Spinal Cord Stimulation (SCS) Jeffrey S. Yablon M.D. Clinical - - PowerPoint PPT Presentation

Spinal Cord Stimulation (SCS)

Jeffrey S. Yablon M.D. Clinical Associate Professor of Neurological Surgery UCSF Medical Director Peggy Herman Center for the Neurosciences

June 1, 2013

Spinal Cord Stimulation

• There are no disclosures for this presentation

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Pain is a Significant Issue

• #1 Admitting diagnosis in US
• #1 Reason for missed work in US
• Chronic pain costs the US $100B / year in

direct medical costs, lost income and productivity

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Healthcare Costs

• Workers’ Compensation costs have increased

dramatically in recent years – From 1970-1990, premiums paid by employers in the US increased from $4.9 billion to $53.1 billion – The number of people in the workforce only increased from 59-95 million

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Healthcare Costs

• With Medical costs increasing at the rates

they are for the treatment of low back pain, it is imperative that patients get the care they need as early as possible

• Earlier intervention leads to better care and

better outcomes

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Chronic Pain

• Chronic pain is continuous pain that persists for

more than 3 months, and beyond the time of normal

• healing. It ranges from mild to severe and can last

weeks, months, or years to a lifetime. (http://www.niams.nih.gov)

• 20% of the population in developed countries is

afflicted with chronic pain

– 30-40% due to musculoskeletal and joint disorders – 30% neck and back pain – Headache and migraines < 10%

Pain Clinical Updates, Sep. 2004, IASP Pain Clinical Updates, Sep. 2004, IASP

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Neuropathic Pain

• 4M People in the US/year suffer from

Neuropathic pain (NP), caused by a primary lesion or dysfunction in the nervous system1

• Associated with diabetic peripheral

neuropathy, post herpetic neuralgia, human immunodeficiency virus-related disorders, and chronic radiculopathy.

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Neuropathic Pain

• Treatment often fails because1:
• Inadequate diagnosis and a lack of appreciation of

the mechanisms involved

• Insufficient management of comorbid conditions
• Incorrect understanding or selection of treatment
• ptions

1J Pain Symptom Manage. 2003 May;25

(5Suppl):S12-7

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Chronic Neuropathic Pain

Chronic, intractable, neuropathic pain is intense pain caused by injury to the nervous system that lasts several months or longer and is not relieved by medical and/or surgical care.

• It can result from an injury long since healed or from

an ongoing condition such as nerve damage, cancer,

• r chronic infections.
• Common causes include Failed Back Syndrome

(FBSS), Arachnoiditis, Complex Regional Pain Syndrome (CRPS), Radiculopathies, and Peripheral Neuropathy of Upper and Lower Extremity Nerves (Upper-Ulnar, Median, Radial. Lower–Tibial and Common Peroneal).

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Therapeutic Options

• Management of chronic pain includes a variety of
• techniques. Conservative, or noninvasive, treatments

are tried first; if these do not work, invasive, or advanced, techniques may be used.

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Selection Criteria for SCS

• Psychiatric and psychological assessment
• Evidence that psychiatric opinion is

effective in identifying poor risk candidates. Nielsen et al. Surg Neurol, 1975

• In Belgium, where reimbursement for SCS is

conditional upon psych assessment, success rate was 3X higher in those approved by psychiatrist in a series of 100 patients, Kupers et al. 1994

• Quality of the pain is important.
• Continuous burning, sharp. Other

neuropathic pain descriptors.

• Not effective against nociceptive pain such

as cancer pain, arthritis, wound pain, etc.

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Mechanism of SCS

• Generates electric field in

epidural space

• Stimulates axons of

dorsal column (primarily) and dorsal root fibers in spinal column

• Produces a pleasant

paresthesia.

• Need maximal control
• ver stimulation of the

targeted nerves, while preventing stimulation of undesired neurons.

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Current Indications

“Indicated as an aid in the management of chronic intractable pain of the trunk and/or limbs, including unilateral or bilateral pain associated with the following: Failed Back Surgery Syndrome, intractable low back pain and leg pain.” Commonly treated syndromes (approved when lead is placed in the epidural space)

• CRPS 1 & 2
• Arachnoiditis
• Post Thoracotomy Pain
• Peripheral Neuropathy
• Post Herpetic Neuralgia
• Phantom Limb Pain
• Ilioinguinal Neuralgia

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Failed Back Surgery Syndrome

• $20B annually in direct health care costs1
• 5th most common reason for MD visit1
• Patient continues to experience chronic back and/or leg pain

despite surgery. The most common reason for FBSS is poor patient selection (psychological, social, behavioral issues)

• Common Psychosocial disorders in FBSS
• Depression, Anxiety, Somatization, Personality disorders, and

secondary gain issues

• Strong evidence supports that low back pain is neuropathic
• Important to identify and treat other etiologies of FBSS that

are not neuropathic and not candidates for SCS

• Foraminal stenonsis, descogenic pain, recurrent disc herniation,

pseudoarthrosis, facetogenic pain, sacroiliac syndrome

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Chronic Postamputation Pain

• Two Possible Neuropathic syndromes
• Pain in the stump which is related to neuroma formation following

the sectioning of the sciatic nerve

• Pain is felt in the amputated extremity and is termed Phantom Pain
• SCS therapy is typically not the first line choice for pain

control Post Thoracotomy Syndrome

• Chronic chest wall pain syndromes that follow a

thoracotomy and sternotomy

• The pain is due to injury to at least one intercostal nerve

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Studies of Clinical Effectiveness

Early study Conclusions re: SCS:

• SCS was significantly more successful than reoperation in giving selected FBSS patients

at least 50% pain relief.*

• Lower morbidity than surgery and opportunity for therapeutic trial are important

advantages.*

• Computerized system optimized pain relief better, more than doubled battery life, and

reduced costs by about one-third.**

• Battery life is a major SCS cost driver. If it can be prolonged, lifetime savings can exceed

$300,000 for average patient.**

• SCS was less expensive and more effective than reoperation in selected failed back-

surgery syndrome patients, and should be the initial therapy of choice. SCS is most cost-effective when patients forego repeat operation. Should SCS fail, reoperation is unlikely to succeed.

