Chapter 71: Spinal Cord Stimulation: Implantation Techniques

INTRODUCTION

Electrical stimulation of neural structures is a widely used, nondestructive, reversible therapy, for chronic noncancer related pain. It has been evolving rapidly since the “gate theory,” developed by Melzack and Wall in 1965, which opened the door for this application. Neurostimulation may modulate pain pathways at the central nervous system and peripheral nervous system levels. Various techniques and technologies have been developed according to the site of stimulation: spinal cord stimulation (SCS), deep brain stimulation (DBS), motor cortex stimulation (MCS), large peripheral nerve stimulation (PNS), peripheral nerve field stimulation (PNFS), and more recently dorsal root ganglia stimulation (DRG-S). This chapter looks at percutaneous surgical techniques of electrical stimulation of the spinal cord.

INDICATIONS

Chronic neuropathic pain affects a significant percentage of the population and is often inadequately treated. It may result in low quality of life, medication overuse, and worsening of mood disorders. The FDA has approved SCS as an instrument in treatment of chronic intractable pain of the trunk and limbs including unilateral or bilateral pain associated with postlaminectomy syndrome, intractable low back pain and leg pain. Besides neuropathic, low back and limb pain there is evidence for off-label use of SCS for ischemic pain in refractory angina and peripheral vascular disease and some evidence for effectiveness in visceral pain. The indications of SCS are:

• Neuropathic pain in upper or lower extremities related to postlaminectomy syndrome (so-called failed back [neck] surgery syndrome—FBSS or FNSS)

• Complex regional pain syndrome (type I/II)

• Radiculopathy

• Plexopathy: traumatic (partial), postradiation

• Arachnoiditis

• Painful peripheral neuropathy including idiopathic small fiber neuropathy, metabolic (diabetic), infectious (HIV), and toxic (chemotherapy-induced) neuropathy

• Stump pain (postamputation)

• Ischemic pain associated with peripheral vascular disease

• Ischemic pain associated with refractory angina

• Visceral pain

  SCS indications associated with lower success rate

• Axial pain following spine surgery (back and neck)

• Postherpetic neuralgia pain

• Phantom pain

• Post-thoracotomy pain

• Incomplete spinal cord injury with complete or clinically distinguishable loss of posterior column function

• Central pain

As discerned, many of the poorer responsive conditions encompass deafferentation features of pain.

CONTRAINDICATIONS

• Any contraindication for regional anesthesia such as uncorrected coagulopathy or infection

• Pregnancy (though there are reports of uneventful pregnancies and deliveries on SCS)

• Severe central canal stenosis

• Neurologic deficit that would likely be amenable to surgery

• Significant/progressive spine instability

• Need for frequent follow up by magnetic resonance imaging as in multiple sclerosis

• Unacceptable surgical risk

• Cognitive impairment

• Active substance abuse

• Implanted pacemaker or AICD (though off label use of SCS in this setting has been reported)

• Borderline personality disorder or other psychiatric co-morbidities that preclude success

• Previous lesion of dorsal root entry zone

Documentation for Off-Label Indications

Documentation for off-label use should include a detailed discussion with the patient. The physician may discuss representative original publications, review articles, book chapters, or technological review assessments, which detail the effectiveness ...