Pain is an unpleasant sensation and emotional experience that links to tissue damage. It allows the body to react and prevent further tissue damage.

People feel pain when a signal travels through nerve fibers to the brain for interpretation. The experience of pain is different for every person, and there are various ways to feel and describe pain. This variation can, in some cases, make it challenging to define and treat pain.

Pain can be short- or long-term and stay in one place or spread around the body.

In this article, we look at the different causes and types of pain, different ways to diagnose it, and how to manage the sensation.

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Pain can be chronic or acute and take have a variety of forms and severities.

People feel pain when specific nerves called nociceptors detect tissue damage and transmit information about the damage along the spinal cord to the brain.

For example, touching a hot surface will send a message through a reflex arc in the spinal cord and cause an immediate contraction of the muscles. This contraction will pull the hand away from the hot surface, limiting further damage.

This reflex occurs so fast that the message has not even reached the brain. However, the pain message does continue to the brain. Once it arrives, it will cause an individual to feel an unpleasant sensation — pain.

The brain’s interpretation of these signals and the efficiency of the communication channel between the nociceptors and the brain dictate how an individual experiences pain.

The brain may also release feel-good chemicals, such as dopamine, to try to counter the unpleasant effects of pain.

In 2011, researchers estimated that pain costs the United States between $560 billion and $635 billion each year in treatment costs, lost wages, and missed days of work.

Pain can be either acute or chronic.

Acute pain

This type of pain is generally intense and short-lived. It is how the body alerts a person to an injury or localized tissue damage. Treating the underlying injury usually resolves acute pain.

Acute pain triggers the body’s fight-or-flight mechanism, often resulting in faster heartbeats and breathing rates.

There are different types of acute pain:

  • Somatic pain: A person feels this superficial pain on the skin or the soft tissues just below the skin.
  • Visceral pain: This pain originates in the internal organs and the linings of cavities in the body.
  • Referred pain: A person feels referred pain at a location other than the source of tissue damage. For example, people often experience shoulder pain during a heart attack.

Chronic pain

This type of pain lasts far longer than acute pain, and there is often no cure. Chronic pain can be mild or severe. It can also be either continuous, such as in arthritis, or intermittent, as with migraines. Intermittent pain occurs on repeated occasions but stops in between flares.

The fight-or-flight reactions eventually stop in people with chronic pain as the sympathetic nervous system that triggers these reactions adapts to the pain stimulus.

If enough cases of acute pain occur, they can create a buildup of electrical signals in the central nervous system (CNS) that overstimulate the nerve fibers.

This effect is known as “windup,” with this term comparing the buildup of electrical signals to a windup toy. Winding a toy with more intensity leads to the toy running faster for longer. Chronic pain works in the same way, which is why a person may feel pain long after the event that first caused it.

Describing pain

There are other, more specialized ways of describing pain.

These include:

  • Neuropathic pain: This pain occurs following injury to the peripheral nerves that connect the brain and spinal cord to the rest of the body. It can feel like electric shocks or cause tenderness, numbness, tingling, or discomfort.
  • Phantom pain: Phantom pain occurs after the amputation of a limb and refers to painful sensations that feel as though they are coming from the missing limb.
  • Central pain: This type of pain often occurs due to infarction, abscesses, tumors, degeneration, or bleeding in the brain and spinal cord. Central pain is ongoing, and it can range from mild to extremely painful. People with central pain report burning, aching, and pressing sensations.

Knowing how to describe pain can help a doctor provide a more specific diagnosis.

An individual’s subjective description of the pain will help the doctor make a diagnosis. There is no objective scale for identifying the type of pain, so the doctor will take a pain history.

They will ask the individual to describe:

  • the character of all pains, such as burning, stinging, or stabbing
  • the site, quality, and radiation of pain, meaning where a person feels the pain, what it feels like, and how far it seems to have spread
  • which factors aggravate and relieve the pain
  • the times at which pain occurs throughout the day
  • its effect on the person’s daily function and mood
  • the person’s understanding of their pain

Several systems can identify and grade pain. However, the most important factor in getting an accurate diagnosis is for the individual and the doctor to communicate as clearly as possible.

Measuring pain

Some of the pain measures that doctors use are:

  • Numerical rating scales: These measure pain on a scale of 0–10, where 0 means no pain at all, and 10 represents the worst pain imaginable. It is useful for gauging how pain levels change in response to treatment or a deteriorating condition.
  • Verbal descriptor scale: This scale may help a doctor measure pain levels in children with cognitive impairments, older adults, autistic people, and those with dyslexia. Instead of using numbers, the doctor asks different descriptive questions to narrow down the type of pain.
  • Faces scale: The doctor shows the person in pain a range of expressive faces, ranging from distressed to happy. Doctors mainly use this scale with children. The method has also shown effective responses in autistic people.
  • Brief pain inventory: This more detailed written questionnaire can help doctors gauge the effect of a person’s pain on their mood, activity, sleep patterns, and interpersonal relationships. It also charts the timeline of the pain to detect any patterns.
  • McGill Pain Questionnaire (MPQ): The MPQ encourages people to choose words from 20 word groups to get an in-depth understanding of how the pain feels. Group 6, for example, is “tugging, pulling, wrenching,” while group 9 is “dull, sore, hurting, aching, heavy.”

