Procedural Complications

Common potential procedure-related complications surrounding PNS procedures involve tissue trauma, infection, allergic reactions, and anesthesia-related complications. In general, avoidance of such complications necessitates high-quality fluoroscopic guidance to promote optimal lead placement, as well as meticulous surgical technique to prevent infection from contaminated skin, implanted equipment, and other causes. However, development of complications from PNS procedures is still possible even with extensive preventive measures, use of technologically advanced equipment, and years of practitioner expertise.

Harm caused to tissues during PNS procedures may consist of bleeding, peripheral nerve trauma, and damage to vital structures (e.g., vessels and organs). Because vital internal structures are vulnerable in PNS, the use of high-quality fluoroscopy is indicated; for example, pneumothorax, a potential organ-related complication of PNS device installation in the thoracic region, is best circumvented by high-quality imaging.⁶ In deeper tissues, damage to vessels can be evaded by using an open rather than percutaneous technique, which may help to prevent blind injury of vasculature, embolism, and other negative sequelae.

Hemorrhage is a potential adverse outcome in any surgical procedure. In PNS, bleeding can occur in the region of the generator or lead incision, promoting hematoma and wound dehiscence. In some instances, serosanguineous fluid rather than blood may accumulate, leading to seroma. Both of these problems are limited to the area of surgery and do no usually result in life-threatening disorders.

Because the risk of excessive bleeding and seroma development exists, standard precautions against hemorrhage and fluid leakage should be exercised. Specifically, in the preoperative period, patients should discontinue medications likely to promote bleeding, and patients with a history of excessive bleeding should have a coagulation profile performed. During the procedure, the practitioner should focus on careful tissue dissection, containment of bleeding, and thorough inspection of the wound before closure. In addition, expert surgeons recommend irrigation and complete closure of surgical wounds to diffuse any sources of infection and restriction of pocket size to no larger than necessary to inhibit seroma formation.

The use of PNS therapy was commonly used to treat pain after previous nerve damage as described by Mobbs et al⁴ in their retrospective study (currently the largest in the literature) of 38 patients implanted with 41 nerve stimulators. The previous nerve damage included blunt and or sharp nerve trauma (in 14 of 38 patients) and inadvertent injection of a nerve (in nine of 38 patients). The incidence of nerve damage from PNS therapy itself is unknown and believed to be rare. To avoid nerve damage, practitioners should maintain excellent knowledge of relevant anatomy and watch for patient neuralgia and radicular pain in the postoperative period. Treatment of suspected nerve injury may include steroid protocol, anticonvulsants, and referral for neurologic consult.

Allergic events in PNS procedures can range from mild topical reactions to full anaphylaxis. Allergic events generally surround the use of preoperative skin preparations, antibiotics, local anesthetics, latex, and sedative medications (e.g., midazolam). Rarely, patients have reported allergic events to the PNS equipment itself, although this seems to be a delayed reaction.

Taking a thorough patient history is beneficial in determining whether the patient is allergic to any of the agents used in PNS therapies. Because the patient may be unaware of any allergies surrounding these products, the physician should remain vigilant for development of allergic sequelae during PNS. For example, local anesthetics are common elicitors of adverse reactions with clinical symptoms such as anaphylaxis with tachycardia; hypotension; and subjective feelings of weakness, heat, or vertigo.⁷ Furthermore, during general anesthesia or sedation, anaphylactic response to IV hypnotics and other drugs can occur; cardiovascular collapse and bronchospasm are frequent in immunoglobulin E–dependent reactions.⁸ In addition, latex can produce allergic reactions as serious as anaphylaxis.⁹

Although the incidence of allergic or toxic reactions to skin preparations is unusual, practitioners should remain aware that iodine tincture and chlorhexidine can produce adverse outcomes in some patients. It is advisable to take a thorough patient history to avoid cutaneous manifestations, particularly in patients with skin sensitivity or other drug allergies. Iodine is associated with adverse effects ranging from minor skin irritation to anaphylaxis, with symptoms occurring within minutes and up to 8 hours after contact.¹⁰ In addition, the incidence of contact dermatitis to chlorhexidine in atopic patients is approximately 2.5% to 5.4%, and acute hypersensitivity reactions to chlorhexidine are often not recognized and therefore may be underreported.¹¹

Skin preparations are a topic of concern not only because of their allergic potential but also because of choice of agent (e.g., iodine tincture vs. chlorhexidine). According to a 2010 study published in the New England Journal of Medicine,¹² preoperative cleansing of the patient’s skin with chlorhexidine–alcohol was superior to cleansing with povidone–iodine for preventing surgical site infection (SSI) after clean-contaminated surgery. Chlorhexidine–alcohol was significantly more protective than povidone–iodine against both superficial incisional infections (4.2% vs. 8.6%; P = 0.008) and deep incisional infections (1% vs. 3%, P = .05), although it was not effective against organ space infections (4.4% vs. 4.5%). Furthermore, according to Barenfanger et al,¹³ in choosing a skin preparation for surgical site antisepsis in PNS, it should be noted that although iodine tincture has been called the “gold standard” in preoperative skin preparation, it does not provide statistically greater utility than chlorhexidine in terms of contamination rates, and chlorhexidine may be safer, less expensive, and preferred by staff members. Furthermore, iodine tincture has the disadvantage of being toxic when used repeatedly, but toxicity or sensitization caused by chlorhexidine is very uncommon. However, Barenfanger et al¹³ found that the average contamination rate with chlorhexidine was found to be slightly greater than with iodine (3.13%, or 186 contaminants in 5936 cultures, vs. 2.72%, or 158 contaminants in 5802 cultures).

Numerous randomized, controlled trials in the literature underscore the benefits of giving prophylactic antibiotics to the patient immediately before surgical procedures such as PNS to inhibit development of infection, although the risk of allergic reaction to antibiotics exists. Classen et al¹⁴ prospectively monitored the timing of antibiotic prophylaxis and development of surgical wound infections in 2847 patients undergoing surgical procedures. Among patients who received antibiotics up to 24 hours before surgery, 2 hours before surgery, 3 hours after surgery, and more than 3 hours after surgery, those who received antibiotics 2 hours before surgery had the lowest rates of subsequent surgical wound infections. Furthermore, according to a surgeon’s perspective by Nichols,¹⁵ it is generally recommended in elective clean surgical procedures using a foreign body and in clean-contaminated procedures that IV antibiotics should be administered in the operative suite immediately before incision.

Although innumerable clinical trials demonstrate the efficacy of preoperative administration of antibiotics against subsequent infection, physicians should remain mindful of the possibility of unexpected antibiotic allergy in these patients. Although allergic reactions to antibiotics account for only a small proportion of reported adverse drug reactions and estimates of their prevalence vary widely, they are associated with substantial morbidity and mortality and increased health care costs.¹⁶

Although infectious complications of PNS and PNfS techniques have generally been associated with less morbidity and mortality as compared to spinal cord stimulation, serious infectious complications have been described. In an unpublished case at the Cleveland clinic, a patient underwent PNfS for somatic abdominal pain, placing the lead in transversus abdominal plane using US guidance. Six weeks later the patient presented with an acute abdomen and sepsis secondary to erosion of the leads into the peritoneal cavity, with subsequent death from septic complications.