After surgery, pain is expected and often subsides within a few weeks. But for around 20% of patients, persistent pain may continue for months or even years after a procedure, impacting quality of life and putting patients at risk for opioid overuse. Symptoms vary widely in severity and in the type of pain experienced, making chronic pain difficult to treat.
Researchers at Washington University School of Medicine in St. Louis have received nearly $5 million from the National Institute of Neurological Disorders and Stroke of the National Institutes of Health (NIH) to support research aimed at identifying the factors responsible for differences in chronic post-surgical pain.
We don’t fully understand what causes pain symptoms to persist in some patients but not in others recovering from surgery, or what contributes to the variable symptoms among those who develop chronic pain. Such knowledge may allow us to develop personalized risk-assessment, pain prevention and management tools to help patients make more informed decisions, lower their risk of long-term opioid use and improve quality of life.”
Simon Haroutounian, PhD, professor of anesthesiology at WashU Medicine
Tools to predict, prevent and treat chronic pain after surgery are lacking, making it difficult for patients to make crucial healthcare decisions. For example, patients with a family history and genetic risk of breast cancer may choose close monitoring over a prophylactic double mastectomy – a procedure that carries a higher- than-average risk of chronic post-surgical pain – if they know they are at increased individual risk for developing long-term, debilitating pain. Conversely, the same patient might opt for surgery if they could be equipped with a personalized prevention or pain management plan.
But understanding the complex physiological process of pain is challenging. Pain involves more than just an unpleasant sensation, explained Haroutounian. The pain experience is caused by interactions between components of the injured tissues, peripheral and central nervous systems, the immune system and the person’s emotional and cognitive response to the pain itself. It is not uncommon for two patients with chronic pain after the same surgery to describe vastly different pain experiences. Pain symptoms can range from mild to severe, may worsen or improve with activity, and can feel sharp, dull, burning or throbbing, among other sensations.
The multidisciplinary research team includes WashU researchers Meaghan Creed, PhD, an associate professor of anesthesiology, Pratik Sinha, MBChB, PhD, an assistant professor of anesthesiology, and Chenyang Lu, PhD, the Fullgraf Professor of Computer Science & Engineering. The team also will collaborate with Thomas Rodebaugh, PhD, a professor of psychology and neuroscience at the University of North Carolina at Chapel Hill, and Andrew Shepherd, PhD, an assistant professor of symptom research at the University of Texas MD Anderson Cancer Center.
The team will examine more than 300 surgery patients to understand genetic, molecular, neuro-immune and behavioral patterns that explain the variability in patients’ post-surgical pain. They will use machine learning approaches to identify patient subgroups with common characteristics and contributors to pain. By developing animal models that parallel the unique profiles of each subgroup, the researchers aim to identify the processes that contribute to the pain, to help develop targeted therapeutics.
“We have put together a team that spans different disciplines,” said Haroutounian, also the division chief of clinical pain research at the Washington University Pain Center. “By integrating expertise in pain biology, pain management, critical care, psychology, immunology, computer science and engineering, we seek a comprehensive understanding of chronic pain that occurs after surgery. Pooling our resources and knowledge allows us to take a multi-dimensional approach to studying the mechanisms of such pain and to lay the foundation for developing effective personalized solutions.”
