Intramuscular Electrical Stimulation Relieves Pain After Open Pancreaticoduodenectomy

By Will Boggs MD

August 12, 2020

NEW YORK (Reuters Health) - Intramuscular electrical stimulation can help relieve pain following open pancreaticoduodenectomy, according to results from a randomized clinical trial.

"Needle electrical twitch obtaining intramuscular stimulation (NETOIMS) has been used to alleviate muscular pain from muscle strain or myofascial pain syndrome," said Dr. Joon Seong Park of Gangnam Severance Hospital, Yonsei University, in Seoul, South Korea.

"Thus, we had expected that it would reduce postoperative muscle-originating pain from the planning stage of this research, so the pain score reduction is not a surprising result for us," he told Reuters Health by email. "However, it is noteworthy that the recovery times of peak cough flow and gait speed also have been drastically reduced in NETOIMS group."

NETOIMS targets the deep motor endplate zones of skeletal muscles and results in muscle relaxation immediately following the electrically elicited muscle contractions. No previous study has investigated the effects of NETOIMS on postoperative pain after open abdominal surgery.

Dr. Park and colleagues evaluated the clinical effects of NETOIMS on postoperative pain relief, functional recovery of gait speed, and pulmonary complication reduction in 44 patients with pancreaticobiliary tumors who underwent pylorus-preserving pancreaticoduodenectomy (PPPD).

Immediately following abdominal closure, NETOIMS was performed at 14 stimulation points in the bilateral rectus abdominis muscles. Each point was stimulated with 1 Hz for 10 seconds each.

The pain visual analog score (VAS, scored from 0 = none to 10 = worst) on postoperative day 3, the primary endpoint, was significantly lower in the NETOIMS group than in the control group (3.22 vs. 4.05), the researchers report in the Journal of the American College of Surgeons.

The mean time taken for the pain score to drop to 2 was 12.4 days for the NETOIMS group versus 15.0 days for the control group. Pain scores returned to preoperative levels in both groups by postoperative day 28.

Among secondary outcomes, the time taken for the mean gait speed to be at least 100% of the preoperative level was 20.7 days for the NETOIMS group and 29.0 days for the control group.

Peak cough flow (the maximum air flow generated during a cough) decreased after surgery in both groups and recovered to preoperative levels by postoperative day 28. The improvement in peak flow from postoperative day 2 to postoperative day 7 was significantly larger in the NETOIMS group than in the control group (25.33% vs. 17.13%).

There were no adverse events related to the intervention and no serious adverse events during the study.

"Even if it is more cumbersome than medication, we would like to increase the interest in minimally invasive therapy such as NETOIMS, which can target deep muscle fibers while eliminating the risk of systemic side effects caused by medication," Dr. Park said.

"We are preparing a next-step research for actual clinical help for patients' better quality of life," he said. "We hope to be able to share the good news again."

Dr. Thomas M. Hemmerling of McGill University, in Montreal, Canada, who has researched various treatments for postoperative pain, told Reuters Health by email, "My personal preference in terms of balance of analgesic efficacy and benefit-risk profile is administration of transversus abdominal blocks using local anesthesia, either as a single-shot technique or continuous administration after catheter insertion. NETOIMS targets - electrically - a similar area stimulation of the bilateral rectus abdominis muscles, equally under ultrasound guidance."

"Obviously, we are just at the beginning: future research should focus on the different modes of application and if they make a difference on the postoperative pain," he said.

"If future studies confirm the efficacy of this method, then it could be part of the multimodal perioperative pain strategy," Dr. Hemmerling said. "One could imagine combining a multimodal, preferably opioid-free, drug therapy with pain blocks based on single shot or continuous administration of local anesthesia near the wound, with NETOIMS."

SOURCE: Journal of the American College of Surgeons, online July 2, 2020