Nerve Stimulation In Postoperative Pain Management After Colorectal Surgery.

With the adoption of enhanced recovery pathways after surgery, colorectal surgeons are already attuned to reducing the use of opioids in the postoperative recovery period. Recent attention to the opioid addiction epidemic in the United States has brought another round of investigation into pain management in the postoperative setting. Neurostimulation is a well-developed intervention for the management of pain syndromes such as low back pain and headaches. However, utilization in the acute pain setting is quite limited, and effective techniques have not been reported. The cumbersome and invasive nature of percutaneous lead placement targeting short-term pain control likely presents challenges to the discovery of efficacious techniques. Transcutaneous neuromodulation is a simpler approach, but is also understudied. Few reports are noted in the literature primarily related to orthopedic surgery. One study evaluated this technique for posthemorrhoidectomy pain. Acupuncture, another nonpharmacologic modality used for pain control, is an established adjunct in patients who have chronic pain, with evidence of effectiveness. Interestingly, acupuncture has been investigated in a variety of postoperative settings, but it is far from widely utilized. In the study by Blank et al, the authors report the results of their randomized trial that tested whether a newly devised battery-powered neurostimulation device applied to the ear for 4 days postoperatively would reduce total opioid consumption compared to a sham device. The NSS2-BRIDGE (Innovative Health Solutions, Versailles, IN) device, illustrated in the published article, proposes to stimulate cranial nerves V, VII, XI, and X. Several secondary outcomes were studied. The study was small, with 52 patients randomly selected, and did not find significant differences in the primary or secondary outcomes. Prior supporting research for this study included animal studies on pain perception and a single randomized sham-controlled trial in adolescents with functional GI pain, which showed a benefit. The literature on auricular neurostimulation in a postoperative setting is sparse, with 1 study in patients undergoing cesarean delivery using a percutaneous approach applied for 48 hours postoperatively. This study, also a randomized trial, found a benefit for percutaneous auricular stimulation. Why would stimulation of the ear help with postoperative abdominal pain? Blank et al suggest an effect on the autonomic nervous system including interaction with the vagus nerve. Auricular neurostimulation is conceptually similar to auricular acupuncture, which has been recently evaluated in the military as part of a technique known as “battlefield acupuncture. ” A few clinical studies support a benefit for pain. Battlefield acupuncture uses needles shaped like conical darts placed in 5 locations on the ear and left to stay in the patient for 3 to 4 days. The mechanism of action for acupuncture and neurostimulation in pain management have different theoretical underpinnings but may be related. Blank et al use a randomized controlled trial design for their study. Although randomized trials provide the highest level of evidence to test a focused clinical question, the investigators’ assessment of auricular neurostimulation is insufficiently supported by primary data. Because we have no baseline data from other studies, we are not able to gauge whether the study was designed well enough to be conclusive. Because the intervention Funding/Support: None reported.