatomy that merits consideration during this procedure.

• Vertebrae: Each vertebra is composed of a vertebral body (anterior) and a vertebral arch (posterior). The arch further divides into two lateral pedicles connected to two posterior laminae, a single spinous process, and two transverse spinous processes that extend laterally at the point where the pedicles connected to the laminae. The connection between two adjacent vertebrae at the level of the pedicles forms the foramina. There are 7 cervical, 12 thoracics, and 5 lumbar vertebrae, followed by 5 false or fixed vertebrae forming the bony sacrum and coccyx.[rx]
• Ligaments: After going through the skin and subcutaneous tissue, the first ligament encountered by the epidural needle is the supraspinous ligament, which connects one spinous process to another in adjacent vertebrae. The interspinous ligament then follows. The ligament flavum is much thicker and connects the lamina of adjacent vertebrae. Two other ligaments found on the anterior aspect of the spinal cord, are the anterior and posterior spinal ligaments, which connect adjacent vertebral bodies.[rx]
• Spinal cord: The spinal cord is surrounded by the dura mater (outermost layer), arachnoid mater, and pia mater (innermost layer, directly overlying the spinal cord). It extends from the medulla to the level of L1 in adults. At this level, one finds the conus medullaris. Below the CONUS, the spinal nerve roots become elongated and parallel, forming the cauda equina, which allows nerves to move freely within the CSF and makes this location preferable for the insertion of an epidural needle.[rx]
• Arterial supply: The arteries supplying the spinal cord derived from the vertebral arteries in the cervical spine, as well as the intercostal and lumbar arteries in the thoracic and lumbar spine. These arteries anastomose with other spinal cord vessels, forming the pial plexus. There are anterior and posterior branches, which supply the ventral and dorsal roots of the spinal cord. In the dorsal (sensory spinal cord), the posterior spinal arteries anastomose, protecting this area of the spinal cord from ischemia. On the other hand, there is a single anterior spinal artery that supplies the ventral (motor) spinal cord. One of the largest arteries supplying the anterior spinal cord is known as the artery of Adamkiewicz, which most commonly enters the vertebral canal through the L1 foramen. It supplies the lower two-thirds of the spinal cord. Damage to this artery from an improperly done epidural may lead to bilateral lower extremity paralysis.[rx]
• Venous supply: There is a vertebral venous plexus that drains into the vertebral canal. These veins empty into the azygos vein that ultimately empties into the superior vena cava (SVC). This plexus is of particular importance in patients with masses or increased intraabdominal pressure compressing the SVC. When this occurs, there is a backup of blood into the epidural space, which increased the risk of cannulating the veins with the epidural needle.[rx]

Spinal Cord Stimulator Types

Spinal cord stimulators come in three main types:

• A conventional implantable pulse generator (IPG) is a battery-operated spinal code stimulator. A battery is placed in the spine during an operation. When it runs out, the battery must be replaced with another surgery. This device can be a good choice for people with pain in just one body part because it has a lower electrical output.
• Rechargeable IPG works similarly to the conventional device, with the difference that the battery can be recharged without another surgery. Because the energy source is rechargeable, these stimulators can put out more electricity. This may be a better choice for people with pain in the lower back or in one or both legs, as the electrical signal can reach further.
• A Radiofrequency stimulator uses a battery that’s outside the body. This stimulator is rarely used today because of newer designs and better technology. It has rechargeable batteries, and like the rechargeable IPGs, it may be better for people with pain in the lower back and legs because of the device’s power.

Your surgeon will explain how to operate the device and adjust the intensity of the electrical signal, which all three types of stimulators support. Different body positions may require different stimulator settings, such as one setting that works better for sitting and another for walking). To help you easily access the most used settings, most devices allow doctors to save two or three preset programs. Some newer devices feature several waveforms for electricity delivery, including high frequency, burst and high-density stimulation.

