Spinal Cord Stimulation Periprocedural Care
- Author: Anthony H Wheeler, MD; Chief Editor: Kim J Burchiel, MD, FACS more...
Following completion of a SCS percutaneous trial, the leads are pulled, and the skin entry sites are cleaned with chlorhexidine and alcohol. A topical antibacterial agent can be used to cover the puncture sites, then a Tegaderm dressing is applied as an additional barrier.
The permanent trial is scheduled for no sooner than 2-3 weeks, after which any inflammatory or infectious residua should be resolved. This also allows time for recognition of all potential trial complications, so that they be treated and not increase the risk of complication of permanent SCS placement. The required lead length to the IPG pocket site is measured, any imaging studies that would expose an anatomical or technical barrier are requested, and pertinent preoperative blood work should be considered to preclude infectious or bleeding complications.
Limited research using computer modeling analysis suggested that the effect of spine flexion on the distance between an IPG site implanted in the buttock and the midline anchor requires an increased lead length of 9 cm. Therefore, strain relief loops 2.5-3 cm in diameter are placed at appropriate sites to compensate for spinal movement (adjacent the midline anchor and a second loop adjacent the IPG pocket). Each loop requires an additional 9-10 cm of lead length. These strain relief loops reduce kinking, damage, and breakage of the leads.
Conversely, modified direct tunneling techniques that travel diagonally, directly to the IPG pocket, require comparatively reduced lead length. Experts and the literature are unsettled as to a specific "best" approach (eg, gluteal, abdominal, or midline placement in lumbar cases or various axillary sites in cervical placements). Some implanters prefer to tunnel cervical placements to the gluteal, abdominal, or lateral hip region. A common lead length when tunneling directly to the IPG pocket while also allowing for adequate strain relief is 70-cm. For longer permanent leads, most manufacturers provide supplemental extensors.
Proper placement of the IPG site is performed preoperatively. The site should be in a comfortable area within the patient’s reach for recharging. Postural change should be considered so that comfort is achieved both sitting and standing. A model of the IPG is used during pocket formation, a tight fit that requires some soft tissue stretching is preferred to minimize any dead space around the battery. For example, preparing a male patient for a gluteal pocket is best performed with the patient wearing pants so that the surgeon or technologist can locate a site using a model IPG placed over the skin. Preferred placement is below the belt line, yet high enough so that the unit does not impede sitting or reclining.
Similarly, female patients should wear a bra so that the IPG model can be located under the bra line. The IPG model is outlined using an indelible marker for precise location during the procedure (see the image below). The goal is to create a pocket that matches the size of the IPG as closely as possible. The incision site will be placed at the superior edge of the battery pocket. Location should be discussed with and approved by the patient.
For this procedure, the patient lies prone on the fluoroscopic table, which allows free access to the C-arm throughout the entire thoracolumbar spine. The patient’s head should be turned to the side so that most of the neck and back are relaxed. The vertebral column is positioned to minimize cervical or lumbar lordosis as described above, by placing pillows or specialized surgical bolsters or frames under the abdomen or chest that allow adjustable flexion for comfort. Additional pillows and modifications should be used to allow the patient to be comfortable and warm before the patient’s back is scrubbed with antiseptic and draped.
Specific landmarks are used to identify the needle entry point. The most desirable oblique angle for needle placement is 30-45°. After fluoroscopic alignment of the pedicles and vertebral end plates, previously described, anatomic references, including the intralaminar entry site should be horizontal, crisply outlined, and clearly identified. For most percutaneous trials of the lower back and legs, the preferred entry for distal lead placement is usually between the T12-L1 and L2-3 intralaminar spaces.
The medial aspect of the ipsilateral pedicle 1-2 levels below the intralaminar entry target at the 9 or 3 o’clock position are marked as the skin entry site or sites.
In an average-sized adult, skin entry between L2 and L3 is technically safest because the conus medullaris and spinal cord are cephalad to this level in most adults. When the insertion point is selected, the tip of a metal marker is placed over the point to provide a fluoroscopic landmark. Adjustment of the entry point may be necessary in patients with extremes in body habitus. Entry will be more cephalad in very thin patients and caudal in very obese patients.
Monitoring & Follow-up
The SCS system is retested in the recovery room to assure that no lead migration or fracture may have occurred and that coverage remains adequate. If coverage is not acceptable, then the patient is taken back to the OR for revision. Over the next 24-hours neurological signs and symptoms are monitored. Any postoperative observations, including pain, weakness, or numbness, should be investigated. Paresthesia should be evaluated despite the device being turned off.
Postoperatively surgical wounds are dressed with nonocclusive bandages. Dressing changes are indicated when they become wet or bloody. Wet dressings should raise concern for fat necrosis in obese patients. Although the scientific literature is conflicting, conventional instruction has been to keep the wound dry for 10-14 days or until 1-2 days following suture/staple removal.
The first postoperative check is usually indicated at 3-4 days, whereby, the outer dressing is removed for wound inspection. Loose Steri-Strips are removed, but intact strips are left in place. Loose materials are irrigated with peroxide, and then the wound is gently patted dry with a 4x4 sterile cotton gauze pad. Next, a 4x4 sterile cotton gauze pad is loosely taped over the healing wound. At postoperative days 7-10 days staples/ sutures are removed, the final postoperative visit is usually scheduled at 3 weeks. If the wound shows no signs of infection, the patient may bathe.
Patients are advised to avoid bending, squatting, or reaching above the shoulders for 6-8 weeks following surgery. Patients are asked to avoid twisting, limit lifting to less than 5-8 pounds, and to refrain from sleeping on their stomach. Motor vehicle accidents and trauma, like falls, can threaten lead integrity. Confronting a magnetic environment may induce current flow through coiled electrodes or lead extensions. Magnetic fields are commonly encountered through theft-deterrent devices, metal detectors, airport security procedures, and with medically indicated magnetic resonance imaging studies. Diathermy can cause tissue damage through energy that is transferred into the implanted SCS components resulting in severe injury or death.
During the healing period, the relationship between the implanted electrode surface and adjacent tissues evolves through healing, scarring and systemic/ metabolic factors. Therefore electrode contact and impedance changes can be expected. Manufacturer representatives are expected to stay in touch with postoperative patients to determine SCS efficacy when the system needs to be recalibrated or reprogrammed for improved pain coverage. Over the 6-8 weeks following SCS placement, physicians must manage medication-intake or tapering and patient expectations regarding pain relief.
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