By: Dr. Daniel Chillianis, PT, DPT
Pain is quite paradoxical in the sense that it is a universal experience that almost all humans experience at some point across a lifespan; however, your pain is unique, personal and intimate to the individual experiencing it due to the biopsychosocial factors which mold our response to the sensation.
Overview:
In its truest physiological sense pain is an advantageous evolutionary response to perceived danger or threat that serves as an “alarm system” to protect survival.
Nociception is the technical term for the process by which our nervous system detects a harmful stimuli (ie. Excessive Pressure, Extreme Temperatures or Tissue Damage)
Pain vs. Nociception:
Although related Pain and Nociception ARE NOT THE SAME THING and here is why!
Nociception:
Our nervous systems detection of a potentially harmful stimulus
Nociception is detected by receptor cells which are found in skin/muscles/joints and information is relayed via spinal nerves which coordinate a response with our motor neurons to protect our body
Nociception does not require conscious thought!
Example: Touching a Hot Stove
When you touch a hot stove your body reflexively removes your hand from the hot surface.
We are not required to consciously assess the temperature of the stove and devise a plan on how to remove our hand, it just happens involuntarily.
Pain:
This is where it gets a little gray and messy
Pain is a diffuse neurological process informed by both PNS and CNS. CNS pain processing sites include somatosensory cortex, motor cortex, prefrontal cortex, insular cortex, anterior cingulate cortex, amygdala, hippocampus, thalamus, basal ganglia, brain stem, midbrain, spinal cord
The Limbic System (our emotional nervous system) plays a CRITICAL ROLE in pain demonstrating that pain is NOT ALWAYS Physical but is ALWAYS EMOTIONAL.
Biopsychosocial Experience:
- ALL PAIN IS BIOPSYCHOSOCIAL and these three domains interplay to produce and reduce pain sensation
Bio (Biological): age, genetics, tissue damage, system dysfunction, anatomical and biomechanical issues, inflammation, diet, sleep, etc.
Psycho (Psychologic): thoughts, beliefs, memories, appraisals and evaluative processes, executive and attentional processes, emotions (stress, anxiety, depression, anger, etc), trauma, coping behaviors, etc.
Social: socioeconomic status, access to care, race, culture, ethnicity, family factors, home environment, media, society, context, environmental factors, etc.
Effective treatment requires a multidisciplinary approach targeting brain and body, combining medicine, psychology, physical therapy, occupational therapy, biofeedback, and other modalities.
Biomedical and psychosocial interventions must be prioritized EQUALLY.
Summary:
Pain is born from sensory information from the body + nociceptors travel from spinal cord up to brain followed by conscious recognition of potential danger.
Sensory signals are modulated by cognitive, emotional and contextual inputs
Brain incorporates input from nociceptors, five senses, thoughts, memories, emotions, environment, and other biopsychosocial inputs to determine whether or not to make pain, and how much.
Multiple CNS sites work together to reach a conclusion about what’s happening and how to respond and if there’s any reason to believe protection is required, THE BRAIN WILL MAKE PAIN! Brain then sends messages back down to the body via spinal cord, informing subsequent decisions and actions.
Valence matters: Negative thoughts and emotions (e.g. anxiety, stress, sadness, anger) amplify pain. Positive thoughts and emotions (e.g. happiness, gratitude, relaxation) attenuate it.
Context matters: injuries sustained in negative or stressful circumstances feel worse than those that occur in relaxing, positive contexts. Pleasurable situations and distractions attenuate pain, while attending to and worrying about pain amplifies it. The same sensory input in one context may be benign or pleasurable (e.g., a playful kick) and painful in another (e.g., the same kick sustained during a fight)
Pain is a guesstimate, the brain’s best guess based on all available information. Pain is not an accurate indicator of whether the body is actually damaged, nor how much.
References:
Thompson, K.; Johnson, M.I.; Milligan, J.; Briggs, M. Twenty-five years of pain education research-what have we learned? Findings from a comprehensive scoping review of research into pre-registration pain education for health professionals. Pain 2018, 159, 2146–2158.
Wade DT, Halligan PW. The biopsychosocial model of illness: a model whose time has come. Clin Rehabil. 2017 Aug 1;31(8):995–1004.
Melzack R & Wall PD. Pain mechanisms: A new theory: A gate control system modulates sensory input from the skin before it evokes pain perception and response. Pain Forum. 1996 Mar 1;5(1):3–11.Melzack R. From the Gate to the Neuromatrix. Pain. 1999;82:S121–6.
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