Medical Policy: 07.01.61
Original Effective Date: November 2000
Reviewed: August 2016
Revised: September 2015
Benefit determinations are based on the applicable contract language in effect at the time the
services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary
based on contract, and individual member benefits must be verified. Wellmark determines medical
necessity only if the benefit exists and no contract exclusions are applicable. This medical
policy may not apply to FEP. Benefits are determined by the Federal Employee Program.
This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Spinal cord stimulation (SCS), also known as dorsal column stimulator (DCS) delivers a low voltage electrical current continuously to the dorsal columns of the spinal cord to block the sensation of pain. The neurophysiology of pain relief after SCS is uncertain but may be related to either activation of an inhibitory system or blockage of facilitative circuits. SCS is the most commonly used implantable neurostimulation technology for the management of pain syndromes.
SCS is used for the treatment of pain that is neuropathic in nature, i.e. resulting from damage to the peripheral nerves. Common indications include, but are not limited to failed back syndrome (lumbar or cervical), complex regional pain syndrome (i.e. reflex sympathetic dystrophy), arachnoiditis, radiculopathies, phantom limb/stump pain and peripheral neuropathy. There has been an interest in SCS as a treatment of critical limb ischemia, primarily in patients who are poor candidates for revascularization and in patients with refractory chest pain.
Spinal cord stimulation (SCS) devices consists of several components: (1) the lead that delivers the electrical stimulation to the spinal cord; (2) an extension wire that conducts the electrical stimulation from the power source to the lead; and (3) a power source that generates the electrical stimulation. The lead may incorporate 4 to 8 electrodes, with 8 electrodes more commonly used for complex pain patterns. The patient’s pain distribution pattern dictates at what level in the spinal cord the stimulation lead is placed. The pain pattern may influence the type of device used; for example, a lead with 8 electrodes may be selected for those with complex pain patterns or bilateral pain. Totally implantable systems are the most commonly used.
Traditional spinal cord stimulation devices use electrical stimulation with a frequency on the order of 100 to 1000 HZ. Some devices allow adjustment of the frequency settings. At least 1 newer device is available that uses higher frequency stimulation (10,000) HZ. The high-frequency stimulation is proposed to be associated with fewer paresthesias, which are a recognized effect of traditional spinal cord stimulation devices.
Types of Spinal Cord Stimulation Devices:
Patients being considered for spinal cord stimulation should ideally meet the following criteria:
Spinal cord stimulation is used only as a last resort; other treatment modalities (pharmacological, surgical, psychological or physical, if applicable) have been tried and failed or are judged to be unsuitable or contraindicated.
Implantation of the spinal cord stimulator device is typically a 2 step process:
Spinal Cord Stimulator Trial
The first step is to implant a device on a trial basis which is done in an outpatient visit. The patient’s skin is numbed with a local anesthetic; leads are placed under the skin and attached to a small generator that the patient carries (much like a pager or cell phone); and using pre-set programs, electrical currents are emitted in a pattern to target the areas of pain. The trial phase can be beneficial for the following reasons:
The individual will keep a written log of the stimulation settings during different activities, along with the level of pain relief. If the trial is successful (reduction in pain of at least 50% or more) then a permanent spinal cord stimulator may be implanted.
Permanent Spinal Cord Stimulator
If the SCS trial provides adequate pain relief (demonstrates a reduction in pain of at least 50% or more during the trial period), then a permanent system may be implanted. Documentation of the reduction of pain should be based on objective evidence of pain relief (e.g. decreased opioid usage, improved range of motion of the affected area, increased activity, increased pain relief according to the Visual Analog Scale (VAS) of the Numeric Pain Intensity Scale).
The trial electrodes are often removed, and implantation of new electrodes and the pulse generator are performed as a separate procedure. The electrode placement for implantation may be performed by laminotomy or percutaneous approach. A small incision is made to allow insertion of epidural needles, anchoring of the leads after insertion, and tunneling of the lead extension cable. The leads are placed by fluoroscopy and tested for paresthesia. After stimulation is programmed, the level of sedation can be deepened as appropriate for generator placement. A second incision is made to create the pocket for the implantable pulse generator (IPG). The generator is usually implanted in the abdomen or buttock region. The extension cable must be tunneled under the skin between the lead connector and the IPG.
