One hundred million American adults live in chronic pain, according to a 2011 report from the prestigious Institute of Medicine, an arm of the National Academy of Sciences.

Usually defined as pain lasting three to six months or more, chronic pain is vastly different from short-term, acute pain. It can transform life. In some cases it can literally shrink the brain. It can turn the nervous system into a runaway, self-sustaining nightmare in which the body may no longer even need stimulation from the outside world to produce pain – revved-up nerves doing it all by themselves.

In a way, chronic pain is a kind of perverse learning – connections among pain nerves actually get stronger and stronger. Eventually, even the slightest touch, like a feather on the skin, can feel like the scalding burn of a blowtorch, a condition technically called allodynia. This is not simply acute pain that lasts too long. It is the nervous system run amok – biologically, psychologically and socially, a whole new problem.

Chronic pain, of course, is not just a biological, psychological, and social burden. It is an enormous economic burden as well, by some accounts, the leading reason that patients go to doctors. It costs the country more than cancer, heart disease, and diabetes combined and accounts for 42 percent of all visits to hospital emergency rooms.

 

WHAT IS PAIN?

The official definition of pain: “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”

In many pain syndromes, an obvious, physical injury or cause of chronic pain can never be found, a puzzle that is a source of enormous frustration to people with pain and doctors alike.

Chronic pain is now seen as a biopsychosocial phenomenon, not just a linear response to an unpleasant stimulus, but an ever-changing, almost living thing, an intricately interwoven tapestry that includes not just physical sensations but also our emotional responses to pain and our emotional responses to other people’s emotional responses to our pain.

 

THE FOUR TYPES OF PAIN

Chronic pain can be divided in four types – nociceptive, inflammatory, dysfunctional and neuropathic, which describes different ways of understanding how pain signals travel in the nervous system. Sometimes, chronic pain can be a combination of these types.

Nociceptive pain is that instant, intense reaction you get when you hit your thumb hard with a hammer or cut your finger with a knife. Nociceptive pain is basically “good”, or adaptive, because is serves an important, biological purpose: It alerts you to danger and lets you know about your now-damaged tissue, which motivates you to be gentle with the damaged area until it heals. When your thumb heals, it’s all over – pain nerves quiet down and you forget all about it.

Inflammatory pain is a bit different. Once that sore thumb swells up and gets all red, even the slightest touch can hurt. Inflammatory pain persists as long as the tissue remains damaged and swollen. In a sense, inflammatory pain, like nociceptive pain, is somewhat “good”, or adaptive, in the sense that inflammation does good things, including the secretion of natural chemicals called cytokines that act to promote healing.

Dysfunctional pain as its name implies serves no purpose at all – it’s totally useless, maladaptive, and devoid of any redeeming virtues. In dysfunctional pain conditions like fibromyalgia, irritable bowel syndrome, and some types of headache, pain can be triggered without any external pain stimulus at all, at least as far as scientists can tell. With dysfunctional pain, there’s no damage to the nervous system itself and no inflammation.

Neuropathic pain is the most complicated of the pain problems. Neuropathic pain is caused by damage to the nervous system itself. Neuropathic pain attacks the nervous system by altering the way nerves function – an insult to the very system that is supposed to deal with pain. This, of course, makes treatment extraordinarily tricky. While nociceptive pain, that simple kind, is all over when it’s over, neuropathic pain goes on and on, long after the initial trigger, if there was an obvious one, is history.

Neuropathic pain occurs in conjunction with many diseases and different types of damage to the nervous system, including trauma to nerves (as in surgery), pressure on nerves (as from a herniated disc in the neck or back), injury from toxic chemicals landing on nerves (as in chemotherapy), infection from certain viruses like herpes zoster, and so on.

 

THE TREATMENT OF CHRONIC PAIN

 I – Non-pharmacological treatments

• Physical Therapy
• Electrical Stimulation (TENS, spinal stimulation)
• Massage
• Acupuncture
• Reiki
• Yoga
• Chiropractics
• Injections (joints, spine, nerve blocks, radiofrequency ablation, botox, trigger points)
• Surgery

II – Pharmacological treatments

• Vitamins and supplements
• NSAIDS
• Muscle relaxers
• Topical analgesics (patches, ointments)
• Steroids
• Opioids
• Intra-thecal pump infusion

III – Miscellaneous

• Deep relaxation techniques
• Meditation
• Hypnosis
• Biofeedback
• Neurofeedback

 

Above are excerpts from the book A Nation in Pain by Judy Foreman, Oxford University Press, 2014