Spinal cord stimulation delivers low voltage electrical stimulation to the dorsal columns of the spinal cord to block the sensation of pain. The neurophysiology of pain relief after spinal cord stimulation is uncertain, but may be related to either activation of an inhibitory system or blockage of facilitative circuits. Spinal cord stimulation devices consist 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 from 4 to 8 electrodes, with 8 electrodes more commonly used for complex pain patterns, such as bilateral pain or pain extending from the limbs to the trunk. There are 2 basic types of power source. In one type the power source (battery) can be surgically implanted. In another a radiofrequency receiver is implanted, and the power source is worn externally with an antenna over the receiver. Totally implantable systems are most commonly used.

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. Implantation of the spinal cord stimulator is typically a 2-step process. Initially, the electrode is temporarily implanted in the epidural space, allowing a trial period of stimulation. Once treatment effectiveness is confirmed, defined as at least 50% reduction in pain, the electrodes and radio-receiver/transducer are permanently implanted. Successful spinal cord stimulation may require extensive programming of the neurostimulators to identify the optimal electrode combinations and stimulation channels. Computer-controlled programs are often used to assist the physician in studying the millions of programming options when complex systems are used.

Spinal cord stimulation has been used in a wide variety of chronic refractory pain conditions, including pain associated with cancer, failed back pain syndromes, arachnoiditis, and  complex regional pain syndrome (i.e, chronic reflex sympathetic dystrophy). There has also been interest in spinal cord stimulation as a treatment of critical limb ischemia, primarily in patients who are poor candidates for revascularization, and in patients with refractory chest pain.

Note: Deep brain stimulation of the thalamus, globus pallidus, or subthalamic nuclei as a treatment of tremor or Parkinson’s disease is addressed in a separate policy, No. 7.01.63.

Spinal cord stimulation may be considered medically necessary for the treatment of severe and chronic pain of the trunk or limbs that is refractory to all other pain therapies.

Spinal cord stimulation is considered investigational as a treatment of critical limb ischemia as a technique to forestall amputation and as a treatment for refractory angina pectoris.

Patient selection focuses on determining whether or not the patient is refractory to other types of treatment. The following considerations may apply.

• The treatment 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;
• Pain is neuropathic in nature; i.e., resulting from actual damage to the peripheral nerves. Common indications include, but are not limited to failed back syndrome, complex regional pain syndrome (i.e., reflex sympathetic dystrophy), arachnoiditis, radiculopathies, phantom limb/stump pain, peripheral neuropathy. Spinal cord stimulation is generally not effective in treating nociceptive pain (resulting from irritation, not damage to the nerves) and central deafferentation pain (related to CNS damage from a stroke or spinal cord injury).
• No serious untreated drug habituation exists;
• Demonstration of at least 50% pain relief with a temporarily implanted electrode precedes permanent implantation;
• All the facilities, equipment, and professional and support personnel required for the proper diagnosis, treatment, and follow-up of the patient are available.

CPT codes for programming spinal cord stimulators are defined as follows:

95970: Electronic analysis of implanted neurostimulator pulse generator system (e.g., rate, pulse amplitude and duration, configuration of wave form, battery status, electrode selectability, output modulation, cycling, impedance and patient compliance measurements); simple or complex brain, spinal cord, or peripheral (i.e., cranial nerve, peripheral nerve, autonomic nerve, neuromuscular) neurostimulator pulse generator/transmitter, without reprogramming

95971: simple spinal cord, or peripheral (i.e., peripheral nerve, autonomic nerve, neuromuscular) neurostimulator pulse generator/transmitter, with intraoperative or subsequent programming

95972: complex spinal cord, or peripheral (except cranial nerve) neurostimulator pulse generator/transmitter, with intraoperative subsequent programming, first hour

95973: complex spinal cord, or peripheral (except cranial nerve) neurostimulator pulse generator/transmitter, with intraoperative subsequent programming, each additional 30 minutes after first hour

BlueCard/National Account Issues

Patients with chronic refractory pain may be managed through case management programs.

State or federal mandates (e.g., FEP) may dictate that all devices approved by the U.S. Food and Drug Administration (FDA) may not be considered investigational. Therefore, FDA-approved devices may be assessed on the basis of their medical necessity.

