The Physiology of Chronic Pain

The Physiology of Chronic Pain

The Physiology of Chronic Pain

It is estimated that chronic pain is one of the most common reasons adults are seeking medical care. Approximately 50 million adults in America are suffering from chronic pain in the United States. 19.6 million adults are experiencing high-impact chronic pain that is causing even more of an interruption in their quality of life. Chronic pain can be debilitating for some and affect mental health just as much as physical health. There is a shift in the body’s anatomy and physiology when chronic pain is present. 

Defining Chronic Pain

There are different types of pain and diagnosing someone’s pain correctly is a critical part of providing them with the best treatment. Chronic pain is pain that lasts for 3-6 months or longer. This type of pain can present with a variety of symptoms including: 

  • Burning
  • Aching
  • Sharp 
  • Limited mobility
  • Joint stiffness 
  • Fatigue
  • Anxiety 
  • Depression 
  • Tingling or numbness 

There are multiple treatment options to aid in the reduction of these types of symptoms. 

The Development of Chronic Pain

There are two types of physiological pain, nociceptive and neuropathic. Nociceptive pain occurs as a result of tissue damage and/or inflammation caused by arthritis, cancer, or physical trauma. When nociceptors, the sensory receptors for pain, are activated, they are transmitted to the spinal corn. In the spinal cord, these incoming signals are modulated and transmitted by neurotransmitters and passed on to the brain stem. The brain stem acts as a mediator of these pain signals. Essentially, nociceptive pain is the body’s reaction to painful stimuli. 

Neuropathic pain is pain that arises as a direct result of lesions or dysfunctions within the nervous system. Three of the most common conditions that are associated with neuropathic pain are diabetic peripheral neuropathy, postherpetic neuralgia, and cancer. This type of pain is usually more severe than nociceptive pain and presents as more of a burning or tingling sensation. 

Neuropathic pain and nociceptive pain can coexist, but not every patient that experiences chronic pain experiences both types of pain. Many patients may not know which type of pain is the cause of their discomfort. Nociceptive pain is a reaction to painful stimuli. Neuropathic pain is a malfunction within the nervous system. This is where the physiological difference lies in how the body responds to pain. 

How it Affects Mental Health

Studies show there is a strong correlation between chronic pain and mental health. One study of patients admitted to a comprehensive pain center shows that half of the men and two-thirds of the women were suffering from affective disorders in addition to the chronic pain. 59% of the men and 66% of the women presented with anxiety disorders. 

For some, the pain precedes the mental health disorders, for others, they may be prone to experience mental illnesses and a traumatic event that causes chronic pain brings those struggles to light. Depression is one form of mental illness that is closely linked to chronic pain. Depression has been identified as a type of somatization, the expression of emotional feelings through physical, bodily complaints. This type of somatization occurs as a subconscious response to underlying emotions.  There are alterations in the neurotransmitters serotonin and norepinephrine in patients with depression. These alterations have been proven to play critical roles in how the body feels and responds to pain.  Some individuals have considered chronic pain to be the most common form of somatization in American society.

Chronic pain can present itself in different forms and have different causes. From nociceptive pain to neuropathic pain, and even imbalances in neurotransmitters as a result of mental illnesses like depression can be linked to chronic pain in patients. Seeking proper treatment and identifying the root cause of pain will allow patients to experience the most effective forms of treatment and begin rebuilding their quality of life.