SCS and IDDS: Patient Selection

Marshall D. Bedder M.D., F.R.C.P. (C)

Director Interventional Pain

Pacific Medical CentersSeattle, WA

SCS/ IDDS

Pain Management:A More Flexible Approach

NSAIDs,over-the-counter

drugs

Physical therapy,

TENS

Corrective surgery

Long-termoral

opioids

SCS

IDDNeuroablation

Chronic Pain

Patient

Complementary medicine, behavioral

programs,adjuvant

meds

* Prager J and Jacobs M. Evaluation of patients for implantable pain modalities: medical and behavioral assessment. Clin J Pain. 2001 Sep;17(3):206-14.

• Different time frames • Multiple therapies at one time • Different starting points

IDDS

IDDS: Patient Selection

• Severe spasticity

• Chronic intractable cancer pain

• Chronic intractable non cancer pain

Synchromed II Drug Infusion U.S. FDA approved Indications

• Preservative free Morphine in the treatment of chronic intractable pain

• Ziconotide for severe intractable pain

• Baclofen for severe spasticity

Criteria

• Antispasmodic drugs for severe spasticity• Chronic intractable spasticity• Unresponsive to to less invasive medical

therapy• Usually a 6 week trial of oral antispasmodic

drugs• Responds favorably to a trial of intrathecal

baclofen

Criteria

• Chronic Intractable Pain Severe chronic intractable cancer or CNCP Life expectancy of at least three months Functional disability Increasing pain and side effects despite rotating oral

opioids Surgery is ruled out No active or untreated addiction Lack of contraindications Psychological assessment for appropriateness Successful trial

SCS

Spinal Cord Stimulation(SCS)

Patient Selection

SCS FDA Indications

• Difficult to treat chronic pain of the body and limbs

• Pain associated with failed back surgery syndrome

• Low back pain and leg pain.

SCS Indication

• Intractable pain of the trunk and/or limbs-including unilateral or bilateral pain associated with the following conditions:

• Failed Back Syndrome (FBS) or low back syndrome or failed back

• Radicular pain syndrome or radiculopathies resulting in pain secondary to FBSS or herniated disk

• Multiple back operations, Unsuccessful disk surgery

• Degenerative Disk Disease (DDD)/herniated disk pain refractory to conservative and surgical therapies

• Peripheral causalgia

• Complex Regional Pain Syndrome (CRPS), Reflex Sympathetic Dystrophy (RSD), or causalgia

Neuropathic PainNeuropathic Pain

• Caused by damage to the peripheral or central nervous system or by pathologic changes in neuro-functional relationships within these systems

• Pain most often described in terms:

• Tingling• Burning• Shooting, lightening like

Neuropathic Pain (cont)Neuropathic Pain (cont)

• Often opioid resistance with a rightward shift of dose response curve

• Examples include:SciaticaPhantom limb painPostherpetic neuralgiaComplex regional pain syndrome (CRPS)Diabetic neuropathy

Neuropathic PainNeuropathic Pain

• Central sensitization

• Wind-up

• Role of NMDA and other receptors

Evidence for IDDS

• Pro Good evidence for

spasticity Good evidence for

cancer pain

• Con Thimineur et al. Pain 2004 June.

Three year prospective study. Showed that when patients with

extremely severe pain problems are selected as pump candidates, they will likely improve, but their overall severity of pain and symptoms still remains high

Evidence for IDDS

• The systematic review by Patel et al (ASIPP) 2009 was unable to find any randomized trials evaluating the effectiveness of intrathecal infusion systems on a long-term basis. Consequently, a decision was made to develop consensus guidelines.

Effects of SCS on Sensory SystemsEffects of SCS on Sensory Systems

CentralNon-segmentalSegmental

Electrical Chemical

Lamina I, II Lamina V

Electrical Chemical

NorepinephrineDopamine

Depolarization of large diameter fibersAntidromically conducted AP’s

Frequency-related conduction blockHyperpolarization effect (anodal)

?

Attenuation of SSEP’sThalamic activation (VPL, CM)

GABAGlycine

5-HTsubstance P