On rare occasions, surgical revisions may be needed if the neurostimulator electrodes migrate or move from the area needing stimulation. Also, if the individual is unable to tolerate the electrodes, the individual has an onset of neurological deficits, the modality itself becomes ineffective over time, or, if the leads and/or pulse generator become infected, the device may be removed. In addition, if an individual develops certain medical conditions (e.g. severely impaired left ventricular function) that cause a need for an automatic implantable cardioverter defibrillator (AICD), this may necessitate the removal of the SCS device because the SCS signals may be falsely interpreted by the AICD.
Indications for Spinal Cord Stimulation (SCS)
Chronic Limb or Trunk Pain
The evidence on the efficacy of SCS for the treatment of chronic limb or truck pain consists of a small number of small RCTs that include patients with refractory pain due to conditions such as failed back surgery and CRPS (reflex sympathetic dystrophy) and diabetic neuropathy. SCS is not designed to treat the underlying conditions, but rather the symptoms; therefore grouping the conditions is reasonable. These studies are heterogenous in terms of patient populations and outcomes, and participants were not blinded (no studies used sham surgeries or devices) but consistently report an improvement in pain and a reduction in requirement of medications for at least 6 months. Even with sham surgery or device, blinded outcomes assessment may not be feasible for SCS because active SCS stimulation is associated with paresthesias. Given the large treatment effects with consistent findings across studies, this evidence suggests that SCS is a reasonable treatment option.
Critical Limb Ischemia
Critical limb ischemia is described as pain at rest or the presence of ischemic limb lesions. If the patients are not suitable candidates for limb revascularization (typically due to insufficient distal runoff), amputation may be required in a substantial number of patients. SCS has been investigated in this subset of patients as a technique to relieve pain and decrease incidence of amputation.
Based on the literature there are a number of relatively small RCTs for SCS versus usual care that have been completed on patients with critical limb ischemia. SCS did not result in a significantly lower rate of amputation and therefore, the evidence is not sufficient to conclude that SCS improves outcomes for patients with critical limb ischemia and is considered investigational.
Refractory Angina Pectoris
Spinal cord stimulation (SCS) has been used to treat refractory angina in Europe and much of the literature on SCS comes from European centers. Numerous small RCTs have evaluated SCS as a treatment for refractory angina. Some studies have reported a benefit, the majority have not. More recent RCTs that enrolled more than 100 patients, there was no benefit on the primary outcomes. Overall, this evidence is mixed and not sufficient to allow conclusions on whether health outcomes are improved and therefore, would be considered investigational.
Findings of a small pilot crossover RCT evaluating SCS for heart failure were published in 2014 by Torre-Amione et al. Eligibility included symptomatic heart failure despite optimal medical therapy, left ventricular ejection fraction less than 30%, hospitalization or need for intravenous inotropic support in the past year, and ability to walk less than 450 meters on a 6-minute walk test. All patients had an implanted heart device. Nine patients underwent SCS implantation and received 3 months of active treatment and 3 months of inactive treatment (off position), in random order. There was a 1-month washout period between treatments. The primary outcome was a composite of death, hospitalization for worsening heart failure, and symptomatic bradyarrhythmia or tachyarrhythmia requiring high-voltage therapy. Four patients experienced at least 1 of the events in the composite end point. The event occurred in 2 patients while the device was turned on and 2 while it was turned off. One patient died about 2 months after implantation while the device was turned off. The SCS devices did not interfere with the functioning of implantable cardioverter defibrillators. Additional RCTs with larger sample sizes and longer follow-up are needed to draw conclusions on the safety and effectiveness of the therapy for this indication and therefore, would be considered investigational.
The evidence for SCS in individuals with critical limb ischemia or refractory angina pectoris or heart failure includes RCTs. However, available RCTs have not consistently demonstrated a benefit associated with SCS treatment. The evidence is insufficient to determine the effects of health outcomes and therefore is considered investigational.
