Everyone has experienced pain at some time or other. A cut, a sports injury, childbirth, surgery, or kidney stones all can produce varying degrees of pain. In these cases, the pain has a known cause and resolves when the cause is no longer there. This type of pain is acute pain. Acute pain performs a function – it warns the body of a problem or injury.
Chronic pain, which is pain lasting months or years, is much different. The pain itself rarely continues to perform a useful function. Chronic pain can be quite disabling, often preventing people from working and enjoying life. It can lead to people feeling isolated, angry, frustrated, and guilty.
Many medical conditions or injuries can cause chronic pain. Some people will continue to experience pain long after recovering from an initial injury, such as a back injury. Other chronic pain is caused by chronic diseases such as arthritis or cancer. Some people have pain that does not have an identifiable cause. This is not to say that the pain is not real. Whatever the cause, chronic pain is real and should be treated.
The following conditions may be associated with chronic pain:
- spinal injury
- back injury – the lower back is the most common site of chronic pain reported among chronic pain sufferers
- stomach ulcers
- nerve inflammation or damage
- mood and/or anxiety disorders
Sometimes pain can be felt in a part of the body that is no longer there. This is called phantom limb pain, which develops as a result of amputation. When pain in one part of the body is felt in another part of the body, it is called referred pain.
The internal organs are not very responsive to pain; instead, pain in these areas may be felt more as a diffuse pain (i.e., pain spread over a large area), which is not easy to localize.
Acute pain results when a disease or injury sends a signal to special sensory nerve endings called nociceptors. Nociceptors are located in the skin, as well as in other structures including blood vessels and tendons. Pain signals travel from the nociceptors, through the sensory nerves, and up the spinal cord to the thalamus in the brain. The signal is then sent to the cerebral cortex, the part of the brain that processes thought.
On the way to the brain, natural body chemicals can change the pain signal. Substance P makes the pain signal stronger. Endorphins make it weaker. Pain is not actually felt until the message or signals get to the brain. Chronic pain can originate at many points in the above pathway.
In some cases, chronic pain may arise from injury to the nerves in our body. This type of pain is called neuropathic pain and is often the result of direct injury or disease of the nerves. Neuropathic pain is different from acute, nociceptive pain – people often complain of sharp, burning, or radiating pain rather than dull, aching pain.
The cerebral cortex and the limbic system, which are the brain areas controlling emotion, process pain signals. How much pain is felt depends on a number of factors. Factors that increase how badly pain is felt include the following:
- previous bad experiences with pain
Anxiety can make pain much worse. Not knowing the cause of pain makes people anxious. The pain often seems less severe once they have a diagnosis of their medical condition. Worry about the seriousness of their condition can often also increase the severity of the pain.
Symptoms and Complications
Living with chronic pain can create a vicious cycle of anxiety, dependence on other people, and sleep deprivation. Chronic long-term pain can make it unpleasant for people to live their daily life normally and it saps their energy.
People suffering from chronic pain might stop social activities because of the pain. They might feel dependent on other people to help with daily tasks such as shopping. It can be hard to sleep for someone who is in pain, or worried about being in pain. Constant sleep deprivation can lead to depression. Feeling helpless because of chronic pain can also make people feel worthless and demoralized.
Making the Diagnosis
Pain that lasts longer than 6 months and doesn't respond to treatment is diagnosed as long-term chronic pain.
Although it can be hard to describe pain exactly, your doctor needs to know how it feels and where it's coming from, what aggravates the pain, how it impacts your daily life, and what makes it better. Doctors often use pain scales to help to rate the intensity.
In some cases, people suffering from chronic pain who have symptoms at multiple sites, become debilitated due to chronic pain, or who are not responding to pain medication or require more may be referred to a pain specialist.
Treatment and Prevention
Treatment for chronic pain blocks the pain signal anywhere in the pathway from the skin to the spinal cord nerves and from the spinal cord to the thalamus and cortex. Treatment ranges from traditional medications to alternative therapies.
Painkillers, also called analgesic medications, are often used to lessen chronic pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as acetylsalicylic acid* (ASA), ibuprofen, and naproxen can provide some relief. Acetaminophen is also commonly used. These medications are usually tried first. If they are ineffective, stronger medications such as opiates might be added.
Opiates (also referred to as narcotics) such as morphine and codeine, relieve pain. Opiates have caused concerns because they have been linked to dependence and addiction. They are the strongest analgesics available and have significant potential to become habit-forming and to cause drowsiness, nausea, constipation, and itching.
Although many people are afraid of becoming addicted to opiates, addiction is extremely rare when the medication is being used to treat pain. Addiction involves a psychological need to abuse drugs that is different from tolerance (needing higher doses of medication to keep the same level of pain control) and dependence (experiencing withdrawal symptoms if the medication is stopped suddenly).
Anesthetics such as lidocaine and mexiletene (given as ointments, patches, or oral medications) can relieve severe chronic pain if they're taken slowly and steadily in very small amounts.
Corticosteroids reduce the pain of bone cancer and anticonvulsant medications such as carbamazepine relieve the pain of damaged nerves. Some types of antidepressants are also helpful for nerve-related pain.
Transcutaneous electrical nerve stimulation (TENS) directs electrical energy to the painful sites on the body and blocks the transmission of pain signals. The energy starts a natural reaction in the spinal cord that relieves the pain. Not all people respond to TENS, but it takes away the pain completely for some individuals.
If someone suffers from chronic pain that's carried by one or more specific nerves, they can have a nerve block, which temporarily or permanently stops the pain signal from traveling along that particular nerve. An injected anesthetic blocks the nerve from carrying the pain signals. 50% of people are cured of the pain, and the remaining 50% have the pain return within a year. People can also have the nerves destroyed by surgery or by hot or cold treatments. The pain can return, however, and some people may lose feeling or movement in the part of the body controlled by the destroyed nerve.
In extreme cases, implantable nerve stimulators can be placed in the spinal cord and be used to change the sensation from pain to parasthesia (tingling).
Acupuncture is used to treat many painful conditions, including migraine and back pain. In acupuncture, the acupuncturist will insert thin needles just under the skin at specific points on the body. Acupuncture probably stimulates natural anti-pain chemicals in the spinal cord. Relaxation and meditation techniques can help relax muscles, relieve anxiety, and stop the cycle of pain.
Biofeedback relieves chronic pain very well. In biofeedback, an instrument measures breathing, heart rate, and other specific bodily responses and feeds them back in the form of light or sound. People can then learn to control these bodily responses through relaxation and cognitive techniques.
Various forms of psychological treatments have been used to help relieve chronic pain. Cognitive therapy can help people substitute positive thoughts for negative ones. Behaviour therapy tries to change the activity level of people with chronic pain.
*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.