The bulk of published literature regarding spinal cord stimulation (SCS) consists of case series. In a systematic literature synthesis of these studies, Turner and colleagues reported that in patients with chronic low back pain, an average of 59% of patients had 50% or greater pain relief. (1)

Preliminary results of a randomized controlled trial reported that a significantly greater proportion of patients initially randomized to repeat lumbosacral surgery opted to cross over to the spinal cord stimulation arm of the trial, compared to those initially in the spinal cord stimulation of the trial crossing over to lumbosacral surgery. (2) A prospective multicenter study of spinal cord stimulation in 219 patients with chronic back and extremity pain reported successful management of pain in 55% of patients. (3) Most recently, Kemler and colleagues reported on favorable outcomes of SCS among patients with chronic reflex sympathetic dystrophy who were randomized to the SCS arm, as compared to those treated with physical therapy alone. (4) The favorable outcomes were still present at 2 years’ follow-up. (5)

2005 Update

A literature search was performed on the MEDLINE database for the period of 1998 through June 2005, with a specific focus on spinal cord stimulation (SCS) as a treatment of limb ischemia.

Critical limb ischemia is described as pain at rest or the presence of ischemic limb lesions. If the patient is not a suitable candidate for limb revascularization (typically due to insufficient distal runoff), it is estimated that amputation will be required in 60%–80% of these patients within a year. Spinal cord stimulation has been investigated in this small subset of patients as a technique to relieve pain and decrease the incidence of amputation. Klomp and colleagues conducted a study that randomized 120 patients with critical limb ischemia not suitable for vascular reconstruction to undergo either best medical care or medical care in addition to spinal cord stimulation. The primary endpoint was limb survival at 2 years. (6) Amputation-free survival was not improved nor was the risk of major amputation significantly reduced. Both groups also reported similar levels of pain reduction. In both groups, the rates of amputation were highest within the first 3 months of the study, reflecting the limitations with both treatment options.

2006 Update

A search of the MEDLINE database was performed for the period of January 2005 through September 2006 with a focus on SCS as a treatment of limb ischemia. There are no new clinical studies on this topic.

A systematic review from the Cochrane group on use in peripheral vascular diseases was updated in 2005. Included were 6 European studies of generally good quality with a total of 444 patients. (7) None of the studies were blinded due to the nature of the treatment. At 12 months’ follow-up, limb salvage improved by 11% compared with any form of conservative treatment with a number needed to treat (NNT) of 9. The SCS patients required significantly less analgesics, and more patients reached Fontaine stage II than in the conservative group. There was no difference in ulcer healing. The overall risk of complications or additional SCS treatment was 17%, with a number needed to harm (NNH) of 6. The report concludes that there is evidence to favor SCS over standard conservative treatment to improve salvage and clinical situation in patients with critical leg ischemia and that, “The benefits of SCS against the possible harm of relatively mild complications and costs must be considered.” Analysis of data and cost calculations from a previously published study (6) showed that the difference in amputation rate at 12 months was no longer present at 24 months. (8) There was no difference in survival rate at 24 months.

Evidence supports a decrease in pain with a short-term decrease in limb amputations following treatment with SCS. Complications include the need for operative repositioning procedures. There is no scientific evidence for improvement in pain and limb salvage at an endpoint of 24 months.

The use of SCS for other conditions such as visceral pain has been reported. The British Pain Society recommends that its use in this and other emerging indications be carefully audited (9).

2007-2008 Update
A search of the MEDLINE database was performed for the period of October 2006 through January 2008. A multicenter randomized trial (the PROCESS study) compared SCS (plus conventional medical management) with medical management alone in 100 patients with failed back surgery syndrome. (10) Leg painrelief(>50%), at 6 months was observed in 24 (48%) SCS-treated patients and 4 (9%) controls, with an average leg pain visual analog scale (VAS) score of 40 in the SCS group and 67 in the conventional management control group. Between 6 and 12 months, 5 (10%) patients in the SCS group and 32 (73%) patients in the control group crossed over to the other condition. Of the 84 patients who where implanted with a stimulator over the 12 months of the study, 27 (32%) experienced device-related complications. Another study reported 5-year outcomes from a randomized trial of 54 patients with complex regional pain syndrome (CRPS). (11) Twenty-four of the 36 patients assigned to SCS and physical therapy were implanted with a permanent stimulator after successful test stimulation; 18 patients were assigned to physical therapy alone. Five-year follow-up showed a 2.5 cm change in VAS pain score in the SCS group (n=20), and a 1.0 cm change for the control group (n=13),. Pain relief at 5 years was not significantly different between the groups; 19 (95%) patients reported that for the same result they would undergo the treatment again. Ten (42%) patients underwent reoperation due to complications.
An evidence-based review from the American Society of Pain Physicians found the evidence for SCS in failed back surgery syndrome and complex regional pain syndrome strong for short-term relief and moderate for long-term relief. (12) Reported complications with spinal cord stimulation ranged from infection, hematoma, nerve damage, lack of appropriate paraesthesia coverage, paralysis, nerve injury, and death.
Evidence-based guidelines from the European Federation of Neurological Societies found level B (i.e., at least one prospective matched-group cohort study or randomized controlled trial in a representative population) evidence for the effectiveness of SCS in failed back surgery syndrome and CRPS I. (13) The task force indicated that implantable stimulators are typically used when all other treatments have failed, and that this context should be taken into account when making recommendations.