Cancer Related Pain
In a 2013, a Cochrane review was published on SCS for treatment of cancer related pain in adults. The author did not identify any RCTs evaluating the efficacy of SCS in patients with cancer related pain. Four case series using a before-after design with a total of 92 patients were identified. However, in the absence of controlled studies, the evidence is insufficient to determine the effects on health outcomes for SCS in the treatment of cancer related pain and is considered investigational.
Nociceptive Pain and Central Deafferentation Pain
Based on the peer reviewed literature spinal cord stimulation is generally not effective in treating nociceptive (pain which results from irritation, not damage to the nerves), or for central deafferentation pain (related to central nervous system damage from a stroke or spinal cord injury). The use of spinal cord stimulation for these indications would be considered investigational.
For all other potential indications, there is insufficient evidence from controlled trials to conclude that SCS improves the net health outcome and therefore, SCS is considered investigational.
Practice Guideline and Position Statements
National Institute of Health and Clinical Excellence (NICE)In October 2008, The National Institute for Health and Clinical Excellence (NICE) issued a guideline on spinal cord stimulation for chronic pain of neuropathic or ischemic origin. The guideline stated that SCS is recommended as a treatment option for adults with chronic pain of neuropathic origin who continue to experience pain chronic pain (measuring at 50 mm on a 0-100 mm VAS) for at least 6 months despite appropriate conventional medical management, and who have had a successful trial of stimulation as part of an assessment by a specialist team.
Spinal cord stimulation is not recommended as a treatment option for adults with chronic pain of ischemic origin except in the context of research as part of a clinical trial.
American Society of Interventional Pain hysicians (ASIPP)
In 2013, The American Society of Interventional Pain Physicians updated their evidence based guidelines for interventional techniques in the management of chronic spinal pain. The guidelines included the statement that there is fair evidence in support of SCS in managing patients with failed back syndrome.
Neuropathic Pain Special Interest Group of the International Association for the Study of Pain: In 2013, the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain published recommendations on management of neuropathic pain. The interest group issued 2 recommendations on SCS; both were considered weak due to the amount and consistency of the evidence. The recommendations supported the use of SCS for failed back surgery syndrome and for complex regional pain syndrome (CRPS).
Permanently implanted spinal cord stimulator devices are approved for marketing by the U.S. Food and Drug Administration (FDA) under the premarket approval (PMA) process; temporary devices used to determine a patient’s eligibility for a permanent implant are cleard under the 510(k) premarket notification process.
In May 2015, FDA approved the Nevro SenzaTM Spinal Cord Stimulator (Nevro Corp. Menlo Park, CA), a totally implantable neurostimulator device, for the following indications: “chronic intractable pain of the truck and/or limbs, including unilateral or bilateral pain associated with the following: failed back surgery syndrome, intractable low back pain, and leg pain.” This device uses a higher frequency of electrical stimulation (10 kHz) than standard devices.
Implantation of a Temporary (Trial) Spinal Cord Stimulation (SCS) Device
A trial period using a temporary spinal cord stimulator device may be considered medically necessary when all of the following criteria are met:
An individual has undergone careful screening, including evaluation by a multi-disciplinary team that confirms the existence of one of the following conditions:
Documentation in the medical record of the failure of 6 months of conservative treatment modalities (pharmacologic, surgical, psychological or physical therapies), if appropriate and not contraindicated; and
Further surgical intervention is not indicated; and
Psychological evaluation has been obtained and there is documentation stating the pain is not psychologic in origin; and
There is no evidence of existing untreated drug addiction; and
No contraindications to implantation exist (i.e. sepsis or coagulopathy issues).
Implantation of Permanent Spinal Cord Stimulation (SCS) Device
Placement of a permanent spinal cord stimulator device may be considered medically necessary when the above medical necessity criteria for a trial placement of spinal cord stimulation are met, and the patient has demonstrated the following:
Replacement of Spinal Cord Stimulator Device
Replacement of spinal cord stimulator and/or battery/generator may be considered medically necessary for an individual that meets the above medical necessity criteria and the existing stimulator and/or battery/generator are/is no longer under warranty and cannot be repaired.
