FRCA Notes

Spinal Cord Stimulators

Resources

  • Chronic neuropathic pain >6months and pain score >5/10 despite optimal conventional medical management, following successful trial of stimulation
  • Examples include:
    • Failed back surgery syndrome e.g. for refractory lumbar radiculopathy
    • Complex regional pain syndrome
    • Chronic pain of ischaemic origin (either a continuation of existing therapy or as part of a trial)
      • Chronic lower limb ischaemia
      • Chronic, refractory angina pectoris

  • Systemic infection or sepsis
  • Existing implanted medical (cardiac) device e.g. PPM, ICD
  • Immunosuppressed state
  • Uncontrolled bleeding or anticoagulation
  • Psychological unsuitability e.g. severe depression, anxiety, personality disorder

  • A pulse generator is placed externally for the trial period
  • If successful, implanted internally in the subcutaneous space e.g. abdominal wall, gluteal, infraclavicular areas

  • Implanted electrodes (stimulator leads)
    • 4-8 electrodes
    • Either catheters (percutaneously placed) or paddles (surgically placed)
    • Lie in the epidural space over the dorsal columns, typically in the thoracic spine

  • The exact placement of leads in the epidural space varies depending on the clinical condition being treated

Mode of action

  • The stimulator provides electrical stimulation to the dorsal columns, lateral funiculus and dorsal roots
  • This stimulation depolarises and inhibits afferent ascending nociceptive pathways and also increases supraspinal descending antinociceptive pathways
  • The strength, duration and frequency of the electrical impulses are programmed remotely and can be altered by the patient

Pre-operative

  • If needed, pre-operative discussion with pain/neuromodulation team
  • Generally advised to switch off, although no clear evidence of why

Intra-operative

  • Avoid unipolar diathermy
  • Careful positioning to avoid damaging the pulse generator

  • Risks with neuraxial anaesthesia
    • Damaging the leads
    • Displacing the leads
    • Infection of the leads - no routine antibiotic prophylaxis advised, however
  • Therefore avoid neuraxial anaesthesia

Post-operative

  • Switch device back on
  • No role for management of acute nociceptive pain so should manage this separately as standard