Pain is an unpleasant sensation and emotional experience linked to tissue damage. Its purpose is to allow the body to react and prevent further tissue damage.
We feel pain when a signal is sent through nerve fibers to the brain for interpretation.
The experience of pain is different for everyone, and there are different ways of feeling and describing pain. This can makes it difficult to define and treat.
Pain can be short-term or long-term, it can stay in one place, or it can spread around the body.
Fast facts on pain:
Here are some key points about pain. More detail is in the main article.
- Pain results from tissue damage.
- It is a part of the body's defense mechanism. It warns us to take action to prevent further tissue damage.
- People experience and describe pain differently, and this makes it hard to diagnose.
- A range of medications and other treatments can help relieve pain, depending on the cause.
Pain is felt when special nerves that detect tissue damage send signals to transmit information about the damage along the spinal cord to the brain. These nerves are known as nociceptors.
The brain then decides what to do about the pain.
For example, if you touch a hot surface, a message will travel through a reflex arc in the spinal cord and cause an immediate contraction of the muscles. This contraction will pull your hand away from the hot surface.
This happens so fast that the message doesn't even reach the brain. However, the pain message will continue to the brain. Once there, it will cause an unpleasant sensation of pain to be felt.
How an individual's brain interprets these signals and the efficiency of the communication channel between the nociceptors and the brain dictate how people feel pain.
The brain may also release feel-good chemicals such as dopamine to counter the unpleasant effects of the pain.
Researchers estimate that pain costs the United States (U.S.) between $560 billion and $635 billion each year in treatment costs, lost wages, and missed days of work.
Pain can be acute or chronic.
Acute pain is generally intense and short-lived. It is the body's way of alerting a person to an injury or localized tissue damage. Treating the underlying injury normally resolves this type of pain.
The body's "fight-or-flight" mechanism is triggered by acute pain, often resulting in faster heartbeats and breathing rates.
There are different types of acute pain:
- Somatic pain is superficial pain that is felt on the skin or soft tissues just below the skin.
- Visceral pain originates in the internal organs and the linings of cavities in the body.
- Referred pain is felt at a location different to the source of tissue damage, such the shoulder pain felt during a heart attack.
Chronic pain lasts far longer than acute pain. It often cannot be resolved. It can be mild or severe, it can be continuous, as in arthritis, or it can be intermittent, as in migraines. Intermittent pain occurs on repeated occasions but stops in between.
The "fight-or-flight" reactions eventually stop in cases of 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 can overstimulate the nerve fibers.
This is known as "windup," a term that compares the accumulation of these electrical signals to a windup toy. Winding a toy with more intensity leads the toy to run faster for longer. Chronic pain works in the same way. This is why pain may be felt long after the pain-causing event.
There are other, more specialized ways of describing pain.
Neuropathic pain: This follows injury to the peripheral nerves that connect the brain and spinal cord to the rest of the body. It can take the form of electric shock-like pain, tenderness, numbness, tingling, and discomfort.
Phantom pain: occurs after the amputation of a limb and refers to painful sensations given out by the missing limb. It affects some 70 percent of amputees.
Central pain: is often caused by infarction, abscess, tumors, degeneration, or hemorrhage in the brain and spinal cord. Central pain is ongoing and can range from mild to extremely painful. Patients report burning, aching, and pressing sensations.
Knowing how to describe pain can help a person get a more specific diagnosis.
Diagnosis depends on an individual's subjective description of the pain. There is no objective scale for identifying the type of pain, so the doctor will take a pain history.
The patient will be able to describe:
- the character of all pains felt by the patient, such as burning, stinging, or stabbing
- the site, quality, and radiation of pain, or where the pain is felt, what it feels like, and how far it feels like it spreads
- what factors aggravate and relieve the pain
- when the pain occurs throughout the day
- the impact on the person's daily function and mood
- the person's understanding of their pain
A number of systems can identify and grade pain, but the most important factor in getting an accurate diagnosis is for the patient and doctor to communicate as clearly as possible.
Some of the pain measures used are:
- Numerical rating scales: These measure pain on a scale of 0 to 10, where 0 means no pain at all and 10 means the worst pain imaginable. It is useful for gauging changing pain levels in response to treatment or a deteriorating condition.
- Verbal descriptor scale: This may be used to measure cognitively impaired children, seniors, or people with autism or dyslexia. Instead of numbers, different descriptive questions are asked to narrow down the type of pain the patient is feeling.
- Faces scale: A series of faces is shown to the person in pain, ranging from distressed to happy. This is mainly used with children and has also shown effective responses in people with autism.
- Brief pain inventory: This is a more detailed written questionnaire gauging the effect of pain on mood, activity, sleep patterns, and how the pain may have affected the patient's interpersonal relationships. It also charts the timeline of the pain to detect any patterns.
- McGill Pain Questionnaire: This encourages people to choose words from 20 word groups to get an in-depth understanding of how the pain is felt. Group 6, for example, is "tugging, pulling, wrenching" and group 9 is "dull, sore, hurting, aching, heavy."
Other indicators of pain
When people with cognitive impairments cannot accurately describe their pain, there can be clear indicators as to the presence of pain. These include:
- moaning and groaning
- resistance to care
- reduced social interactions
- increased wandering
- not eating
- sleeping problems
If treatable, the doctor will either treat the underlying, pain-causing problem or prescribe painkilling treatment, such as medicine, to manage the pain.
Different types of pain will be treated 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 medicines.
Non-steroidal anti-inflammatories (NSAIDs) are a type of analgesic, or painkiller, that can reduce pain and help the 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.
Always read the packaging to find out what's in an analgesic before use and to check the maximum dosage. Never exceed the recommended dose.
Opioids are prescribed for the most extreme acute pains, such as following surgery, burns, cancer, and bone fractures. Opioids are highly addictive, cause withdrawal symptoms, and lose effectiveness over time. They need a prescription.
In severe trauma and pain situations, the doctor will carefully manage and administer the dose, gradually reducing the dosage to minimize withdrawal symptoms.
Discuss all medication options carefully with a doctor, and disclose any conditions and current medications. COPD, kidney disease, liver problems, previous drug addictions, and dementia can all be seriously affected by opioids.
Alternatives to medication
A range of non-drug therapies can help relieve pain.
- Acupuncture: The use of needles at certain pressure points can provide an analgesic effect.
- Nerve blocks: These injections can numb a group of nerves acting as a source of pain for a specific limb or body part.
- Psychotherapy: This can help with the emotional side of ongoing pain. Chronic pain can often affect the enjoyment of everyday activities and can lead to not being able to work. A psychotherapist can help to enhance understanding and put in place lifestyle changes to enable these parts of life.
- Transcutaneous electrical nerves stimulation (TENS): TENS aims to stimulate the brain's opioid and pain gate systems to provide relief.
- Surgery: Various surgeries of the nerves, brain, and spine are possible to relieve chronic pain. These include rhizotomy, decompression, and electrical deep brain and spinal cord stimulation procedures.
- Biofeedback: This is a mind-body technique. Through biofeedback, people can learn to better control their organs and automatic processes, such as their heart rate, with their thoughts.
- Relaxation therapies: This covers a wide range of controlled relaxation techniques and exercises, mostly in the realm of alternative and complementary medicine. This can include hypnosis, yoga, meditation, massage therapy, distraction techniques, and tai chi.
- 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. These can be alternated or selected according to the type of injury or pain. Some medications have a warming effect when applied topically to the affected part.
- Rest: If the pain is due to an injury or a repetitive action, rest may be the best option.
With effective pain management, it is possible to maintain daily activities, social engagement, and an active quality of life.