Spinal Cord Stimulation Benjamin Bonte, MD - PowerPoint Presentation

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!