Indications of Spinal cord stimulation

• Often, patient selection is the most challenging aspect of the decision to offer neurostimulation. Numerous patient factors are, at first, seemingly unrelated to patient response to treatment, but play a significant role in the likelihood of a positive response to therapy. Many of these are social factors. Any implantable device will require adequate follow-up, re-programming, wound management, and sometimes wireless recharging of the device. Ultimately, SCS requires the active participation of the patient in their care and ownership of the responsibilities involved in the continuous management of their pain syndrome.
• Apart from social factors, one of the strongest correlations to success is complex regional pain syndrome (CRPS). Additionally, a response to sympathetic nerve block may correlate positively with stimulation therapy.[rx] Level A evidence exists for failed back surgery syndrome (post-laminectomy syndrome), peripheral ischemia, peripheral neuropathy, and angina pectoris.[rx] However, dorsal column stimulation has shown success for many types of neuropathic and radicular pain syndromes. This modality is particularly useful in patients with pain refractory to medications, physical therapy, psychotherapy, chiropractic therapy, and other procedural interventions.
• Factors that do not seem to have a positive or negative correlation with SCS therapy include patient age, duration, intensity, and laterality of pain.[rx]
• Back pain, especially back pain that continues even after surgery (failed back surgery syndrome)
• Post-surgical pain
• Arachnoiditis (painful inflammation of the arachnoid, a thin membrane that covers the brain and spinal cord)
• Heart pain (angina) untreatable by other means
• Injuries to the spinal cord
• Nerve-related pain (such as severe diabetic neuropathy and cancer-related neuropathy from radiation, surgery or chemotherapy)
• Peripheral vascular disease
• Complex regional pain syndrome
• Pain after an amputation
• Visceral abdominal pain and perineal pain

Contraindications of Spinal cord stimulation

SCS may be contraindicated in people who have coagulation-related disorders or are on anticoagulant therapy.^[rx] Other contraindications include local and systemic infection, pacemakers, or those people for whom pre-surgical imaging studies show have anatomy that makes placement difficult, or if concerns arise during psychological evaluation.^[rx][rx][rx]

• Most of the studies that currently exist regarding SCS therapy are either small prospective studies or retrospective studies. For this reason, there are relatively few guidelines regarding contraindications for this procedure.
• As with other elective procedures, the standard contraindications apply. These include:

  • Infection at the surgical sites
  • Aberrant anatomy at the surgical sites that would preclude safe placement
  • Uncontrolled systemic illness
  • Uncontrolled bleeding diathesis
• Anticoagulation is typically held per ASRA guidelines. The inability to hold anticoagulation due to life-threatening clotting disease or proximity to cardiac surgery would be a contraindication as well.
• A study by Eijs et al., which looked at 36 patients with CRPS, found that one of the relative contraindications for SCS therapy is mechanical allodynia (painful sensation experienced by light touch). The authors found that patients experiencing mechanical allodynia, which was brush-evoked in this study, had a 31% pain reduction compared to 81% pain reduction in patients with CRPS without allodynia.[rx]
• Other indicators of poor SCS outcomes include symptoms of active depression, anxiety, somatization, and poor coping skills.[rx] Therefore, a psychological evaluation is necessary before considering a patient for an SCS device. Of note, the psychological process of catastrophizing (believing that something is worse than it actually is) does not interfere negatively with SCS therapy.[rx]
• Patients with the stump, phantom limb, or paraplegic pain do not seem to benefit from SCS therapy.[rx]

Equipment

• Spinal cord stimulators are composed of three main parts: the electrodes or leads, which can be cylindrical or paddle, the implantable pulse generator (IPG) or batteries, and the charging and reprogramming equipment, which includes a remote control.
• Many different companies currently make these devices. However, the bulk of the neuromodulation market is primarily three companies.[rx]
• All these companies offer the option of rechargeable IPG devices that last for up to 10 years years. This setup allows patients to use higher voltages without depleting the battery, increases the reprogramming options, and requiring less frequent replacement.
• Additionally, each IPG has a different level of MRI conditionality. If MRI imaging is pertinent in the healthcare management of the patient in the future, a review of the conditionalities of each IPG should take place before making a selection.