• 6-month outcomes demonstrate significant improvements of SCS patients compared to

CMM group -Significantly more SCS patients (48% versus 9%) achieved the primary

• utcome of ≥ 50% pain relief (p<0.001).

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Studies of SCS Effectiveness

Study

• Kemler & Furnee 2002
• Kumar 2002
• Alo 2002

Outcome

• CRPS – Pain but not

functional status or depression improved compared with PT

• FBS – SCS group

improved 15% > non SCS group

• Significant improvement

in pain. 8/10 prior to surgery to 4.9/10 4 years post surgery.

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Summary

• Chronic pain is a pervasive, expensive problem for society,

government, employers, payers, and individuals.

• SCS has been proven effective for chronic neuropathic pain in

many studies over decades, including recent RCTs.

• Present generation devices have overcome the technical

problems and high failure rates common in early devices.

• Routine trial stimulation, better patient selection criteria, and

improved understanding of appropriate indications insure that SCS is only performed in those who have a high likelihood

• f benefit.
• Cost analyses have repeatedly shown that SCS saves

money when used appropriately.

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Trial Stimulation:

Temporary Percutaneous Lead

• Preferred test

stimulation for surgical paddle leads

• Lead implanted

and secured to skin

• Allows for test

stimulation

• f several days

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SCS System Types

• Conventional SCS Technologies
• Radio Frequency

– Requires patient to wear external equipment to power the implant

• Fully implantable, Primary Cell battery

– Short life span and repeat replacement surgeries

• Advanced SCS Technology
• Fully implantable, rechargeable power

– Long lasting – Significantly smaller implant – Increased stimulation parameters and therapy options

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Permanent Trial

• More invasive trial
• ption
• Why use permanent

trial technique? – challenging lead placement – physician preference

• Advantages vs.

disadvantages

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Permanent Implant

• Begin same method as

trial

• Remove extension

from permanent trial

• Remove splitter

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• Using fluoro of trial lead as

reference for place permanent leads

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Surgical Lead Implantation

Surgical Lead Implantation

• Surgical lead choice
• Procedure

– Laminotomy – Surgical lead placement

• Advantages vs. disadvantages

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Success of Spinal Cord Stimulation

• Assure lead stability
• Review instructions with patient’s family
• Ensure patient’s full understanding of system operation
• Successful stimulation demands topographic coverage of the

electrical field of paresthesia over the area of the pain

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Common Surgical SCS Complications & How to Avoid Them

#1 SCS Complication

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Lead migration is cited as the #1 complication.

Lead Migration

Prevention

• Insert long length of lead in

epidural space

• Anchor securely to fascia /

supraspinous ligament

• Hard copies of intra-op fluoro
• Limit physical activity for at

least 2 weeks – No lifting objects > 5 lbs – No twisting, bending, or climbing – Do not raise arms above head

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Lead Breakage

• Presentation
• Loss of simulation-induced paresthesia
• May occur at any time
• Management
• Plain spine radiographs to assess continuity
• f wires (usually normal)
• Check impedances
• If necessary, replace electrode

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SCS Infections

– Main organisms S aureus, and S epidermidis, and 3 % Pseudomonas – Sites: pocket 54%, tract 17%, insertion 8% – SCS systems removed in 94 % of cases – 56 % of infections occurred in first 2 months – No data on when to re-implant after eradication of the infection

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Infection

• The risk of pocket and catheter infections range from 2 - 5%

and appears to be similar with spinal cord stimulators and intrathecal drug delivery devices.

• The risk of deep infections including epidural abscess and

meningitis ranges from 0 – 0.5%.

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Guidelines for Infection Prevention

– All remote infections are resolved – Avoid removing hair – Preoperative IV antibiotics – Avoid vancomycin prophylaxis – Optimal blood glucose control – Cease Tobacco use

– Antiseptic bath prior to surgery – 2-5 min scrub prep – Mark device pocket site – Sterile Technique – Occlusive dressings

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Infection Prevention: Antibiotic Prophylaxis

• RECOMMENDATION
• Category IA
• cefazolin 1-2 g iv 30 minutes prior to incision
• clindamycin 600 mg iv 30 minutes prior to incision

(in patients with ß-lactam allergy]

• vancomycin 1 g iv over 60 minutes prior to

incision

• (in MRSA carriers)

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Hematoma

• Management
• Consider benefits/risks of reopening wound vs.

allowing to resolve on its own

• Baseline lab & imaging tests for clinically significant

hematomas

• Potential surgical intervention
• Prevention
• Meticulous hemostasis
• Role of anticooagulant therapy, OTC agents, and

supplements

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Other Surgical Complications

• Seroma
• Skin erosion
• Wound dehiscence
• Rare:

– Epidural hemorrhage – Neurological deficit – Severe abdominal pain – Paralysis

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Summary

• Most complications are not life-threatening and can be

resolved

• Technology has improved and equipment failures are

now less common

• Meticulous technique can help to minimize common

complications

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