2009 Update
The policy was updated with a literature review using MEDLINE through November 2008. This update focused on use of spinal cord stimulation (SCC) in the treatment of refractory angina pectoris.
The National Institute for Health and Clinical Excellence (NICE) states in NICE Guidance issued in October 2008 that spinal cord stimulation is recommended as a treatment option for adults with chronic pain of neuropathic origin who continue to experience chronic pain (measuring at least 50 mm on a 0–100 mm visual analog scale) 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.(14)
Refractory Angina
Spinal cord stimulation (SCS) has been used for treatment of refractory angina in Europe for 20 years and much of the literature on SCS comes from European centers. A systematic review of the literature based on the Swedish Council on Technology Assessment in Health Care report on long-standing pain was revised with an updated literature review and the conclusions published in 2008. (15) Seven controlled studies (5 of them randomized), 2 follow-up reports, and a preliminary report as well as 2 non-randomized studies determined to be of medium-to-high quality were included in the review. The largest randomized controlled trial (RCT) included 104 subjects and compared SCS and coronary artery bypass graft (CABG) in patients accepted for CABG and who were considered to have only symptomatic indication (i.e., no prognostic benefit) for CABG according to the American College of Cardiology/American Heart Association guidelines, to run an increased risk of surgical complications, and to be unsuitable for percutaneous transluminal coronary angioplasty. Between group differences on nitrate consumption, anginal attack frequency, and self-estimated treatment effect were not statistically significant at 6-months follow-up. (16) At 5-year follow-up, significantly fewer patients in the CABG group were taking long-acting nitrates, and between group differences on quality of life and mortality were not significant. (17) McNab compared SCS and percutaneous myocardial revascularization (PMR) in a study with 68 subjects. (Note: PMR is currently considered investigational through MPRM review.) Thirty subjects in each group completed 12-month follow-up, and differences on mean total exercise time and mean time to angina were not significant. Eleven in the SCS group and 10 in the PMR group had no angina during exercise. (18) The remaining RCTs included in the systematic review included 25 or fewer subjects. Two studies by De Jongste and others are included in the review. One, a 1993 report of preliminary results with 24 subjects is described as placebo controlled, however an abstract of the paper indicates that the treatment group received the stimulator within 2 weeks of randomization and the control group was implanted 8 weeks after the 2-month study period. (19) The later paper reports on a similar study with 17 patients. (20) A third paper by De Jongste not referenced in the review does describe a study in which 10 patients had 48-hour ambulatory electrocardiograhic (ECG) monitoring before and after SCS implantation. (21) In an RCT reported by Hautvast et al., 25 patients were randomized to SCS or standard treatment and followed for 6 weeks. The authors report significant differences exercise capacity and ischemia, frequency of anginal attacks, nitrate consumption, and quality of life. (22) A pilot RCT by Eddicks compared SCS and standard treatment; 12 patients were already receiving SCS and considered responders were randomized to receive SCS at 3 different stimulation timing and output parameters or to placebo (low output) for 4-week intervals. Randomization to and treatment for 4 weeks at the newly assigned regimen was then repeated 3 times. (23) The authors of the systematic review note the possibility of bias in studies of interventions that are difficult to blind, with small numbers of subjects, and not always randomized. They conclude, however, that there is strong evidence that SCS provides symptomatic benefits and improved quality of life for refractory angina.
Bondesson et al. report a study comparing SCS with enhanced external counterpulsation (EECP). One-hundred-fifty-three patients with refractory angina pectoris were identified and TENS (transcutaneous electrical nerve stimulation) was used to test tolerance to electrical stimulation (except those contraindicated by unipolar pacemaker). Forty-four patients had total symptom relief and were implanted with SCS. The 79 nonresponders underwent EECP. A control group consisted of 30 patients for whom SCS or EECP were contraindicated or who were unwilling to have either treatment. Outcome measures were Canadian Cardiovascular Society Class (CCS-class) and glyceryl trinitrate (GTN) usage. At 12 months, EECP reduced CCS-class from class 3 (marked limitation in activity, angina may occur after walking one block) to class 2 (slight limitation, angina may occur after walking two blocks) and 23% of the EECP group improved by 2 CCS classes. SCS reduced angina less, but the reduction was reported to be clinically significant. Of study patients who used GTN (all but 7%), decrease in weekly use was 67% of patients in the EECP group and 76% in the SCS group. The authors conclude that EECP can be used as an alternative treatment for patients not responding to electrical stimulation. That patients were not randomly assigned to treatment group and could not be blinded to treatment group with potential placebo effect are limitations of the study. (24)
Recent NICE Guidance states that “the committee noted that no studies had demonstrated statistically significant differences for pain outcomes, but that for refractory angina the effect of SCS had been shown to be comparable to other treatments, such as CABG and PCI, for functional outcomes. In addition, the Committee considered that there was some evidence of reduced medication use from studies of refractory angina.” The guidance concludes that “Spinal cord stimulation is not recommended as a treatment option for adults with chronic pain of ischaemic origin except in the context of research as part of a clinical trial. Such research should be designed to generate robust evidence about the benefits of spinal cord stimulation (including pain relief, functional outcomes and quality of life) compared with standard care. (14)
The European Society of Cardiology (ESC) guidelines on management of stable angina pectoris do not include SCS in its list of conclusions and recommendations but state that transcutaneous electrical stimulation and SCS are “well established methods used for the management of refractory angina. Patients experience a favorable analgesic effect and positive effects on symptoms when treated with SCS. A significant increase in the average exercise time has been demonstrated on treadmill testing.” They also point out that the available clinical trials are small and long-term effects are unknown. (24)
The British Pain Society 2005 recommendations for clinical practice state that “there is good quality evidence that SCS can be effective for patients with refractory angina pectoris.” (9)
The available evidence consists of case series and small controlled trials with methodological limitations and limited follow-up; and is not sufficient to conclude that SCS improves health outcomes for patients with refractory angina pectoris. Thus, this is indication is considered investigational.

