Interventional pain fellow Hudson Medical group 682018 Outline Spinal Cord Stimulator SCS Techniques Lumbar technique Cervical technique Evidence Traditional SCS High Frequency SCS HF10 ID: 725721
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Slide1
Spinal Cord Stimulation
Benjamin Bonte, MD
Interventional pain fellow
Hudson Medical group
6/8/2018Slide2
Outline
Spinal Cord Stimulator (SCS)
Techniques
Lumbar technique
Cervical technique
Evidence
Traditional SCS
High Frequency SCS (HF-10)
Burst stimulationSlide3
SCS mechanism
Gate control theory of pain
Aδ
fibers – myelinated, medium diameter, fast conduction (40mph)
C fibers – unmyelinated, small diameter, slower conduction (3mph)
Aβ fibers - transmission of touch, pressure, proprioceptionIf gate is overwhelmed with nonpainful stimuli, theory proposes this leads to failed transmission of pain signals from Aδ fibers and C fibers1967 – Norman Shealy implanted monopolar SCS lead into intrathecal space.Exact mechanism is unknown. Likely:Suppression of central excitability for neuropathic painVasodilation, inhibited sympathetic outflow for ischemic painSlide4
Indications for SCS
Failed Back Surgery Syndrome (FBSS)
Chronic radicular pain
Extremity neuropathic pain
CRPS
Axial pain preferably by using burst or HF SCSIschemic pain, Raynaud syndromeSlide5
Contraindications for SCS
Uncontrolled psychiatric disorders
Unable to stop anticoagulation
Systemic Infection/drug use
Cognitive concerns
Unclear pain generatorPlatelets <100kSlide6
SCS electrodes
Percutaneous leads
Flexible, cylindrical, polyurethane. Generally 8-16 contacts. Circumferential current flow
Paddle leads
Flat, wide, and rectangular
Insulation on one side/unidirectional toward cord with up to 32 lead contacts.Requires more invasive approach by spine surgeon.Increased risk of complications, factures, and infections.Considered with difficult anatomy, undesirable position stimulation or if Slide7
Power source
Primary cell implantable pulse generator (IPG)
Lifespan 3-4 years
Low maintenance
Rechargeable IPG
Lifespan 9 yearsSlide8
SC S trial procedure
Fluoroscopy guided under sterile conditions
Prophylactic antibiotics are advocated; a cephalosporin such as cefazolin.
If beta-lactam allergy, clindamycin is recommended.
If patient is MRSA positive, vancomycin is recommendedSlide9
SCS trial procedure
Introducer needle started 1-2 levels below entry point
Depends on habitus of patient
T12-L1 is typical placement; more limited movement of spine here prevents lead migration during trial
L2-3 is below conus, dura is more distensible at this levelSlide10
SCS trial procedure
single lead placement may suffice if adequate coverage of the painful area is achieved
Avoid ventral migration of leads
Anchor leads and educate patient regarding SCS trial, avoiding bending/twisting.Slide11
Cervical SCS
Access to cervical interlaminar space obtained between C7-T1 through T2-T3.
Tilt as caudally as possible to obtain trajectory view, and slightly oblique to the symptomatic side.
Varies based on anatomy, but generally 4mm of room at C7-T1.Slide12
Cervical SCS
Furman recommends advancing with frequent checks of lateral or contralateral oblique view until reaching the
spinolaminar
line, then using air or lead blank
“saline can potentially increase impedance”
Waldman “48 hour trial period” in contrast to lumbarSlide13
Suboptimal situations include
Dural puncture (0.5%)
Epidural vein trauma
Painful but self limiting
Epidural hematoma
Rare Neuro complications even rarer but potentially catastrophicInfection/hardware failurerareSlide14
SCS electrode target
Placement of the electrodes for a few important and frequently used targets includes the following:
C2: lower half of face
C2-C4: neck, shoulder, hand
Mid Cervical spine has high mobility thus position changes can lead to lead migration.
Cervical elad placement in general imvolves placement between T1-T4 and superior advancement.T5-T6: abdomenCSF diameter is largest dorsally at T5 thus stimulation thresholds are higher and postural changes can affect outcome.T7-T9: backT10-T10: legT12-L1: footL1: pelvisLeadts directed at conus and cauda equina are more vulnerable to patient movement as there are free floating spinal nerves in this areas.Slide15
Programming Parameters
Amplitude
Intensity of each pulse, adjusting voltage or current.
Pulse width
Duration of pulse in microseconds. Usually 100-400microseconds.
RateHz – traditional (20-150) or HF (10k)Electrode selectionWhich ones are activeSlide16
Traditional SCS
Therapeutic sensation covers distribution of pain.
Frequencies 50-150hz.Slide17
Burst SCS
500hz spikes, pulse with of 1 millisecond,
constanc
current.
Thought to stimulate medial and lateral pain pathways
Medial – involved in attention paid to pain/behavioral aspects related to painLateral – somatosensory/localizing pain.Slide18
High Frequency SCS
Paresthesia free
High frequency (10k Hz), low amplitude, short duration.
Mechanism is not known
Mitigates overall excitability, reduces dorsal horn neuron activity
Does not require paresthesia mapping, more forgiving to lead migration, less vulnerable to body position changes.Slide19
Landmark studies for SCS (for FBSS)Slide20
SCS for CRPS
Limited high quality data
Kemler
et al
6 month history of CRPS randomized to SCS + PT vs PT alone
At 2 years – SCS + PT group had reduction in pain and higher satisfaction.At 5 years – effect diminished over time. Despite the diminishing effectiveness of SCS over time, 95% of patients with an implant would repeat the treatment for the same result.Slide21
SCS for Ischemia and Angina
Widely used outside the united states, but now recently starting to be approved by certain insurance plans.
Treatment for vasospasm/
raynauds
specifically.Slide22
Burst SCS evidence
Tends to be limited by duration of follow up.
DeRidder
et al (2013)
Burst SCS is superior to placebo in decreasing axial and limb pain.
Burst SCS superior to tonic SCS in suppressing axial pain (but not limb pain)1w f/uDe V0s et al (2014)Patients who had received tonic SCS for 6 months. 3 subgroups (FBSS good responders to tonic SCS, FBSS poor responders to SCS, and PDN)All experienced pain relief when switched to burst mode for 2 weeks.44% better pain relief in PDN patients, 28% better relief in FBSS.2w f/uSlide23
HF-10 SCSSlide24
SCS is also more cost effective
Kumar (2002)
60/104 patients with FBSS implanted with SCS
5 year follow up:
SCS - $29k over 5 years
Control - $38k over 5 years (ER, radiology, physician visits, medications)Kemler (2002) SCS for CRD36/54 patients with CRD implanted with SCS/PT vs PT aloneSCS is $4k more expensive in first year, but saves $60k in lifetime analysis.Projected lifetime analysis , using complication rates of 30%RSD costs are generally medical care, PT, transport, DME, and medication.Slide25
Thank you!