New Developments in Spinal Cord Stimulation
Technological advances in spinal cord stimulation (SCS) represent some of the most exciting developments in pain management. The gate-control theory, which proposes that activation of non-nociceptive fibers prevents painful stimuli from reaching the thalamus, serves as the basis for SCS. Devices that deliver SCS have evolved over the years from large instruments with batteries lasting 3, 5, or 10 years—later with rechargeable batteries—to miniaturized devices with multiple smaller leads and configurations. This technique has proved particularly useful for patients with complex regional pain syndrome, who present some of the greatest challenges for physicians who seek to relieve patient pain. Symptoms of this disorder, including swelling, loss of motion, and extreme sensitivity to light touch, are tremendously relieved by SCS, and the Neuromodulation Therapy Access Coalition has assigned a Grade A recommendation supporting use of SCS for patients with complex regional pain syndrome. A new technique, dorsal root ganglion (DRG) stimulation, involves placement of the stimulator directly on the DRG through an epidural (inside out) approach and selective stimulation of different parts of the DRG, providing superior treatment outcomes for many patients. For patients who find the traditional paresthesias associated with tonic SCS to be very painful, even intolerable, and for those who have developed tolerance to SCS, revolutionary new treatments are proving tremendously successful in providing pain relief. Burst stimulation offers SCS placement at higher levels of the spine and use of alternative waveforms, in which neurons fire in bursts, followed by periods of dormancy, leading to pain reduction without painful paresthesias. In combination with conventional tonic stimulation, burst stimulation represents a comprehensive approach to effective pain management. Additional exciting developments in this field include (A) high-frequency SCS, a novel SCS system that allows a pulse rate up to 10 kHz with more efficient anatomic positioning, providing paresthesia-free pain relief; (B) percutaneous leads and paddles, which permit tailored stimulation patterns for patients with chronic pain; (C) magnetic resonance imaging-compatible SCS systems, which allow magnetic resonance imaging scans on hips, shoulders, back, and elsewhere, without concern about lead heating, device damage, unintentional stimulation, and magnetic pull; and (D) battery-free SCS, which transmits energy wirelessly from an external unit. Recent developments in the field of SCS and devices and approaches of the future, although not curative, are expected to continue to significantly relieve pain and promote activity postoperatively, and among those whose cause of pain cannot be identified, for better outcomes and improved quality of life.