Evidence Based Medicine for Evidence Based Medicine for SCSSCS

Steven M. Falowski MDSteven M. Falowski MD

St. Lukes Health NetworkSt. Lukes Health Network

Bethlehem, PABethlehem, PA

Advantages of SCS TherapyAdvantages of SCS Therapy

SafeSafe

TestableTestable

Non-destructiveNon-destructive

Mostly reversibleMostly reversible

Long-term cost is lowLong-term cost is low

Less RiskyLess Risky

Disadvantages of SCS TherapyDisadvantages of SCS Therapy

Limited to specific indications and diseasesLimited to specific indications and diseasesEquipment failureEquipment failureFollow-up lifelong?Follow-up lifelong?Short-term cost is highShort-term cost is highInability to get MRIInability to get MRI

IndicationsIndications

Most CommonMost Common– Post-laminectomy syndrome Post-laminectomy syndrome – Complex regional pain syndrome (CRPS) Complex regional pain syndrome (CRPS) – Ischemic limb pain Ischemic limb pain – AnginaAngina

Other Other – visceral/abdominal pain visceral/abdominal pain – cervical neuritis paincervical neuritis pain– spinal cord injury painspinal cord injury pain– post-herpetic neuralgiapost-herpetic neuralgia– neurogenic thoracic outlet syndrome neurogenic thoracic outlet syndrome

Mechanism of ActionMechanism of Action

Foreman et al. 1976Foreman et al. 1976 Primate Studies Primate Studies

Linderoth et al. 1992Linderoth et al. 1992 Rat Studies Rat Studies

At the chemical level, animal studies At the chemical level, animal studies suggest that the SCS triggers the release suggest that the SCS triggers the release of serotonin, substance P, and GABA of serotonin, substance P, and GABA within the dorsal hornwithin the dorsal horn

?Descending Inhibition?Descending Inhibition

Mechanism Of ActionMechanism Of Action

Barolat 1993Barolat 1993: Mapping of sensory : Mapping of sensory responsesresponses

Barolat 1998Barolat 1998: Anatomical and electrical : Anatomical and electrical properties of the intraspinal structures and properties of the intraspinal structures and clinical correlations clinical correlations

Mechanism of Action-ElectrodesMechanism of Action-Electrodes

Transverse tripolar stimulation (4 pts)Transverse tripolar stimulation (4 pts)Central cathode and two lateral anodesCentral cathode and two lateral anodesAnodes increase the discomfort threshold Anodes increase the discomfort threshold over the roots compared to the over the roots compared to the paresthesia threshold (thus increasing the paresthesia threshold (thus increasing the therapeutic range)therapeutic range)Lateral/medial steering advantage by Lateral/medial steering advantage by setting different voltages of the flanking setting different voltages of the flanking anodesanodesCloser spacing = More effective fiber Closer spacing = More effective fiber activationactivation

Post- Laminectomy SyndromePost- Laminectomy Syndrome

Etiology:Etiology:– Pain in Center Lower Pain in Center Lower

Lumbar AreaLumbar Area– Pain in ButtocksPain in Buttocks– Radicular PainRadicular Pain

Also included:Also included:– ArachnoiditisArachnoiditis– Epidural FibrosisEpidural Fibrosis– RadiculitisRadiculitis– MicroinstabilityMicroinstability– Recurrents Disc Recurrents Disc

HerniationsHerniations– InfectionsInfections

Post- Laminectomy SyndromePost- Laminectomy Syndrome

North et al-1991:North et al-1991: SCS is superior to SCS is superior to repeat surgeryrepeat surgery– 50 patients50 patients– Average 3 surgeries Average 3 surgeries

for FBSS prior to SCSfor FBSS prior to SCS– 53% of patients had 53% of patients had

pain relief at 2.2 yearspain relief at 2.2 years– Patient SatisfactionPatient Satisfaction

North et al-1995:North et al-1995: Better outcomes with Better outcomes with SCSSCS– Prospective RCTProspective RCT– Repeat back surgery Repeat back surgery

vs SCSvs SCS– Allowed CrossoverAllowed Crossover

– 51 studies51 studies– Total of 3,700 patientsTotal of 3,700 patients– SCS had a positive, symptomatic, long-term SCS had a positive, symptomatic, long-term

effect in cases of:effect in cases of: refractory angina pain, severe ischemic limb pain refractory angina pain, severe ischemic limb pain secondary to peripheral vascular disease, secondary to peripheral vascular disease, peripheral neuropathic pain, and chronic low-back peripheral neuropathic pain, and chronic low-back painpain

