Spinal Cord Stimulation for the Treatment of Chronic Pain John Talley Parrot, MD

I am a faculty consultant for Medtronics and Synthes / AO Spine Disclosure Slide I have no financial relationships with any commercial interest related to the content of this activity I am a faculty consultant for Medtronics and Synthes / AO Spine So, effective treatment of chronic LBP is critical and hinges on an accurate diagnosis. For no treatment option will be effective if it is targeting the wrong structure.

Just So I Didn’t Forget My Questions Doctor Parrott

Chronic Pain Lifetime prevalence > 70% (Damkot DK, Pope MH, Lord J, Frymoyer JW.The relationship between work history, work environment and low back pain in men. Spine 9:395, 1984.) US 1 year prevalence rate—5-20% (Cunningham LS, Kelsey JL: Epidemiology of musculoskeletal impairments and associated disability. Am J Public Health. 74:574, 19848.Deyo RA, Tsui-Wu Y-J: Descriptive Epidemiology of low back pain and its related medical care in the United States. Spine 12; 264-268, 1987.) Annual direct medical costs $25 billion (Frymoyer JW, Cats-Baril WL. An overview of incidences and costs of low back pain. Orthop Clin North America 1991; 22:263-71.) Most common cause of disability < 45 y/o 2.4 million disabled Return To Work = 0 after 2 yr absence d/t LBP (Bigos SJ, Bettie MC: The impact of spinal disorders in industry. The Adult Spine. New York, Raven Press, 1991.) So, effective treatment of chronic LBP is critical and hinges on an accurate diagnosis. For no treatment option will be effective if it is targeting the wrong structure.

Chronic Pain 725k lumbar fusions/discectomies 2000 (Agency for Healthcare Research and Quality. Healthcare Cost & Utilization Project (HCUP). Accessed May 10, 2007, at http://www.ahrq.gov/data/hcup/) 30k-40k lumbar laminectomy patients/yr obtain no relief or recurrence of symptoms (Keane GP. Failed low back surgery syndrome. In: Cole AJ, ed. The low back pain handbook. Phila- delphia: Mosby; 1997:269–81. ) So, effective treatment of chronic LBP is critical and hinges on an accurate diagnosis. For no treatment option will be effective if it is targeting the wrong structure.

Long-Term Pain Affects Most of Your Patients 3 out of 4 Americans have experienced chronic or recurring pain or have a family member who has experienced such pain Almost 62% of pain sufferers have had their pain for a year or more A majority of adults (57%) have experienced chronic or recurring pain, including 54% of adults aged 18–34 Reference: Americans Talk about Pain, conducted by Peter D. Hart Research Associates for Research!America, August 2003.

Millions of Americans Suffer With Pain… 50 million Americans are partially or totally disabled by chronic pain 9 out of 10 Americans (aged 18 and older) suffer with pain at least once a month 77% of pain patients strongly agree that new options are needed to treat their pain 50% of Americans (aged 65 and older) suffer daily pain Reference: Pain in America: A Research Report, conducted by the Gallup Organization for Merck, June 1999.

Epidemiology “Failed Back Surgery Syndrome” Heterogenous group of disorders Specific diagnosis neither implicit or explicit Multiple possible explanations Persistent/recurrent/new LBP or lower limb pain Multiple etiologies (Slipman - Pain Med 2002, Schoferman -Pain Med 2002, Bernard - Spine 1993, Long J. - NS 1988) So, effective treatment of chronic LBP is critical and hinges on an accurate diagnosis. For no treatment option will be effective if it is targeting the wrong structure.

It’s imperative that the treating spine specialists clearly understand and recognize surgical vs nonsurgical etiologies for recurrent radicular pain after lumbosacral surgery. Proper treatment of the former after conservative measures fail must include surgical intervention in order to optimize treatment outcomes. Non-surgical etiologies containing stable surgical constructs represent conditions which may be sufficiently addressed with non-surgical treatment options including SCS. Slipman CW. Etiologies of Failed Back Surgery Syndrome, Pain Medicine 2002;3(3):200-214

Nociceptive Pain Somatic pain arises from: Bone and joint Muscle Skin Connective tissue Aching or throbbing Localized Visceral pain arises from: Visceral organs such as GI tract and pancreas Tumor involvement Obstructive

Neuropathic Pain Abnormal processing of sensory input by the peripheral or central nervous system Centrally generated pain Peripherally generated pain Dorsal Root Ganglion (DRG) Nerve Root

Neuropathic Radicular Pain http://www.netterimages.com/image/list.htm?page=2&s=spinal%20cord; image 1317)

Mixed Pain Many patients have a combination of both nociceptive and neuropathic pain Disease or trauma has damaged both nerve cells and other tissues

History of Neurostimulation One of the earliest uses of electricity in medicine was for pain relief. Around 15 A.D., Scribonius reported that a torpedo fish could be used to apply an electrical charge to patients to relieve pain. Reference: Gildenberg PL. History of electrical neuromodulation for chronic pain. Pain Medicine. 2006;7(S1):S7-S13

What is Spinal Cord Stimulation?