Personnel

Preparation

• Pain physician visit – evaluation/patient selection process to determine if the patient’s pain syndrome would benefit from neuromodulation and if they have exhausted conservative therapy
• Psychological evaluation – active or untreated psychological disorders can lead to poor outcomes, and a licensed psychiatric professional can help determine if a patient would be an ideal candidate for a spinal cord stimulator
• Diagnostic imaging – Ideally MRI imaging of the epidural space and anatomy of the lead’s final location is helpful in planning approach and provides diagnostic value to a patient’s pain distribution
• Trial stimulation – a trial with one or more implanted leads connected to an external IPG, allows the patient to determine if all pain areas are covered, and if he or she has at least 50% decreased pain and or 50% increased functionality
• Permanent implantation – reimplantation of one or more leads and IPG.

Technique

• The technique associated with SCS is considered one of the most challenging procedures in interventional pain management. The implantation of the SCS device divides into two steps, the trial, and the permanent SCS implantation. Even though the same or similar equipment is used for these procedures, the technique utilized for each step changes significantly. The trial allows the patient to evaluate the effect of the SCS device on their particular pain pattern. Typically, patients return to the clinic within ten days after the trial procedure. If they have over 50% pain relief, increased activity level, and/or decreased medication use during this time, the trial is considered successful, and they can be scheduled for a permanent SCS procedure.[rx][rx]
• Both the trial and the permanent SCS placement are sterile procedures performed in the operating room under sedation. Patients should receive instructions to shower with chlorhexidine before these procedures. Preoperative cefazolin or clindamycin are prescribed before the permanent SCS placement for coverage of skin flora. On the day of the procedure, the patient is placed prone on the operating table. Skin prep is with alcohol-based chlorhexidine scrub and then covered with towels and a full surgical drape. An epidural needle is placed on the skin. A lead is inserted into the epidural space via the epidural needle under fluoroscopic guidance. Epidural needle placement is at an angle of fewer than 45 degrees to facilitate threading of the lead. A perpendicular angle needs to be avoided at all times since this would require bending the lead as it is introduced into the epidural space. The lead is advanced through the posterior paramedian epidural space until the appropriate location providing coverage of the patient’s pain region, which may require one or more leads. Most commonly, this location ranges between T8 and T10.

There are two types of SCS trial, percutaneous lead trial (most common) and permanent lead trial

• SCS percutaneous trial
  • In this approach, after placement of the lead or leads in the appropriate location on the spine, the epidural needle is removed. The lead is then adhered to the skin using a suture, surgical adhesive, or skin glue. The remaining portion of the lead connects to an external pulse generator, which is also secured to the skin using a suture or skin glue, a chlorhexidine patch, and a sterile dressing. The device is programmed perioperatively and once again in the recovery room before discharging the patient home.
  • Even though this procedure requires the patient to return to the OR for a permanent lead placement if the trial is successful, it is the preferred method by most providers. It avoids a second incision and postoperative pain during the trial. It also decreases the risk of infection when compared to the permanent trial.[rx]
• Permanent SCS trial
  • In the permanent trial method, once the leads are in the appropriate location, a local anesthetic is injected around the epidural needle. A midline incision is made through the skin down to the supraspinous fascia. The leads are anchored in this space using a nonabsorbable suture and an anchoring device. This device is placed as close as possible to the fascia with the tip protruding into the fascia, which minimizes bending the leads. The anchoring device is secured using a nonabsorbable suture. Two approaches are possible to tunnel the leads and secure the IPG. In the first approach, the midline incision is made larger. An extension wire is connected temporarily to the permanent lead, and it helps to tunnel the lead from the incision to the overlying skin. In the second approach, there is a lateral skin pocket made in the flank, where the IPG is placed. Less commonly, this pocket can be in the posterior superior gluteal area, the lower abdomen, or the pectoral areas. The permanent lead is tunneled from the midline incision into the lateral pocket. At this point, an extension wire is connected to the permanent wire to tunnel the lead away from the lateral pocket.
  • This method is more cost-effective since it uses the same device if the trial is successful. It also ensures that the leads remain in the same location if the SCS is permanently implanted.[rx]
• Permanent placement with paddle-type electrodes
  • This trial can take place via a percutaneous paddle introduction technique, which utilizes a wide flat introducer. It can also be implanted via a laminotomy, allowing the paddle to enter the epidural space. This approach is usually by neurosurgery, typically as a permanent step.[rx]
• Permanent percutaneous SCS implantation:
  • If using the permanent trial approach, the IPG incision is opened on the day of the implant.  The lead extension is cut, pulled out through the skin, and discarded. The permanent lead is attached to a new extension and connects to the IPG.
  • If the percutaneous trial was used, follow the same steps used for the trial approach on the day of the implantation procedure. The permanent lead is tunneled to an appropriately sized (for the IPG used) subcutaneous pocket, where the lead directly connects to the IPG device. The IPG is then placed in the pocket. The incisions are stapled and covered with a sterile dressing. The staples are removed in the clinic 14 days later.[rx]
  • When sizing the pocket, often, a radiopaque template can be used. Typical pocket locations are on either side, and either above or below the beltline. The laterality of the pocket is determined beforehand utilizing a variety of methods. Most commonly, location determination is by patient comfort, i.e., the side opposite of where he or she sleeps, or the side that the patient can reach better (for reprogramming or recharging).

