spinal cord stimulation for the treatment of chronic pain john talley parrot, md

Spinal Cord Stimulation for theTreatment of Chronic Pain

John Talley Parrot, MD

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

Disclosure Slide

Just So I Didn’t Forget My Questions Doctor Parrott

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.)

Chronic Pain

725k lumbar fusions/discectomies 2000(Agency for Healthcare Research and Quality. Healthcare Cost & Utilization Project (HCUP). Accessed May 10, 2007, athttp://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. )

Chronic Pain

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.

“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)

Epidemiology

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?

Diagnosis

First Tier

Second-Tier

Third Tier

Physical TherapyNSAIDSAnalgesics

NeurostimulationSurgical Intervention

Diagnostic blocksTherapuetic proc.s

ImagingEMG/NCS

Therapeutic Algorithm

Neuromodulation Devices

Allow the delivery of very small, precise doses of electricity

or drugs directly to targeted nerve sites.

Precise delivery of small doses of electricity directly to targeted nerve sites

Neuromodulation DevicesElectrical Stimulators

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 NEURONAaAb FIBERS

INHIBITORYINTERNEURON

C FIBER



Gate Control Theory

Pain

Sensory

When sensory impulses are greater than pain impulses “Gate” in the spinal cord closes preventing the pain signal

from reaching the brain

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



Pain

Sensory

Gate

SCS

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

27

Factors Influencing Therapy Success

Clinical Indications Pain etiology Pain distribution Patient factors

SCS Device Sufficient coverage Targeting of electrical field Sustainability of therapy

© 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 TrialsThe 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 Low to moderate

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 StudiesReduction in painAuthor 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 3 years 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 StudiesReduction in medicationAuthor No. Patients Follow-Up Results

North 19 3 years 50% reduced their med use

Van Buyten 123 3 years >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



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 StudiesImprovement in daily activitiesAuthor 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.


SCS StudiesReturn to workAuthor 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 3 years 35% returned to work


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.

Questions?

spinal cord stimulation for the treatment of chronic pain john talley parrot, md

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