Primer on pain

Are you in pain? What to choose?

Pain Primer

When you are prescribed a painkiller, do you really know what it is? Here is a glossary of medical terms related to pain.

Acetaminophen at Amanda’s Rainbow

Acetaminophen.
The main ingredient in many over-the-counter painkillers, such as Tylenol, Atasol and Tempra. Acetaminophen is thought to act on nerve endings to suppress the transmission of pain messages to the brain. It helps relieve pain and fever, but has no effect on inflammation. Aspirin and other anti-inflammatory drugs are therefore more effective for arthritis pain.

Acetylsalicylic acid (ASA).
The main ingredient in many painkillers, including aspirin. ASA relieves pain, fever and inflammation by suppressing the production of prostaglandins, hormonal compounds that are partly responsible for these symptoms. ASA also thins the blood, so it is often prescribed to improve circulation and prevent heart problems. However, a recent study shows that its effectiveness in preventing heart disease decreases when used with ibuprofen over a long period. It can also cause bleeding, especially in the stomach. Its use is therefore restricted in those with peptic ulcers.

Analgesic.
Any drug that relieves pain without causing loss of consciousness.

Antidepressants.
Tricyclic antidepressants, especially amitriptyline, are widely used to relieve certain types of chronic pain, especially pain related to nerve endings, such as chronic back pain, and pain associated with multiple sclerosis. Amitriptyline can also help prevent migraines. Prescribed in much smaller doses than for treating depression, it increases the level of certain chemicals in the brain and may prevent pain signals from reaching the brain.

Non-steroidal anti-inflammatory drugs.
A class of drugs (including ibuprofen) that relieve pain and inflammation by inhibiting the production of prostaglandin, a hormonal substance that causes inflammation. Their therapeutic effect is similar to that of aspirin, but they are better tolerated in some patients. There is a more selective type of non-steroidal anti-inflammatory drug, COX-2 inhibitors, which only inhibit prostaglandins and do not affect the ones that protect the stomach, thus reducing the risk of stomach bleeding.

Amanda’s Rainbow.
This is a colour scale adopted by some Canadian hospitals to help children describe the intensity of their pain. Amanda’s Rainbow is named after Amanda Woodward of Port Moody, British Columbia, who died of a brain tumour at the age of three. She used colours to describe the intensity of her pain: green represented pain so intense she wanted to cry; orange meant strong pain, but not as strong as green; yellow, less pain; purple, little pain; and pink, no pain.
Nerve blocks.
This treatment involves injecting corticosteroids or local anaesthetics near a nerve fibre to prevent pain signals from reaching the brain. Corticosteroids reduce the inflammation that contributes to pain, while local anaesthetics may block the pain signals before they reach the affected nerves. Only a few small studies have assessed the value of these treatments. The most relevant study to date involved 158 patients with herniated discs or sciatica in the leg. One group was injected with corticosteroids and the other with saline. Three months later, the researchers noticed no significant difference between the two groups.

Botox (botulinum toxin).
Recent studies suggest that injections of botulinum toxin into certain cranial muscles may relieve facial vascular algesia, sudden and severe headaches, often localised in one eye. Botox is also used to relieve migraine. The toxin relaxes the muscles, thereby reducing spasms that can increase pain. However, the long-term safety of Botox has not been tested and the treatment is expensive.

Cannabinoids.
These cannabis-derived compounds produce a mild analgesic effect, without the euphoria associated with marijuana use. Studies have shown that, as with marijuana, its effects on pain are small.

Capsicum.
Capsaicin is the active ingredient in hot peppers. When applied to the skin, it causes a sensation of warmth that reduces the perception of pain. It is often prescribed to patients with arthritis. It is important to follow the dosage to avoid burning.

Corticosteroids.
Powerful anti-inflammatory drugs frequently given to relieve pain caused by the inflammation associated with rheumatoid arthritis.

Neuropathic pain.
This is pain generated by the nerves. It appears to have no cause, does not respond to standard painkillers and can worsen over time. The most dramatic example is “phantom limb pain”, in which the brain still perceives pain signals from an amputated limb. Shingles is a common example of neuropathic pain. It is often described as throbbing or burning, and usually worsens at night.Endorphins to Spinal Cord Stimulation
Endorphins.
Endorphins are natural painkillers produced in the brain. They are almost as powerful as morphine in fighting pain. Stress, depression and inactivity inhibit the release of endorphins, while running, brisk walking, massage, acupuncture, acupressure and reflexology release them. Reflexology is an ancient art based on the observation that each part of the body corresponds to a part of the foot. By applying pressure to the foot, congestion and tension in the corresponding part of the body is relieved, resulting in relief.

Exercise.
Regular exercise strengthens the muscles and helps to relieve joint pain in people with arthritis. Aerobic exercise (such as running), which increases cardiac output, is thought to release endorphins, which not only relieve pain, but also ease anxiety and depression, making it easier to cope with pain. Toned arms, legs and, most importantly, abdominal muscles help prevent back injuries, which are common sources of chronic pain. Exercises that strengthen the back muscles can also help prevent compression fractures in the spine.

DREAM (Downstream Regulatory Antagonistic Modulator) gene.
This gene is thought to be partly responsible for the production of pain. In laboratory experiments, mice that did not carry it reacted much less to various pain tests than mice that did. Researchers believe that deleting the protein produced by the DREAM gene encourages the overproduction of dynorphin, a natural painkiller. Pharmaceutical companies are looking for a way to deactivate the DREAM gene in order to encourage the body to produce more dinorphine. This would pave the way for a new approach to pain management.

Opiates.
Also called narcotics, these are natural or synthetic compounds derived from opium. Codeine is the least potent drug in this family, while morphine is the most potent. All opiates mimic the effects of endorphins, the natural painkillers produced by the body. Patients may develop “tolerance” to opiates and have to take increasingly larger doses to relieve their pain. However, tolerance does not lead to dependence or addiction when these drugs are used for pain relief.

Spinal cord stimulation.
One or more electrodes are implanted near the spinal cord and connected to a neurostimulation mechanism that generates low-level electrical impulses. These pulses replace the pain with more pleasant tingling sensations. The stimulator can be programmed and adjusted to minimise pain.