The surgical decision

Determining whether a spinal cord stimulator will be a good option for you is a two-step process. First, you must undergo a temporary trial to see if the device decreases your level of pain.

Stage 1. Trial “test drive” – Trial stimulation is a “test drive” to determine if an SCS will work for the type, location, and severity of your pain. It is performed at an outpatient center. If you take blood-thinners, you are required to stop the medication 3 to 7 days prior to the trial. A local anesthetic is given to numb the area in the lower back. Using X-ray fluoroscopy, a hollow needle is inserted through the skin into the epidural space between the bone and spinal cord. The trial lead is inserted and positioned over specific nerves. The wires are attached to an exter­nal generator worn on a belt  You will be sent home with instructions on how to use the trial stimulator and care for your incision site. Keep a written log of the stimulation settings during different activities and the level of pain relief. After 4 to 7 days, you will return to the doctor’s office to discuss permanently implanting the stimulator or removing the trial leads.

Stage 2. Surgical implant  – If the trial is successful and you felt greater than 50% improvement in pain, surgery can be scheduled to implant the SCS device in your body.

What happens before surgery?

In the doctor’s office, you will sign consent and other forms so that the surgeon knows your medical history (allergies, medicines/vitamins, bleeding history, anesthesia reactions, previous surgeries). Inform your healthcare provider about all the medications (over-the-counter, prescription, herbal supplements) that you are taking. Presurgical tests (e.g., blood test, electrocardiogram, chest X-ray) may need to be done several days before surgery. Consult your primary care physician about stopping certain medications and ensure you are cleared for surgery.

Continue taking the medications your surgeon recommends. Stop taking all non-steroidal anti-inflammatory medicines (ibuprofen, naproxen, etc.) and blood thinners (Coumadin, aspirin, Plavix, etc.) 7 days before surgery. Stop using nicotine and drinking alcohol 1 week before and 2 weeks after surgery to avoid bleeding and healing problems.

You may be asked to wash your skin with Hibiclens (CHG) or Dial soap before surgery. It kills bacteria and reduces surgical site infections. (Avoid getting CHG in eyes, ears, nose or genital areas.)

Morning of surgery

• Don’t eat or drink after midnight before surgery (unless the hospital tells you otherwise). You may take permitted medicines with a small sip of water.
• Shower using antibacterial soap. Dress in freshly washed, loose-fitting clothing.
• Wear flat-heeled shoes with closed backs.
• Remove make-up, hairpins, contacts, body piercings, nail polish, etc.
• Leave all valuables and jewelry at home (including wedding bands).
• Bring a list of medications (prescriptions, over-the-counter, and herbal supplements) with dosages and the times of day usually taken.
• Bring a list of allergies to medication or foods.

Arrive at the hospital 2 hours before your scheduled surgery time (1 hour before at the outpatient surgery center) to complete the necessary paperwork and pre-procedure work-ups. An anesthesiologist will talk with you and explain the effects of anesthesia and its risks. An intravenous (IV) line will be placed in your arm.

What happens during surgery?

The surgery generally takes 1 to 2 hours.

