A study has found that ketamine may be more helpful in preventing postoperative pain among a subset of patients with a higher tendency toward central sensitization as measured by TSP (temporal summation of pain). In a small group of patients with a higher TSP score before surgery, those who received ketamine reported lower pain after surgery than those who received a placebo.
Central sensitization (CS), a hypersensitivity toward stimuli that are not typically painful, is due to a heightened reactivity of the nervous system and may occur in some patients after surgery, slowing the recovery process and leading to chronic pain. The degree of CS is frequently measured in patients before surgery using a brief standardized pain test. This test can be used before surgery to measure how a patient responds to a painful stimulus repeated over time. This response, known as temporal summation of pain (TSP), varies among patients, and a higher TSP is associated with worse pain after surgery.
Ketamine, frequently used for pain relief during surgery, can block receptors that activate central sensitization. The study examined whether ketamine reduced pain in women after breast surgery and whether ketamine was more effective at pain reduction in those with a higher tendency toward CS, measured as high TSP.
In this study conducted at Brigham and Women’s Hospital, Harvard Medical School, in Boston, MA, women underwent a brief testing of their tendency toward central centralization using mechanical pinprick stimuli before surgery, providing a TSP score. Patients received either ketamine or placebo during surgery. Two weeks after surgery, women reported their pain severity using a standardized Brief Pain Inventory questionnaire. In addition, researchers analyzed whether the patients’ TSP score before surgery influenced the efficacy of ketamine in reducing their pain after surgery.
There was no difference in pain after surgery between women who received ketamine versus placebo overall. However, among the smaller group of women with a higher TSP score before surgery, those who received ketamine reported lower pain after surgery than those who received placebo. In contrast, there was no difference in pain between women who received ketamine versus placebo among those with a lower TSP score.
“We hope this research will promote the personalization of pain treatments,” said investigator Sheila R. Gokul, lead author of the abstract “RCT of Ketamine in Mastectomy: Differential Analgesic Efficacy Based on a QST-Based Measure of Preoperative Central Sensitization.” The abstract was chosen for a Resident/Fellow Travel Award at the 48th Annual Regional Anesthesiology and Acute Pain Medicine Meeting. Dr. Gokul will present the findings at a session on Saturday, April 22, at 3:30 pm, at The Diplomat Beach Resort in Hollywood, FL. Coauthors are Drs. Jenna M. Wilson, K. Mikayla Flowers, Carin Colebaugh, Angelina Franqueiro, Jingui He, Robert R. Edwards, & Kristin L. Schreiber.
ASRA Pain Medicine is a membership society of more than 5,000 healthcare professionals devoted to advancing evidence-based practice of pain medicine across the pain continuum, from acute pain to chronic pain. Our mission is to advance the science and practice of regional anesthesia and pain medicine to improve patient outcomes through research, education, and advocacy. Our vision is to relieve the global burden of pain. We are committed to integrity, innovation, inclusiveness, service, compassion, and wellness. Learn more at www.asra.com.