Therapeutic Algorithm Third Tier Second-Tier Neurostimulation Surgical Intervention First Tier Diagnostic blocks Therapuetic proc.s Diagnosis Physical Therapy NSAIDS Analgesics Imaging EMG/NCS

Neuromodulation Devices Allow the delivery of very small, precise doses of electricity or drugs directly to targeted nerve sites.

Neuromodulation Devices Electrical Stimulators Precise delivery of small doses of electricity directly to targeted nerve sites

Spinal Cord Stimulation (SCS) Implanted medical device that delivers electrical pulses to nerves in the dorsal aspect of the spinal cord that can interfere with the transmission of pain signals to the brain and replace them with a more pleasant sensation called paresthesia.

CNS Pain Management (Theory) Gate Control Theory Melzack and Wall, 1968 C FIBER PROJECTION NEURON AaAb FIBERS INHIBITORY INTERNEURON

INHIBITORY INTERNEURON Gate Control Theory When sensory impulses are greater than pain impulses “Gate” in the spinal cord closes preventing the pain signal from reaching the brain C FIBER PROJECTION NEURON AaAb FIBERS INHIBITORY INTERNEURON Sensory Pain

INHIBITORY INTERNEURON Gate Theory and SCS SCS system implanted near dorsal column stimulates the pain-inhibiting nerve fibers masking painful sensation with a tingling sensation (paresthesia) C FIBER PROJECTION NEURON AaAb FIBERS INHIBITORY INTERNEURON Sensory SCS Gate Pain

Tenets of SCS Comprehensive trial Customizable system components Optimized efficiency in programs and design Team approach to patient care Anesthesia Pain Physician Orthopedic Spine / Neurosurgeon SCS Medical Device Clinical Representatives

Advantages of SCS Therapy Safe Testable ** Non-destructive Mostly reversible Long-term cost is low

Disadvantages of SCS Therapy Refractory on some patients Potential equipment failure Short-term costs can be high, but are reimburseable via Medicare, workers compensation, and the private payer community Long term follow-up required via anesthesia pain management, and / or SCS medical device clinical representation Steep learning curve for procedure

Overall Goals of SCS Therapy Position electrode in area of specific neural target Generate electrical field at target nerve to create paresthesia that overlaps painful area(s) Program stimulation parameters for maximum effectiveness, patient comfort, and energy efficiency Reduce medication, restore function and improve quality of life Return patient to work

Factors Influencing Therapy Success Clinical Indications Pain etiology Pain distribution Patient factors SCS Device Sufficient coverage Targeting of electrical field Sustainability of therapy 27 © 2010 St. Jude Medical, Inc. All rights reserved.

Clinical Factors Indication Responsive to SCS Disease Etiology Disease likely to progress should have device with “extra capacity” Pain Distribution Multi site and broad pain patterns often require more leads and electrodes Patient Factors Anatomy Physiology Selection

Device Factors Stimulation Coverage Paresthesia is delivered to entire painful segment(s) Precision of Stimulation Not delivered to extraneous sites but masks the pain with a tolerable sensation Sustainability of Therapy Sustained over the painful anatomical segment

How Are Clinical Factors Evaluated? Patient Selection Process Correctly diagnosed Failed lower level therapies Successfully passed psyche evaluation Patient is motivated Patient is educated

How Are Device Factors Evaluated? During a Temporary SCS Trial Leads are implanted External power source is used to evaluate Pain relief Paresthesia coverage Power requirements Programming needs System requirements (Rechargeable Or Conventional)

SCS Phases Trial Permanent implant

Trials One advantage of SCS over the other pain management or surgical therapies is that it can be tested on patients before an SCS device is permanently implanted. The trial gives the implanting physician important information for determining which of the three SCS systems is appropriate for a specific patient.

Trials A spinal cord stimulation trial involves A short outpatient procedure during which the implanting physician places one or more leads in the space over the spinal cord. The patient is awake during the procedure so that he or she can provide feedback to the physician regarding exact placement. The lead connects to a device that can be worn on a belt. The device may contain a variety of programs.

Trial System Trial Lead Trial Cable Trial Generator/ Programmer

Length of Trials Trial length determined by daily verbal patient verbal Anesthesia pain physician staff – daily telephone calls SCS clinical representatives – daily telephone calls and office visit for adjustment intra-trial if needed Short-term trials 2 to 5 days Long-term trials 5 to 7 days

The Patient’s Role in Trials The patient should: Have a working knowledge of the SCS trial device Understand movement restrictions Reduce bending at the waist Reduce lifting over the head Understand the sensations to be expected Be able to document his or her responses, pain level, and functional changes Be reasonably active