• Step 1: prepare the patient  – You will lie on your stomach on the table and be given light anesthesia. Next, the areas of your back and buttock are prepped where the leads and generator are to be placed.
• Step 2: place the leads – The electrode leads are inserted with the aid of fluoroscopy (a type of X-ray). A small skin incision is made in the middle of your back, and the bony vertebra is exposed. A portion of the bony arch is removed (laminotomy) to allow room to place the leads. The leads are positioned in the epidural space above the spinal cord and secured with sutures. The leads do not directly touch your spinal cord.
• Step 3: test stimulation (optional) – Depending on the SCS device being implanted, you may be awakened to help the doctor test how well the stimulation covers your pain areas. However, modern SCS device leads can be positioned based on anatomy or electric monitoring of the nerves. Settings from the trial will be used to program the pulse generator at the end of the surgery, so your feedback is important to ensure the best pain relief. In some cases, if the leads implanted during the trial are positioned perfectly, there is no need to reposition or insert new leads.
• Step 4. tunnel the wire – Once the lead electrodes are in place, the wire is passed under the skin from the spine to the buttock, where the generator will be implanted.
• Step 5. place the pulse generator – A small skin incision is made below the waistline. The surgeon creates a pocket for the generator beneath the skin. The lead wire is attached to the pulse generator. The generator is then correctly positioned within the skin pocket.
• Step 6. close the incisions  – The incisions are closed with sutures and skin glue. A dressing is applied.

What happens after surgery?

You will wake up in the recovery area. Your blood pressure, heart rate, and respiration will be monitored, and your pain will be addressed. Most patients are discharged home the same day or the following morning. The pulse generator will be programmed before you leave. You will be given written instructions to follow when you go home.

Follow the surgeon’s home care instructions for 2 weeks after surgery or until your follow-up appointment. In general, you can expect:

Restrictions

Do not bend, lift, twist your back or reach overhead for the next 6 weeks. This is to prevent the leads from moving out of place until it heals.

• Don’t lift anything heavier than 5 pounds.
• No strenuous activity including yard work, housework and sex.
• Don’t drive until your follow-up appointment.
• Don’t drink alcohol. It thins the blood and increases the risk of bleeding. Also, don’t mix alcohol with pain medicines.

Incision Care

• Wash your hands thoroughly before and after cleaning your incision to prevent infection.
• You may shower the day after surgery.
• Gently wash the incision covered in Dermabond skin glue with soap and water every day. Don’t rub or pick at the glue. Pat dry.
• Don’t soak the incision in a bath or pool.
• Don’t apply lotion / ointment on the incision.
• If there is drainage, cover the incision with a dry gauze dressing. If drainage soaks through two or more dressings in a day, call the office.
• Some clear, pinkish drainage from the incision is normal. Watch for increased volume of drainage or spreading redness. An infected incision may have colored drainage and begin to separate.

Medications

• Take pain medication as directed by your surgeon. Reduce the amount and frequency as your pain subsides. If you don’t need the pain medicine, don’t take it.
• Narcotics can cause constipation. Drink lots of water and eat high-fiber foods. Stool softeners and laxatives can help move the bowels. Colace, Senokot, Dulcolax, and Miralax are over-the-counter options.

Activity

• Ice your incision 3-4 times per day for 15-20 minutes to reduce pain and swelling.
• Don’t sit or lie in one position longer than an hour unless you are sleeping. Stiffness leads to more pain.
• Spinal headaches may be caused by leakage of cerebrospinal fluid around the lead site. The leak often heals on it’s own. Lie flat and drink plenty of caffeinated non-carbonated fluids (tea, coffee).
• Get up and walk 5-10 minutes every 3-4 hours. Gradually increase walking, as you are able.

When to Call Your Doctor

• Fever over 101.5° F (unrelieved by Tylenol)
• Unrelieved nausea or vomiting.
• Severe unrelieved pain.
• Signs of incision infection.
• Rash or itching at the incision (allergy to Dermabond skin glue).
• Swelling and tenderness in the calf of one leg (sign of a blood clot).
• New onset of tingling, numbness, or weakness in the arms or legs.
• Dizziness, confusion, nausea or excessive sleepiness.
• Fluid may accumulate under the skin around the leads or the device, creating a visible swelling (seroma). Call the doctor if this occurs.
• Sudden severe back pain, sudden onset of leg weakness and spasm, loss of bladder and/or bowel function – this is an emergency – go to a hospital and call your surgeon.

