OHTAC Recommendation Spinal Cord Stimulation for the Management of Neuropathic Pain March 2, 2005 1
The Ontario Health Technology Advisory Committee (OHTAC) met on March 2, 2005 and reviewed the use of spinal cord stimulation for the management of neuropathic pain, following an application to OHTAC by the Toronto University Health Network (UNH). Based on a health technology policy analysis of spinal cord stimulation completed by the Medical Advisory Secretariat (MAS), OHTAC offers the following recommendations to the Ministry of Health and Long-Term Care (MOLTC) for its consideration. These recommendations comply with the OHTAC terms of reference. Neuropathic pain is described as burning, shooting or lancing pain caused by damage or dysfunction to the nervous system (Mersky, 1994). It is pain that is difficult to manage with other treatment modalities, becoming a chronic pain condition if symptoms persist beyond 6 months or exceed the expected time for tissue healing (The Canadian Pain Society, 1997). Chronic pain is an emotional, social and economic burden for those experiencing it. Depression, reduction in quality of life, absenteeism from work and a lower household income correlate positively with chronic pain (Meana, 2004; Moulin, 2002; Currie, 2004). The prevalence of depression among Canadians with chronic pain is twice that compared with those without chronic pain (Meana, 2004). 2
On average there are 9.3 working days missed by Canadians due to chronic pain and 16 days for those with severe pain (Moulin, 2002). Furthermore, there is a reported significant reduction in the income of people with chronic pain compared with those without chronic pain (Moulin, 2002). The estimated prevalence of neuropathic pain is 1.5% of the US population (Bennett, 1998) and up to 10% of all chronic pain is neuropathic pain (personal communication with Clinical Expert). Current standard treatments for neuropathic pain fall into three categories: pharmacological, non-pharmacological and surgical. However, approximately 10% of people will develop intractable pain defined as failure to obtain pain relief from standard treatments despite reasonable efforts.. This cohort is the target population for spinal cord stimulation. Many different medical conditions elicit neuropathic pain. However, three medical conditions including leg and back pain after back surgery (failed back surgery syndrome), limb pain after injury (complex regional pain syndrome type I) and pain after herpes zoster infection (post herpetic neuralgia) are the most common neuropathic pain conditions treated with spinal cord stimulation. Developed in 1960, spinal cord stimulation is a form of neuromodualtion, a process that alters the transmission of nerve impulses to the brain. The 3
most common indication for its use is to manage chronic intractable neuropathic pain. The spinal cord stimulator device consists of a battery, an extension cable and a thin wire with electrodes on it called a lead. The battery is implanted under the skin in the abdomen. The extension cable runs underneath the skin and connects the battery to the lead, which is inserted into the epidural space and positioned on the posterior aspect of the spinal cord. The battery generates low voltage electrical pulses, which the electrodes conduct to the spinal cord. This action blocks the transmission of pain to the brain and initiates a paresthesia or tingling feeling over the painful body part, which masks the pain. Four spinal cord stimulator devices are licensed and approved by Health Canada for the management of chronic intractable pain. A neuropsychologist assesses potential spinal cord stimulation candidates for cognitive functioning and psychological comorbidities. If the assessment is favorable candidates then undergo a test stimulation period. During test stimulation, the physician inserts a lead into the epidural space and connects it to an external battery. The patient lives with the device for up to 1 week during which time he/she monitors their level of pain. People experiencing at least a 50% decrease in pain are eligible for permanent implantation of the spinal cord stimulator device. 4
After permanent implantation of the device, the patient requires on-going monitoring by a neurosurgeon or pain specialist. Up to 6 clinic visits may be required in the first year after implantation to monitor the patient and refine the stimulator parameter settings. Technical failures and procedural complications can occur. Lead migration (movement of the lead off its target spot in the epidural space) is the most common technical failure and occurs at a rate of 13.2% (Cameron, 2004). Local wound infection occurs at a rate of 3.4% most often at the battery implantation site. (Cameron, 2004). Six health technology systematic reviews have been completed since 2000. All concluded that spinal cords stimulation is an effective pain therapy. However, there is variation among these reviews regarding the quality of evidence. The Medical Advisory Secretariat evaluated the current literature to determine the effectiveness of spinal cord stimulation to manage chronic intractable neuropathic pain. Results indicated that spinal cord stimulation significantly reduced the level of pain in people with chronic neuropathic pain conditions. Likewise, there was supportive evidence for improvement in functional status and quality of life in people treated with spinal cord stimulation. 5
An estimated 5600 people per year will develop neuropathic pain from failed back surgery syndrome, complex regional pain syndrome type I and post herpetic neuralgia. Approximately 10 per cent will develop intractable pain. An estimated 70% will proceed to test stimulation after psychological testing of which on average 84% or 330 people/year will be eligible for permanent implantation. Currently Ontario does 30-50 spinal cord stimulation procedures annually. While eight hospitals in Ontario have implanted spinal cord stimulators, one centre is currently the most active, implanting approximately 30 people/year (data from London Health Sciences Centre medical records department). An Eastern Ontario hospital stopped implanting SCS approximately 1.5 years ago reportedly due to lack of infrastructure support and funding for the program. Likewise, a major Toronto SCS referral centre closed as of January 2005, for similar reasons. Five other centres do a minimum number of implants of SCS. A meta-analysis of 14 cost-effectiveness studies of SCS confirmed longterm cost-savings associated with this pain therapy (Taylor, 2004). A Canadian economic analysis of SCS compared with conventional pain therapy reported cost-savings of approximately $11,000 over a five-year post-operative period with the breakeven point at 2.5 years (Kumar, 2002). 6
The Medical Advisory Secretariat determined the Ontario specific costs of spinal cord stimulation. The total cost, including hospital costs, professional costs and device costs, is estimated at $20,000 per procedure. As a result of its review, OHTAC recommends: Increased access to this technology for the management of chronic intractable neuropathic pain within the context of a multidisciplinary comprehensive pain management program. 7