Spinal Cord Stimulator

Theory Behind Spinal Cord Stimulators

Gate Control Theory

The Gate Control Theory is a plausible explanation of why spinal cord stimulators are effective.

SCS increases input through the large nerve fibers (A-alpha), hence closing the gate at the substantia gelatinosa of the dorsal horn of the spinal cord; consequently, it may increase GABA (inhibitory) and decrease the excitatory neurotransmitters glutamate and aspartate

The patient usually undergoes a 5-7 day pretrial to evaluate the effectiveness of a possible permanent implant

Indications for SCS

• Failed back surgery syndrome
• Neuropathic pain syndrome
• Failure of conservative therapy
  • Failed polypharmacy (anticonvulsants, antidepressants, and/or opioids)
• Pain relief with trial
• Chronic pain for > 6 months

Complications

Nerve and spinal cord injury

Infection

Hematoma

Lead breakage or migration

Anesthetic Considerations

Pain control can be challenging during surgery

Difficulty with positioning

Prone position

MAC anesthesia as the patient needs to be awoken to evaluate the effect during the procedure

Restricted access to the airway

Chronic pain = decreased physical activity = decreased respiratory/cardiac reserve

Document any pre-existing neurological defects

Neuroleptic malignant syndrome

• Patients on antipsychotic medication may develop neuroleptic malignant syndrome.
• Onset after hours/months of treatment, potentially fatal
• Hyperthermia, muscle rigidity, tachycardia, HTN, agitation, and acidosis
• Treat with bromocriptine (increases dopamine levels, Dantrolene (decreases Ca levels), or diazepam
• Mimics malignant hyperthermia

DIFFERS from serotonin syndrome as that has myoclonus - seen with MAO-B inhibitors = increased levels of dopamine in the brain. Concomitant use of Meperidine and antidepressants can cause serotonin syndrome, which can lead to coma and death.

Decreased gastric emptying

• Consider Reglan

Obesity due to decreased physical activity