Recovery

Approximately 10 days after surgery you will come to the office to have the incision checked. Bring your device remote and product box to your follow-up appointment with the surgeon. The programming of the pulse generator can be adjusted at this time if needed. It is important to work with your doctor to adjust your medications and refine the programming of the stimulator.

Your pain specialist and device representative will work with you to fine-tune adjustments to the SCS.

What are the results?

The results of SCS depend on careful patient selection, successful trial stimulation, proper surgical technique, and patient education. Stimulation does not cure the condition that is causing pain. Rather, it helps patients manage the pain. SCS is considered successful if pain is reduced by at least half.

Published studies of spinal cord stimulation show good to excellent long-term relief in 50 to 80% of patients suffering from chronic pain [1-6]. One study reports that 24% of patients improved sufficiently to return to gainful employment or housework with stimulation alone or with the addition of occasional oral pain medication [7].

SCS therapy is reversible. If a patient decides at any time to discontinue, the electrode wires and generator can all be removed.

Additional Disadvantages

Less serious disadvantages of spinal cord stimulation devices include:

• Fluctuations in stimulation. Unwanted changes in stimulation may include a jolting or shocking feeling. The device should be turned off and the doctor contacted if this occurs.
• Pain is not resolved. Spinal cord stimulation interferes with pain signals sent to the brain but does not treat the underlying condition. People using this therapy need to continue working with others on their health care team.
• Reaction to pressure. Those using spinal cord stimulation should not take part in activities that add pressure to the body. Scuba diving more than 10 meters below the surface should be avoided, and the doctor should be consulted before entering a hyperbaric chamber.
• Electromagnetic interference. Strong interference, such as from a defibrillator or MRI (if the spinal cord stimulation device is not MRI-safe), can damage the generator, leading to severe burns, another serious injury, or death. Skin irritation may develop near the generator related to charging.
• Discomfort around the generator. Some people find the implanted generator irritating or uncomfortable.

Relieving pain with spinal cord stimulation has some drawbacks. It is a different experience compared with painkillers or other pain control techniques. Learning as much as possible about spinal cord therapy can help a person decide on the best option to ease chronic pain in the back, neck, or limbs.

Complications of Spinal cord stimulation

• Complications associated with spinal cord stimulation span from correctable issues such as inappropriate paresthesia coverage to infection, epidural hematoma, nerve injury, paralysis, and death. Luckily, the more devastating complications are exceedingly rare. Infection is minimized by the use of sterile technique and operating room conditions. The risk of nerve injury and paralysis is mitigated by the use of continual fluoroscopy throughout the procedure with both trajectory and depth views. More serious complications related to oversedation, anesthesia, airway compromise, and anaphylactic reactions can be lowered and managed by licensed anesthesia professionals.
• The most common non-easily correctable problem is infection. Over the years, with proper quality control measures, the advancement of techniques, and perioperative antibiotics guidelines, the incidence of infection has declined to around 3%-5% depending on different sources.[rx] The most common infection is Staphylococcus, which is present in 18% of cases. The most common site of infection is the IPG site (54%).  In a vast majority of cases, infection requires explant of the entire system, unless the contamination is confined only to the superficial tissues.[rx]
• The most frequent complication overall is lead migration or breakage. This issue can be minimized by a restriction period of one to two months, where the patient limits bending, lifting, and twisting until the leads can scar down in the appropriate location.  As lead and anchor technology advances, the rate of revision due to lead migration continues to decline. Of note, the more rigid paddle leads are twice as likely to break than the percutaneous leads.[rx]

Clinical Significance

• In the United States, the most common clinical use of SCS therapy is failed back surgery syndrome. In Europe, the most common use of SCS therapy is peripheral ischemia.
• Clinical recommendations can be divided based on diagnosis

