1. Spinal Cord Stimulation
Mahmoud N. Sabbagh M.D.
Physical Medicine & Rehabilitation
Pain Management

2. OBJECTIVES What is spinal cord stimulation
How spinal cord stimulation works
Candidates for spinal cord stimulation
Long term outcomes of spinal cord stimulation

3. SPINAL CORD STIMULATION
2500 B.C., ancient Egyptians used electrogenic fish to relieve painful sites
Ancient Romans documented 1st medical reports of using black torpedo fish’s electrical discharges to relieve pain

4. SPINAL CORD STIMULATION
Dr. Norman Shealy reported the first successful case of spinal cord stimulation in 1967
He treated neuropathic cancer pain by placing a lead in the intrathecal space

5. GATE CONTROL THEORY
Melzack and Wall proposed Gate Control Theory in 1965.
Non-painful inputs closes “gate” on painful inputs, reducing pain signals traveling to the CNS
Aδ, Aβ and C fibers all synapse at the dorsal horn
Aδ and C fibers transmit pain
Aβ fibers transmit light touch and pressure

6. GCT

7. SPINAL CORD STIMULATION
Aδ fibers are myelinated and perceive immediate, sharp pain (40mph)
C fibers are non-myelinated and perceive longer lasting deep, throbbing pain (1-3 mph)
If the gate is overwhelmed by Aβ fibers, input for C and Aδ fibers will reduce.

8. Mechanism of Action
SCS inhibits dorsal horn WDR neurons excitability, increased GABA, decreases release of excitatory neurotransmitters
Hyper excitability of WDR neurons after nerve injury found to be due to dysfunction of GABA system & increased release of excitatory neurotransmitters

11. Patient Selection & Pre-Op Considerations
Diagnosis amendable to therapy
Failed conservative therapy for at least 6 months
Significant psychological issues ruled out or controlled
Trial has demonstrated effectiveness
Pre-operative establishment of functional goals
Images carefully reviewed, severe spinal stenosis of T/C spine increases risk for cord compression from lead

12. Indicators for poorer outcomes
Opioid Use Disorder
Untreated Psychiatric and Psychological diseases
Inability to understand risks and benefits of SCS
Presence of bleed abnormalities
Physician impression that the patient is a poor candidate

13. Indicators for best outcomes
Radicular or neuropathic pain after spinal surgery
Spinal nerve entrapment conditions
Complex Regional Pain Syndrome
Painful neuropathies
Refractory angina
Ischemic limb pain or pain related to PVD
Achievement of paresthesia in the area of pain during trial phase

14. CONTRAINDICATIONS Uncorrected coagulopathies Current infection
Inability to control device of lack of cooperation
Thoracic syrinx
RELATIVE CONTRAINDICATIONS
Thoracic spinal canal stenosis (<mm for percutaneous lead)
Cardiac Defibrillator/Pacemaker (cardiology consultation recommended, most pacemakers are now compatible)

15. COMPLICATIONS Infection Post Dural puncture headache
Spinal cord injury
Nerve injury
Lead fracture
Lead migration
Most common complication which may result in loss of stimulation in the desired areas. The incidence of lead migration has been reducing with improvement in techniques and equipment and is now at approximately 13%

16. Equipment
Platinum alloy electrodes placed in posterior epidural space to electrically stimulate the dorsal columns
Two types:
Percutaneous Leads: flexible, cylindrical polyurethane catheters with platinum alloy electrodes
Due to their cylindrical design, they generate a circumferential current flow. This may cause uncomfortable stimulation of ligamentum flavum

17. EQUIPMENT Paddle leads: flat, wide with insulation on one side
Current flow is unidirectional
More invasive, laminotomy or laminectomy
Optimal when considering migration or anatomy
Power source: Rechargeable IPG (implantable pulse generator). Contains lithium ion cells with a 10 year life span.

18. TRIAL PHASE Leads are implanted and secured to the skin
Allows for test stimulation of several days
Determine if SCS is appropriate therapy for patient

19. Spinal Cord Stimulation* * *
Slide Objective
Introduce spinal cord stimulation
State/Ask
Content
State
Spinal Cord Stimulation
One of the spinal cord stimulating devices is call Spectra from Boston Scientific
Cordless
Remote Control
Cordless
Charger
Implantable Pulse
Generator (IPG)

20. Programming Amplitude: Pulse width: Rate/Frequency:
Generally perceived by the patients as the intensity of the paresthesia but may also correlate with the total area of paresthesia generated
Increasing the amplitude will increase the total number of fibers recruited by the electrical stimulation
Pulse width:
Increase number of activated fibers.
May result in increased paresthesia coverage
Rate/Frequency:
Impulse perception

22. Medial: lateral: Attention to pain location, type & intensity to pain
Medial pathways more sensitive to burst firing
Medial: lateral: Attention to pain location, type & intensity to pain

23. DRG STIMULATION
Devices to stimulate the dorsal root ganglion (DRG) became available in the mid-2010s for treating chronic pain, particularly in areas that were hard to treat with traditional spinal cord stimulation, such as the hand, chest, abdomen, foot, knee or groin