2018 FSA Posters

P050: SAFE PERIOPERATIVE MANAGEMENT OF SPINAL CORD STIMULATORS
Timothy V Feldheim, MD, Richa K Sutaria, MD, Rene Przkora, MD; University of Florida College of Medicine

Introduction: As neuromodulation plays an increasingly vital role in chronic pain management, spinal cord stimulators (SCS) are becoming more prevalent. SCS is FDA approved for complex regional pain syndrome, failed back surgery syndrome and chronic neuropathic.1 Leads are placed surgically in the dorsal epidural space under fluoroscopy, and tunneled subcutaneously to an implantable pulse generator (IPG). The SCS generates electrical activation of the dorsal roots afferent nerve fibers, which inhibits nociceptive pain resulting in diminished perception of pain according to the Gate Control Theory.2 Almost 34,000 patients undergo SCS implantation annually.3 However, there is no consensus on safe perioperative management of SCS.4

Methods: A systematic literature review was performed using PubMed using the phrase “Spinal Cord Stimulator Safety.” Also the websites of the 5 major SCS device manufacturers* were accessed and the manuals reviewed.

Results: Pre-intervention, SCS should be reprogrammed to lowest possible setting and then turned off.4-5 This is done to avoid complications stemming from inadvertent firing of devices secondary to electrical or radiofrequency interference. Should the device activate, it will fire at the lowest setting. 4-5, 7-11  Some devices now have s pre-programmed surgery and MRI modes. Post-intervention, devices should be re-interrogated to assess for failure or damage.6

If using electrocautery, it is advisable to avoid unipolar to prevent dispersive electric current passing through the device. 4-5, 7-11 If unipolar must be used, the grounding pads should be placed away from leads and IPG, and in a path that does not cross the device.4 This should preferably be done on the contralateral side to reduce risk of harm to device and patient.4 The same ought to be applied for bipolar electrocautery as the grounding pad works as a fail-safe if the bipolar setting fail.4

No adverse events have been reported using Lithotripsy and High Output Ultrasound. Almost all manufacturers recommend focusing the beam at a distance greater than 15 cm away from the SCS. 4

It has been recommended to avoid neuraxial anesthesia in patients with implanted SCS devices.2,4 This is due to the risk of  infection to the hardware, damage of, or causing lead migration of the SCS, thus knowing lead location is vital if NA is used.2,4 There has also been at least one case report of failed neuraxial anesthesia in a patient with a SCS.4

SCS MRI compatibility is dependent on the manufacturer and model.4 Some are fully compatible while others are restricted to imaging of trunk and extremities.4,7-11 MRI can cause lead migration, heat damage, and decreased efficacy of SCS.4,7-11 Providers should check make and model prior to obtaining MRI’s of patients.4

Conclusion: SCS are prevalent, and anesthesiologists should be aware of hazards that SCS can cause if not safely managed perioperatively. Prior to interventions, SCS devices should be reprogrammed to appropriate settings or turned off. It is essential to interrogate the device post intervention to ensure proper functioning. Different interventions carry different risks for potential harm to the patient and device, which makes provider awareness of SCS hazards imperative in the perioperative period