This blog was written by Carolyn McManus, PT, MS, MA, who will be presenting at the APTA's Virtual NEXT conference in North Carolina. Carolyn is instructing a new course with Mindfulness-Based Biopsychosocial Approach to Chronic Pain. This course will be offered November 15-16, 2014 in Seattle, WA.
We all know a highly stressed patient will have a more complicated and prolonged healing process than a non-stressed patient. Recent research is finally illuminating possible mechanisms causing the amplification of pain by stress. For example, stress has been shown to enhance muscle nociceptor activity in rats. (1) In this study, water avoidance stress produced mechanical hyperalgesia in skeletal muscle and a significant decrease in the mechanical threshold of muscle nocicpetors, a nearly two fold increase in the number of action potentials produced by a fixed intensity stimulus and an increase in conduction velocity from 1.25 m/s to 2.09 m/s! Researchers suggest these effects are due, at least in part, to catecholamines and glucocorticoids acting on adrenergic and glucocorticoid receptors on sensory neurons.
I always talk about this study with my patients who have persistent pain. It helps them understand that pain can escalate, not because of tissue damage, but because of the effects of stress hormones on their nerves. They understand that if they persist in escalating their stress reaction they will limit their healing potential. There is more research on this topic and strategies to help patients self-regulate their stress reaction that I look forward to discussing in my upcoming course in November.