Medicare Coverage

According to Medicare policy, the implantation of central nervous system stimulators may be covered as therapies for the relief of chronic intractable pain, subject to the following conditions:

• The implantation of the stimulator is used only as a late resort (if not last resort) for patients with chronic intractable pain;
• With respect to item a, other treatment modalities (pharmacological, surgical, physical or psychological therapies) have been tried and did not prove satidfactory, or are judged to be unsuitable or contraindicated for the given patient;
• Patients have undergone careful screening, evaluation and diagnosis by a multidisciplinary team prior to implantation. (Such screening must include psychological, as well as physical evaluation);
• All the facilities, equipment, and professional and support personnel required for the proper diagnosis, treatment training, and followup of the patient (including that required to satisfy item c) must be available; and
• Demonstration of pain relief with a temporary implanted electrode precedes permanent implantation.

References:

1. Turner JA, Loeser JD, Bell KG. Spinal cord stimulation for chronic low back pain: a systematic literature synthesis. Neurosurgery 1995; 37(6):1088-96.
2. Burchiel KJ, Anderson VC, Brown FD et al. Prospective, multicenter study of spinal cord stimulation for relief of chronic back and extremity pain. Spine 1996; 21(23):2786-94.
3. North RB, Kidd DH, Lee MS et al. A prospective, randomized study of spinal cord stimulation versus reoperation for failed back surgery syndrome: initial results. Stereotact Funct Neurosurg 1994; 62(1-4):267-72.
4. Kemler MA, Barendse GA, van Kleef M et al. Spinal cord stimulation in patients with chronic reflex sympathetic dystrophy. N Engl J Med 2000; 343(9):618-24.
5. Kemler MA, De Vet HC, Barendse GA et al. The effect of spinal cord stimulation in patients with chronic reflex sympathetic dystrophy: two years’ follow-up of the randomized controlled trial. Ann Neurol 2004; 55(1):13-8.
6. Klomp HM, Spincemaille GH, Steyerberg EW et al. Spinal cord stimulation in critical limb ischemia: a randomized trial. Lancet 1999; 353(9158):1040-4.
7. Ubbink DT, Vermeulen H. Spinal cord stimulation for non-reconstructable chronic critical leg ischaemia. Cochrane Database Syst Rev 2005; 3:CD004001.
8. Klomp HM, Steyerberg EW, van Urk H et al. ESES Study Group. Spinal cord stimulation is not cost-effective for non-surgical management of critical limb ischaemia. Eur J Vasc Endovasc Surg. 2006; 31(5):500-8.
9. The British Pain Society. Spinal cord stimulation for the management of chronic pain: Recommendations for best clinical practice. http://www.britishpainsociety.org/SCS_2005.pdf.
10. Kumar K, Taylor RS, Jacques L et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicentre randomised controlled trial in patients with failed back surgery syndrome. Pain 2007; 132(1-2):179-88.
11. Kemler MA, de Vet HC, Barendse GA et al. Effect of spinal cord stimulation for chronic complex regional pain syndrome type I: five-year final follow-up of patients in a randomized controlled trial. J Neurosurg 2008; 108(2):292-8.