Patient/Device Criteria Conventional IPG Rechargeable IPG Power requirements Low to moderate Moderate to high Frequency requirements Low Pain Stable Likely to progress Coverage needs (contacts/leads) 8 contacts on 1 or 2 leads 8 or 16 contacts on 1-4 leads Compliance (motivation and ability) Requires very little interaction High—due to recharging protocol Competence (physical or mental) Appropriate for all levels Higher level required Skin sensitivity Patients with high sensitivity Patients with moderate to low sensitivity Implant size Moderate to large sizes Small to moderate size Implant longevity 2-7 years 5-10 years Patient interface Easier to use Requires management

Single Or Dual Trial Leads

Paddle Lead Arrays Tripolar Paddle Array Penta Five Column Array

SCS Studies Reduction in pain Author No. Patients Follow-Up Results Kumar 410 8 years 74% had ≥ 50% relief North 19 3 years 47% had ≥ 50% relief Barolat 41 1 year 50%-65% had good/excel. relief Van Buyten 123 68% had good/excel. relief Cameron 747 up to 59 mos. 62% had ≥ 50% relief or significant reduction in pain scores Kumar K, Hunter G Demeria D. Spinal Cord Stimulation in Treatment of Chronic Benign Pain: Challenges in Treatment Planning and Present status, a 22-Year Experience. Neurosurgery. 2006;58:481-496. North RB,Kidd DH, Farrokhi F,Piantadosi SA. Spinal Cord Stimulation versus Repeated Lumbosacral Spine Surgery for Chronic Pain: a Randomized Controlled Trial in Patients with Failed Back Surgery Syndrome. Pain.2007;132:179-188. Barolat G, Oakley JC, Law JD, North RB, Ketick B, Sharan A. Epidural Spinal Cord Stimulation with a Multiple Electrode Paddle Lead is Effective in Treating Intractable Low Back Pain. Neuromodulation. 2001;4:59-66. Van Buyten JP,Van Zundert J,Vueghs P, Vanduffel L. Efficacy of Spinal Cord Stimulation : 10 Years of Experience in a Pain Centre in Belgium. Eur J Pain. 2001;5:299-307. Cameron T. Safety and Efficacy of Spinal Cord Stimulation for the Treatment of Chronic Pain: A 20-Year Literature Review. J Neurosurg Spine. 2004;100(3):254-267.

SCS Studies Reduction in medication Author No. Patients Follow-Up Results North 19 3 years 50% reduced their med use Van Buyten 123 >50%reduction in med use Cameron 766 up to 84 mos. 45% reduced their med use Taylor 681 n/a 53% no longer needed Analgesics North RB,Kidd DH, Farrokhi F,Piantadosi SA. Spinal Cord Stimulation versus Repeated Lumbosacral Spine Surgery for Chronic Pain: a Randomized Controlled Trial in Patients with Failed Back Surgery Syndrome. Pain.2007;132:179-188. Van Buyten JP,Van Zundert J,Vueghs P, Vanduffel L. Efficacy of Spinal Cord Stimulation : 10 Years of Experience in a Pain Centre in Belgium. Eur J Pain. 2001;5:299-307. Cameron T. Safety and Efficacy of Spinal Cord Stimulation for the Treatment of Chronic Pain: A 20-Year Literature Review. J Neurosurg Spine. 2004;100(3):254-267. Taylor RS, Van Buyten JP, Buchser E. Spinal Cord Stimulation for Chronic Back and Leg Pain and Failed Back Surgery Syndrome: A Systematic Review and Analysis of Prognostic Factors. Spine. 2005;30:152-160.

SCS Studies Improvement in daily activities Author No. Patients Follow-Up Results Barolat 41 1 year As a group, significant improvements in function and mobility North 19 3 years As a group, improvements in a range of activities Barolat G, Oakley JC, Law JD, North RB, Ketick B, Sharan A. Epidural Spinal Cord Stimulation with a Multiple Electrode Paddle Lead is Effective in Treating Intractable Low Back Pain. Neuromodulation. 2001;4:59-66. North RB,Kidd DH, Farrokhi F,Piantadosi SA. Spinal Cord Stimulation versus Repeated Lumbosacral Spine Surgery for Chronic Pain: a Randomized Controlled Trial in Patients with Failed Back Surgery Syndrome. Pain.2007;132:179-188.

SCS Studies Return to work Author No. Patients Follow-Up Results Van Buyten 123 3 years 31% returned to work Taylor 1,133 n/a 40% returned to work Dario 23 35% returned to work Van Buyten JP,Van Zundert J,Vueghs P, Vanduffel L. Efficacy of Spinal Cord Stimulation : 10 Years of Experience in a Pain Centre in Belgium. Eur J Pain. 2001;5:299-307. Taylor RS, Van Buyten JP, Buchser E. Spinal Cord Stimulation for Chronic Back and Leg Pain and Failed Back Surgery Syndrome: A Systematic Review and Analysis of Prognostic Factors. Spine. 2005;30:152-160. Dario A, Fortini G, Bertollo D, Bacuzzi A, Grizzetti C, Cuffari S. Treatment of Failed Back Surgery Syndrome. Neuromodulation. 2001;4:105-110.

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