Other indicators of pain

When people with cognitive impairments cannot accurately describe their pain, there can still be clear indicators. These include:

  • restlessness
  • crying
  • moaning and groaning
  • grimacing
  • resistance to care
  • reduced social interactions
  • increased wandering
  • not eating
  • sleeping problems

The doctor will either treat the underlying problem, if it is treatable, or prescribe pain-relieving treatment to manage the pain.

Doctors will treat different types of pain in different ways. A treatment that is effective against one type of pain may not relieve another.

Acute pain treatment

Treating acute pain often involves taking medication.

Nonsteroidal anti-inflammatories (NSAIDs)

These are a type of analgesic, or pain reliever, that can reduce pain and help a person regain daily function. They are available over the counter (OTC) or on prescription at a range of strengths. They are suitable for minor acute pains, such as headaches, light sprains, and backaches.

NSAIDs can relieve localized inflammation and pain that is due to swelling. These drugs may have side effects relating to the digestive system, including bleeding. Therefore, a doctor will monitor a person taking a high dosage.

It is always important to read the packaging to find out what is in an analgesic before using it and to check the maximum dosage. People should never exceed the recommended dosage.

Opioids

Doctors prescribe these drugs for the most extreme acute pains, such as those that result from surgery, burns, cancer, and bone fractures. Opioids are highly addictive, cause withdrawal symptoms, and lose effectiveness over time. They require a prescription.

In situations involving severe trauma and pain, the doctor will carefully manage and administer the dosage, gradually reducing the amount to minimize withdrawal symptoms.

People should discuss all medication options carefully with a doctor and disclose any health conditions and current medications. Opioids may significantly affect the progression of several chronic diseases, including:

  • chronic obstructive pulmonary disorder (COPD)
  • kidney disease
  • liver problems
  • previous drug use disorder
  • dementia

A doctor can often identify and treat an underlying disorder. For example, if an infection is causing a sore throat, antibiotics will remove the infection, and the pain will disappear.

Chronic pain treatment

A range of nondrug therapies can help relieve pain. These alternatives to medication may be more suitable for people experiencing chronic pain.

These therapies include:

  • Acupuncture: Inserting very fine needles at specific pressure points may reduce pain.
  • Nerve blocks: These injections can numb a group of nerves that act as a source of pain for a specific limb or body part.
  • Psychotherapy: This type of therapy can help with the emotional side of ongoing pain. Chronic pain can often affect a person’s enjoyment of everyday activities and reduce their ability to work. A psychotherapist can help a person enhance their understanding of pain and implement lifestyle changes to minimize the intensity of the pain and build coping skills.
  • Transcutaneous electrical nerve stimulation (TENS): TENS aims to stimulate the brain’s opioid and pain gate systems and thus provide relief.
  • Surgery: Various surgeries on the nerves, brain, and spine are possible for treating chronic pain. These include rhizotomy, decompression, and electrical deep brain and spinal cord stimulation procedures.
  • Biofeedback: Through this mind-body technique, a person can learn to control their organs and automatic processes, such as their heart rate, with their thoughts more effectively. Virtual reality may now play a role in the use of biofeedback in pain management, according to 2019 research.
  • Relaxation therapies: These include a wide range of controlled relaxation techniques and exercises, mostly in the realm of alternative and complementary medicine. A person can try hypnosis, yoga, meditation, massage therapy, distraction techniques, tai chi, or a combination of these practices.
  • Physical manipulation: A physiotherapist or chiropractor can sometimes help relieve pain by manipulating the tension from a person’s back.
  • Heat and cold: Using hot and cold packs can help. People can alternate these or select them according to the type of injury or pain. Some topical medications have a warming effect when a person applies them to the affected area.
  • Rest: If pain occurs due to an injury or overworking a part of the body, rest may be the best option.

With adequate pain management, it is possible to maintain daily activities, social engagement, and an active quality of life.

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Q:

Is there any research on what the most painful type of injury is?

A:

There is a lot of research on pain and varying reports on what is the most painful. Nerve pain — for example, cluster headaches, shingles, or a pinched spinal nerve from a herniated disc — often tops the charts.

Deep visceral pain, such as the pain that occurs with peritonitis, childbirth, or kidney stones, ranks high on the worst pain scale. Burns are especially painful, depending on the severity.

However, many factors affect the severity of pain, including the subjective tolerance of the individual.

Deborah Weatherspoon, Ph.D., R.N., CRNA Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.