  1. Failed back surgery syndrome (FBSS) – level A recommendation

     1. Established as causing long-term pain relief, decreased medication use, increased functional capacity, improved quality of life, increased likelihood of returning to work, and minimal side effects when compared to other treatments.[rx]

        1. In a study by North et al., they looked at 27 patients with FBSS who were selected for a repeat laminectomy vs. SCC therapy. The study showed that 47% of the patients in the SCS group, while only 12% of the patients in the repeat laminectomy group, experienced over 50% pain relief. The study also showed that patients in the repeat laminectomy group used significantly more opioids than those in the SCS group.[rx]
        2. Another study by Kumar and colleagues followed FBSS patients treated with SCS therapy vs. FBSS patients treated with conventional medical management (CMM) for six months. The patients in this study mainly had neuropathic radicular lower extremity pain. The study showed that at six months, 24 SCS patients (48%) and only 4 CMM patients (9%) received over 50% pain relief from the treatment. The SCS therapy patients also reported relief of back and leg pain, improved quality of life, improved functional capacity, and more satisfaction from the treatment. The patients were also evaluated at 24 months, still showing increased satisfaction from SCS therapy.[rx]
  2. Complex regional pain syndrome (CRPS) – level B recommendation

     1. Established as increasing perceived effect, pain reduction, and quality of life. Even though some studies have suggested that the use of SCS therapy in patients with CRPS should be considered level A recommendation, the majority of the literature indicates that high-quality research is limited in this category.[rx]

        1. Kemler et al. conducted one of the studies available. It compared 24 patients with CRPS treated with combined permanent SCS therapy (after a successful trial) and physical therapy vs. 18 patients treated with physical therapy alone. After six months of follow-up, the patients in the SCS therapy group reported significant pain relief. They rated themselves as “much improved” when asked when compared to the physical therapy-only group. There were no differences in the reported improvements in functional status. The patients were re-evaluated after two years, showing the durability of these findings.[tx]
  3. Angina Pectoris – level A recommendation

     1. Established as decreasing anginal attacks, nitrate requirements, higher exercise capacity, cardiovascular outcomes equivalent to coronary bypass surgery

        1. Multiple studies have shown that SCS therapy can effectively treat intractable angina and decrease the incidence of anginal attacks. The primary mechanism that posited to explain this is by an increase in the skin temperature in the distal extremities during SCS therapy. The increased temperature improves the microcirculatory status of the extremity. As a result, there is an increase in the nutritional health of the skin and nerves in the area, leading to decreased anginal attacks.[rx] One way to measure microvascular perfusion in the extremities is by measuring the transcutaneous partial pressure of oxygen (TcPO2), which can be increased by either sympathetic blockade or SCS treatment.[rx]
        2. Numerous studies have concluded that SCS therapy can successfully treat refractory angina by increasing oxygen supply to the affected area, relieving the ischemia. In this procedure, the leads are placed at the level of T1-T2, left of the midline, and the leads are advanced to the level of the chest where patients report anginal pain. Studies have shown that the SCS provides a similar benefit and efficacy to coronary bypass surgery, with decreased morbidity and mortality in the acute setting. Despite the multiple studies favoring this form of treatment, SCS therapy has not received support in the field of cardiology.
  4. Peripheral ischemia – level A recommendation

     1. Ubbink and Vermeulen performed the main meta-analysis study regarding the effect of SCS therapy in patients with peripheral ischemia in 2006. They evaluated nine different studies, for a total of 444 patients. This study showed that patients who undergo SCS therapy have 11% less risk of having a limb amputation than those who only undergo conservative treatment. Patients treated with SCS therapy had improved quality of life and decreased pain medication use. This study also concluded that TcPO2 measurements of less than 10 mmHg increase the risk of amputation, while TcPO2 greater than 30 mmHg leads to improved outcomes, regardless of the treatment approach. The authors reported a TcPO2 increase of 10 mmHg or more with SCS therapy. The study concluded that patients have an 83% limb salvage rate with SCS therapy, as opposed to only 20% to 64% with conservative management [rx]. Other studies, however, have not been able to show any significant decrease in the risk of limb amputation in these patients.[rx]

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