1. 2019;22;479-488Transition from Acute to Chronic Pain: Evaluating Risk for Chronic Postsurgical Pain
   Narrative Review
   Gabriel Fregoso, MD, Annie Wang, MD, Kelly Tseng, MD, and Jingping Wang, MD, PhD.

BACKGROUND: The pathophysiology of pain involves complex nervous system interactions after initial noxious stimuli. When stimuli persist, biochemical and structural changes occur in the nociceptive pathways of the central and peripheral nervous systems, leading to pain sensitization. Peripheral and central sensitization are key in the transition from acute to chronic pain. This development of chronic pain is particularly common following various surgical procedures, with many postsurgical patients experiencing persistent pain for significant periods. Chronic pain is a common and severe complication of surgery, and preventing its development is tantamount in improving patient outcomes.

OBJECTIVES: To understand underlying pathophysiology of chronic postsurgical pain (CPSP) and the underlying risk factors predisposing the transition from acute to CPSP. To review our ability to identify patients at highest risk for the development CPSP. To identify evidence-based multimodal approaches that can aid in the prevention of CPSP.

STUDY DESIGN: Narrative review of peer-reviewed literature.

SETTING: Inpatient surgical centers.

METHODS: Medline and Cochrane databases were reviewed to identify publications relevant to CPSP pathophysiology, risk factors, predictive models, and prevention. Publications were selected based on author expertise to summarize our current understanding of CPSP.

RESULTS: This review presents our current understanding of CPSP in the following domains: underlying pathophysiology, predisposing risk factors, predictive models of CPSP, and preventative strategies. Each section provides a structured review of key evidence base to understand the complex topic of CPSP.

LIMITATIONS: This narrative review is a nonsystematic review of relevant publications aimed at presenting succinct overview of CPSP.

CONCLUSIONS: The incidence of CPSP can potentially be reduced through early identification of perioperative, genetic, physiologic, and psychologic factors. Models predicting the development of CPSP continue to improve and may help focus preventative efforts in patients at highest risk. There is a growing body of evidence supporting the use of multimodal analgesia and anesthetic techniques in the reducing rates of CPSP development.

KEY WORDS: Acute pain, chronic postsurgical pain, pain sensitization, chronic pain prevention, regional anesthesia, pain adjuncts, neuraxial anesthesia, chronic pain risk factors