ResultsResults

CLINICAL RESULTS: CLBPCLINICAL RESULTS: CLBP North et al North et al Neurosurgery 2005;56:98-Neurosurgery 2005;56:98-

107107F

BS

S p

atie

nts

(%

)

More than 50%pain relief

Increase inopiate analgesia

SCS

Reoperation

0

20

40

60

80

100

p = 0.0149

p = 0.0005RCTRCT

Clinical efficacy:Clinical efficacy:– RCT:RCT:

47% SCS patients had 47% SCS patients had 50% pain relief and expressed 50% pain relief and expressed satisfaction with treatment, compared with only 12% satisfaction with treatment, compared with only 12% reoperation patientsreoperation patients

87% of SCS patients had stable or reduced opioid use; 87% of SCS patients had stable or reduced opioid use; 42% reoperation patients required an increase42% reoperation patients required an increase

Cost effectiveness:Cost effectiveness:– Considerable cost savings after 2.5 yearsConsiderable cost savings after 2.5 years

SCS in CLBPSCS in CLBP SCS in CLBPSCS in CLBP

Worsening

Improved

No change

1. Ohnmeiss DD, Rashbaum RF. The Spine Journal 2001;1:258-363 [dual leads were required for these patients]

60%34%

6%

78% of patients would recommend SCS to someone with a similar problem, 78% of patients would recommend SCS to someone with a similar problem,

75% of patients would have the procedure performed again if they had 75% of patients would have the procedure performed again if they had known their outcome before implantationknown their outcome before implantation

Quality of life with Quality of life with neurostimulation in CLBP neurostimulation in CLBP

Quality of life with Quality of life with neurostimulation in CLBP neurostimulation in CLBP

Spinal cord stimulation versus re-operation in patients with failed back Spinal cord stimulation versus re-operation in patients with failed back surgery syndrome: an international multicenter randomized controlled surgery syndrome: an international multicenter randomized controlled

trial (EVIDENCE study).trial (EVIDENCE study).North RB, Kumar K, Wallace MS, Henderson JM, Shipley J, Hernandez J, Mekel-Bobrov North RB, Kumar K, Wallace MS, Henderson JM, Shipley J, Hernandez J, Mekel-Bobrov

N, Jaax KN.N, Jaax KN.Neuromodulation.Neuromodulation. 2011 Jul-Aug 2011 Jul-Aug

Assess the effectiveness and cost-effectiveness of spinal Assess the effectiveness and cost-effectiveness of spinal cord stimulation (SCS) with rechargeable pulse cord stimulation (SCS) with rechargeable pulse generator versus re-operation generator versus re-operation Study subjects have neuropathic radicular leg pain Study subjects have neuropathic radicular leg pain exceeding or equaling any low back pain and meet exceeding or equaling any low back pain and meet specified entry criteria. specified entry criteria. Co-primary endpoints are proportion of subjects Co-primary endpoints are proportion of subjects reporting ≥ 50% leg pain relief without crossover after reporting ≥ 50% leg pain relief without crossover after SCS screening trial or re-operation. SCS screening trial or re-operation. Secondary endpoints include cost-effectiveness; relief of Secondary endpoints include cost-effectiveness; relief of leg, back, and overall pain; change in disability and leg, back, and overall pain; change in disability and quality of life; and rate of crossover. quality of life; and rate of crossover.

Complex Regional Pain Complex Regional Pain SyndromeSyndrome

CRPS-Early WorkCRPS-Early Work

Barolat et at-1989Barolat et at-1989– Pain reduction in 10 of 13 patientsPain reduction in 10 of 13 patients– Short follow upShort follow up

Kumar et al- 1997Kumar et al- 1997– 41 month follow up of 12 patients41 month follow up of 12 patients– All patients with pain reliefAll patients with pain relief

CRPSCRPS

Kemlar -1999:Kemlar -1999: 78% pain relief 78% pain relief – 23 patients23 patients

Kemlar- 2000:Kemlar- 2000: SCS vs Physical Therapy SCS vs Physical Therapy– 54 Patients randomized54 Patients randomized– 67% pain relief at 6 months67% pain relief at 6 months– Improved VAS scoresImproved VAS scores

Kemlar- 2006:Kemlar- 2006: Diminished effectiveness Diminished effectiveness over 5 year follow upover 5 year follow up

Long-term outcomes of spinal cord stimulation with paddle leads in the treatment Long-term outcomes of spinal cord stimulation with paddle leads in the treatment of complex regional pain syndrome and failed back surgery syndrome.of complex regional pain syndrome and failed back surgery syndrome.