Removal or Revision of Spinal Cord Stimulator Device
The removal or revision of a spinal cord stimulator device may be considered medically necessary for any of the following indications:
Spinal cord stimulation is considered investigational for all other indications including but not limited to the following because the safety and effectiveness cannot be established by review of the available published peer reviewed literature:
Arachnoiditis: Painful condition caused by inflammation of the arachnoid, one of the three linings that surround and protect the brain and the spinal cord. The arachnoid can become inflamed due to a variety of reasons. These include irritation from chemicals present myelograms and epidural steroid injections; bacterial or viral infections; spinal cord injury; or complications from spinal surgery or other invasive spinal procedures. When arachnoiditis begins to impact the nerves, it can cause a number of symptoms, including numbness, tingling, and a distinctive stinging and burning pain the lower back and legs. Other symptoms may include debilitating muscle crams, twitches, spasms and bladder/bowel/sexual dysfunction. There is no cure for this condition, so the goal of treatment is to control pain and symptoms.
Arachnoiditis is usually documented by the presence of high levels of proteins in the cerebrospinal fluid and/or by myelography or magnetic resonance imaging.
Complex Regional Pain Syndrome (CRPS): Is an uncommon nerve disorder which causes intense burning pain, usually in the arms, hands, legs or feet. It can occur after an injury, either to a nerve or to tissue in the affected area. Along with pain, the patient may experience extreme skin sensitivity and changes in color, temperature or moistness of the skin. The cause of CRPS is unknown, and there is no cure.
Failed Back Syndrome (FBSS) or post laminectomy syndrome (lumbar or cervical):
Is persistent or recurrent pain, mainly involving the lower back and/or legs, even after prior anatomically successful spinal surgery. FBSS is considered a diagnosis of exclusion, so CT scans or MRIs must demonstrate that there are no surgically correctable lesions present. Patients with FBSS often have epidural/intraneural/perineural fibrosis or scar tissue, which generally will not respond to surgery but may respond to spinal cord stimulator (SCS).
Neuropathic Pain: Otherwise known as “nerve pain” is a complex, chronic pain state that usually is accompanied by tissue injury. With neuropathic pain, the nerve fibers themselves might be damaged, dysfunctional or injured. These damaged nerve fibers send incorrect signals to other pain centers. The impact of nerve fiber injury includes a change in nerve function both at the site of injury and areas around the injury.
Nociceptive Pain: Nociceptors are the nerves which sense and respond to parts of the body which suffer from damage. They signal tissue irritation, impending injury or actual injury. When activated they transmit pain signals (via the peripheral nerves as wella s the spinal cord) to the brain. The pain is typically well localized, constant and often with an aching throbbing quality. Visceral pain is the subtype of nociceptive pain that involves the internal organs. It tends to be episodic and poorly localized.
Nociceptive pain is usually time limited, meaning when the tissue damage heals, the pain typically resolves.
Central Deafferentation Pain: Central pain is defined as pain that is initiated by a primary lesion within the CNS. Central pain can occur in association with all types of CNS lesions related to wide variety of pathological processes. Deafferentation pain denotes a type of pain that results from complete or partial interruption of afferent nerve impulses. This type of pain results from lesions that interrupt the spinothalmic pathways at any level of the nervous system.
Patients with deafferentation pain usually display varying degrees of sensory loss characterized by disturbances with pain and temperature sensation.
Critical Limb Ischemia (CLI): Is a severe blockage in the arteries of the lower extremities, which markedly reduces blood-flow. It is a serious form of peripheral arterial disease, or PAD. CLI is a chronic condition that results in severe pain in the feet or toes, even while resting. Complications of poor circulation can include sores and wounds that won't heal in the legs and feet. Left untreated, the complications of CLI will result in amputation of the affected limb.
Refractory Angina Pectoris: Is a chronic condition characterized by the presence of angina caused by coronary insufficiency in the presence of coronary artery disease which cannot be controlled by a combination of medical therapy, angioplasty and coronary bypass surgery. The presence of reversible myocardial ischemia should be clinically established to be the cause of the symptoms. Chronic is defined as a duration of more than 3 months.
Ischemic Pain: Is caused by a reduction in oxygen delivery to the tissue, usually caused by reductive in blood flow because of construction of blood vessel (vasospasm) or its obstruction by atheroma or embolus. Ischemic pain conditions include critical limb ischemia & refractory angina).
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