Spinal Cord Stimulation: What Clinicians Need to Know
Proper patient selection is crucial to successful use of spinal cord stimulation (SCS) in pain management, but the timing of SCS, the location of lead placement, and the type of stimulator used also are important factors.
“Spinal cord stimulation is an ideal tool for the right patient, including patients with chronic radicular pain, axial pain who are not surgical candidates, [and patients with] failed back surgery or complex regional pain syndrome,” explained Michael B. Furman, MS, MD, Partner at OSS Health in York, Pennsylvania.
Dr. Furman chaired a panel discussion on SCS at the 31st Annual Meeting of the North American Spine Society (NASS), recently held in Boston, Massachusetts.1 The session reviewed patient selection, advancements in SCS technology, and tips for integrating SCS into a surgical practice. This article will review highlights of the panel discussion. (Fore more highlights from NASS, click here.)
Guidance on Patient Selection
Patient selection and the timing of SCS placement are both crucial to success of the procedure. The patient selection process involves psychological screening, possible thoracic imaging, consideration of medical history, and an SCS trial. Despite the importance of psychological screening before SCS implantation, Dr. Furman noted that many physicians may not appropriately incorporate these screens into the patient evaluation process. While thoracic advanced imaging is not necessarily considered a standard of care for patient selection, Dr. Furman said that he often performs thoracic imaging because he has experienced a few cases in which an obstruction prevented him from passing an SCS lead.
Medical history is crucial, providing information about use of anticoagulation therapy, a relative contraindication, as well as any history of traumatic spinal cord injury, lead migration, and infection.
The SCS trial is another important part of the selection process, Dr. Furman emphasized. As part of this trial, the physician must decide whether to use 1 or 2 leads. This decision depends on a number of factors, including whether the patient had bilateral or unilateral pain, as well as physician preference.
For percutaneous lead placement, Dr. Furman recommended using the fluoroscopic contralateral oblique view, which he called the “safety view,” because it allows visualization of anatomical locations that should be avoided.2
Given the high placebo response rate with SCS trials, which Dr. Furman noted could be as high as 40%, a longer trial duration (5 to 7 days) may help avoid assessment during the “honeymoon phase.” In addition, he explained that some patients will do anything to get better and, thus, may say that they improved during the trial when little symptomatic improvement actually occurred. “You want to walk away from the trial with both you and the patient convinced that they did well with the procedure,” Dr. Furman said.
Temporary vs Permanent Percutaneous Leads
The benefits of using temporary percutaneous leads during SCS trials include reversibility and low morbidity. These leads can be placed and anchored to the skin in an outpatient setting by the surgeon or pain management specialist, explained NASS President Todd Wetzel, MD, a professor of orthopedic and neurological surgery at Temple University School of Medicine in Philadelphia.3 After initial placement of a temporary percutaneous lead, “you can retract the lead a little bit and map it with different real-time paresthesia responses, and get a better guide of where to put the permanent lead,” said Dr. Wetzel.
On the other hand, Dr. Wetzel said, “If I’m convinced that the patient is going to do well with SCS, I put in a permanent percutaneous lead for the trial, with a temporary lead extender placed out to the side, and the patient takes antibiotics for 10 days. If it is a positive trial, the patient goes back to the operating room; I don’t have to move the lead, but rather just remove the temporary extender, tunnel, and put in the pulse generator.”
Dr. Wetzel said he prefers the latter approach, given that it is difficult to place the permanent lead in the exact same place as the temporary lead. He added that approximately 50% of his SCS trials involve permanent percutaneous placement.
The SCS trial also can be performed surgically using a laminotomy, a procedure that Dr. Wetzel said has become easy to perform. This approach requires a general anesthetic with motor and sensory monitoring, and somatosensory evoked potentials or electromyographic mapping.
Dr. Wetzel emphasized the importance of anchoring the SCS lead to the fascia using multiple nonabsorbable sutures. He noted that finding the fascia can be difficult in patients with a body mass index greater than 30 kg/m2. In these patients, he said, “Don’t be afraid to make a ... bigger incision if you have to get to the fascia because it will pay dividends.”
Care for permanent lead placement should involve preoperative antibiotics with no further antibiotics required except in cases of higher-risk patients.
Factors to consider before permanent implantation include whether to use a primary cell (non-rechargeable) device or an SCS with a rechargeable battery. “A good rule of thumb I use in the office is to ask patients if they can use a remote control for their TV or if they use rechargeable batteries for their electronic devices,” Dr. Furman said. “If they are unable to use a remote control or rechargeable batteries, they will most likely be unsuccessful with a rechargeable system.”
In addition, it is important to review patient expectations before permanent SCS implantation. “With reasonable expectations, SCS can work well,” Dr. Furman said.
Advancements in SCS Technology
There are several SCS approaches to consider, depending on whether the goal is to create pain relief with paresthesia (conventional SCS) or without paresthesia using a newer approach with 10 kHz high-frequency stimulation and anatomic lead placement (HF10 SCS). In the latter approach, the clinician uses an external trial generator during the trial that is controlled by the patient. In addition to HF10 SCS, other new trends include burst stimulation and expanded indications for dorsal root ganglion (DRG) stimulation.