Sears NC, Machado AG, Nagel SJ, Deogaonkar M, Stanton-Hicks M, Rezai AR, Sears NC, Machado AG, Nagel SJ, Deogaonkar M, Stanton-Hicks M, Rezai AR, Henderson JM.Henderson JM.

NeuromodulationNeuromodulation.. 2011 Jul-Aug 2011 Jul-Aug More than 50% of the patients with CRPS More than 50% of the patients with CRPS reported greater than 50% pain relief at a mean reported greater than 50% pain relief at a mean follow-up of 4.4 years. follow-up of 4.4 years. Approximately 30% of the FBSS patients Approximately 30% of the FBSS patients reported a 50% or greater improvement at a reported a 50% or greater improvement at a mean follow-up of 3.8 years. mean follow-up of 3.8 years. However, 77.8% of patients with CRPS and However, 77.8% of patients with CRPS and 70.6% of patients with FBSS indicated that they 70.6% of patients with FBSS indicated that they would undergo SCS surgery again for the same would undergo SCS surgery again for the same outcome.outcome.

CRPS-LimitationsCRPS-Limitations

Difficult to cover affected area with Difficult to cover affected area with stimulationstimulation

Long- term efficacy is yet to be determinedLong- term efficacy is yet to be determined

Improvement in pain scores, but not Improvement in pain scores, but not necessarily improvement in functional necessarily improvement in functional impairmentimpairment

Awake vs. Asleep Placement of Spinal CordStimulators: A Cohort Analysis of Complications

Associated With PlacementSteven M. Falowski, MD, Amanda Celii, MD, Anthony K. Sestokas, PhD,Daniel M. Schwartz, PhD, Craig Matsumoto, MPAS, Ashwini Sharan, MD

Neuromodulation. 2011 Mar-Apr;14(2):130-4; discussion 134-5

A retrospective review of 167 new A retrospective review of 167 new internalization operations internalization operations

Electrode implantation performed either Electrode implantation performed either under monitored (local anesthetic and under monitored (local anesthetic and intravenous sedation) or under general intravenous sedation) or under general anesthesiaanesthesia

Awake versus non-Awake Surgery for Placement of Spinal Cord Awake versus non-Awake Surgery for Placement of Spinal Cord StimulatorsStimulators

Device failure for patients implanted using Device failure for patients implanted using neurophysiologically-guided placement neurophysiologically-guided placement under general anesthesia was one-half under general anesthesia was one-half that for patients implanted awake (14.94% that for patients implanted awake (14.94% vs 29.7%). vs 29.7%).

No difference in repositioning or infection No difference in repositioning or infection raterate

Awake versus non-Awake Surgery for Placement of Spinal Cord StimulatorsAwake versus non-Awake Surgery for Placement of Spinal Cord Stimulators

Important Points:Important Points: – Radiographical position and motor stimulation Radiographical position and motor stimulation

responses to assure proper electrode positioning responses to assure proper electrode positioning under general anesthesiaunder general anesthesia

– Performed after a percutaneous trialPerformed after a percutaneous trial

Conclusion:Conclusion: – Non-awake surgery is associated with fewer Non-awake surgery is associated with fewer

failure rates and therefore fewer re-failure rates and therefore fewer re-operations, making it a viable alternativeoperations, making it a viable alternative

SCS-ConclusionsSCS-Conclusions

SCS Technology is improvingSCS Technology is improving– Equipment and stimulation parametersEquipment and stimulation parameters

Reliable and safe modalityReliable and safe modalityGoal of neurostimulation is to reduce pain Goal of neurostimulation is to reduce pain rather than to eliminate painrather than to eliminate pain– 50% improvement in pain relief50% improvement in pain relief– Reduce use of pain medicationsReduce use of pain medications

Increasing amount of usesIncreasing amount of uses– Importance of selection criteriaImportance of selection criteria