12. Boswell MV, Trescot AM, Datta S et al; American Society of Interventional Pain Physicians. Interventional techniques: evidence-based practice guidelines in the management of chronic spinal pain. Pain Physician 2007; 10(1):7-111.
13. Cruccu G, Aziz TZ, Garcia-Larrea L et al. EFNS guidelines on neurostimulation therapy for neuropathic pain. Eur J Neurol 2007; 14(9):952-70.
14. National Institute for Health and Clinical Excellence (NICE). Spinal cord stimulation for chronic pain of neuropathic or ischaemic origin. NICE Technology Appraisal Guidance 159. October 2008. Accessible at http://www.nice.org.uk/Guidance/TA159.
15. Börjesson M, Andrell P, Lundberg D et al. Spinal cord stimulation in severe angina pectoris – A systematic review based on the Swedish Council on Technology Assessment in Health Care report on long-standing pain. Pain 2008 Nov 10 [Epub ahead of print].
16. Mannheimer C, Eliasson T, Augustinsson LE et al. Electrical stimulation versus coronary artery bypass surgery in severe angina pectoris: the ESBY study. Circulation 1998; 97(12):1157-63.
17. Ekre O, Eliasson T, Norrsell H et al. Long-term effects of spinal cord stimulation and coronary artery bypass grafting on quality of life and survival in the ESBY study. Eur Heart J 2002; 23(24):1938-45.
18. McNab D, Khan SN, Sarples LD et al. An open label, single-centre, randomized trial of spinal cord stimulation vs. percutaneous myocardial laser revascularization in patients with refractory angina pectoris: the SPiRiT trial. Eur Heart J 2006; 27(9):1048-53.
19. de Jongste MJ, Staal MJ. Preliminary results of a randomized study on the clinical efficacy of spinal cord stimulation for refractory severe angina pectoris. Acta Neurochir Suppl (Wien) 1993; 58:161-4.
20. de Jongste MJ, Hautvast RW, Hillege HL et al. Efficacy of spinal cord stimulation as adjuvant therapy for intractable angina pectoris: a prospective, randomized clinical study. Working Group on Neurocardiology. J Am Coll Cardiol 1994; 23(7):1592-7.
21. de Jongste MJ, Haaksma J, Hautvast RW et al. Effects of spinal cord stimulation on myocardial ischaemia during daily life in patients with severe coronary artery disease. A prospective ambulatory electrocardiographic study. Br Heart J 1994; 71(5):413-8.
22. Eddicks S, Maier-Hauff K, Schenk M et al. Thoracic spinal cord stimulation improves functional status and relieves symptoms in patients with refractory angina pectoris: the first placebo-controlled randomised trial. Heart 2007; 93(5):585-90.
23. Hautvast RW, DeJongste MJ, Staal MJ et al. Spinal cord stimulation in chronic intractable angina pectoris: a randomized, controlled efficacy study. Am Heart J 1998; 136(6):943-4.
24. Bondesson S, Pettersson T, Erdling A et al. Comparison of patients undergoing enhanced external counterpulsation and spinal cord stimulation for refractory angina pectoris. Coron Artery Dis 2008; 19(8):627-34.
25. Fox K, Garcia MA, Ardissino D et al. Guidelines on the management of stable angina pectoris: executive summary. The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology. Eur Heart J 2006; 27(11):1341-81.

Electrical Nerve Stimulation, Spinal
Spinal Cord Stimulation
Stimulation, Electrical, Spinal Cord