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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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PEARLS

Routine administration of prophylactic antibiotics is warranted prior to spinal cord stimulator implantation, as any infection that does occur may extend to involve the neuraxis. Appropriate agents include cefazolin 1 to 2 gm IV 30 minutes prior to incision, clindamycin 900 mg IV 30 minutes prior to incision, or vancomycin 1 gm IV over 60 minutes prior to incision.

It is important to discuss the location of the impulse generator with the patient prior to surgery and mark the site using a skin marker with the patient in the sitting position. Be sure to consider each patient’s daily activities when selecting a location. For instance, mechanics who spend much time leaning forward with their abdomen against a vehicle may be bothered by an impulse generator located in the abdominal wall.

Dural puncture is a significant risk during the procedure, and the particular needle used for placing the spinal cord stimulator lead often does not give a clear sign of loss of resistance during advancement. In such cases, advance the needle using fluoroscopic guidance and seat the needle tip on the margin of the lamina immediately inferior to the interspace you are attempting to enter. In this way, the depth of the lamina is certain, and loss of resistance is needed only during the final 3 to 5 mm of needle advancement, reducing the risk of dural puncture. In the event dural puncture does occur during lead placement, consider rescheduling the procedure or moving to an interspace more cephalad for lead placement. Postdural puncture headache is a near certainty with the large-bore needle used for electrode placement, so be prepared to offer treatment as needed, including an epidural blood patch. Performing an epidural blood patch in the days immediately following spinal cord stimulator implantation has been described, but the risks associated with the approach are uncertain.

To minimize the risk of lead migration, provide a secure anchor for the lead. The most important point during implantation is securing the lead to the paraspinous fascia. First, extend the incision deep enough to expose the fascia; securing the lead to loose subcutaneous tissue or fat is inadequate. Once the fascia is exposed, place the lead anchor supplied by the manufacturer over the lead and advance the anchor to the point where the lead enters the fascia. Securely fasten the lead anchor to the lead itself, first using sutures around the anchor and lead only. After this is accomplished, you should no longer be able to slide the anchor over the lead. Then suture the lead and anchor securely to the fascia. Postoperatively, advise patients to avoid bending or twisting for at least 4 weeks after implantation; place a soft cervical collar for those with cervical leads for comfort and as an effective reminder to avoid movement.

It is also important to ensure that the size of the pocket created for the impulse generator is adequate to prevent tension on the suture line following wound closure. Similarly, use caution when placing the fascial closure sutures. Know where the lead lies at all times to avoid damaging it with the suture needle.

It is good practice to obtain anteroposterior and lateral radiographs of the spine following successful lead placement. The radiographs can serve as a helpful reference when attempting to produce a similar pattern of stimulation during subsequent lead placement or when trying to determine if the lead has migrated. Loss of stimulation may signal lead migration or fracture. Check lead impedance first to detect a lead fracture. Thereafter, radiography and comparison with films obtained at the time of initial lead placement are used to detect lead migration.

Impulse generator battery failure is inevitable and occurs over a broad range (about 1–4 years), depending on the stimulation parameters and frequency of use. Approaching battery end-of-life typically begins with intermittent malfunction of the device; the most common malfunction is the device shutting off on its own.

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