Pain; What Can Be Done When the Pain Won't Go Away
Weck, Egon, FDA Consumer
PAIN WHAT CAN BE DONE WHEN THE PAIN WON'T GO AWAY
Smash a finger while hammering and your body responds with a jolt of pain that overpowers your other senses and commands: "Stop, you've injured your finger!"
Reacting to the sudden pang and the soreness that follows the blow, you immobilize and favor the hurt finger and thereby promote healing.
For the fact is, pain plays a vital biological function. Its importance is dramatically illustrated by people who are unable to feel pain because of disease or injury. Lacking this important warning system, they suffer cuts, burns, broken bones, and other injuries that a sense of pain helps most of us either avoid or react to quickly, preventing worse injury.
But not all pain is useful. Chronic pain that persists long after its cause has been diagnosed serves only to torment the patient. Produced by conditions like a nerve or back injury or cancer, chronic pain has been compared to a burglar alarm that can't be switched off.
The more research scientists learn about the nature and physiology of pain, the more complex it seems to be. Only recently have medical scientists begun to understand the mechanism of pain. Armed with greater knowledge, they hope to mobilize new resources to control pain.
Moreover, interdisciplinary medical teams focusing on pain at hospitals and pain treatment centers are developing new strategies to treat pain more effectively with traditional painkilling medicines and techniques.
Blocking the Pain Pathway
Pain impulses are sent from the site of the damage to the spinal cord and then on to the brain. The pain from that misdirected hammer blow, for example, is flashed to the nervous system from nociceptors, pain receptors in peripheral tissues--in this case, your thumb. Damaged cells release substances that raise the sensitivity of nociceptors, causing them to send out strong pain pulses.
Prostaglandins are a group of sensitizing substances produced by injured cells. Aspirin and aspirin-like compounds kill pain by inhibiting prostaglandin production by cells of the peripheral nervous system.
Pain can be stopped further up the line--in the spinal cord. Pain impulses originating in peripheral nerves--in your smashed thumb, for instance--travel along special nerve fibers to cells in a part of the spinal cord known as the dorsal horn. In the microscopic spaces--called synapses--between dorsal horn cells, chemical neurotransmitters enable pain messages to move from one cell to the next on their way to the brain. The dorsal horn cells, however, release a neurotransmitter called serotonin that blocks the passage of pain impulses between cells. Antidepressant drugs such as amitriptyline are thought to prevent nerve cells from pulling serotonin out of the synapses between dorsal horn cells, which may explain why these drugs can relieve pain.
Clinicians are now trying amitriptyline and newer tricyclic antidepressant drugs such as desipramine in patients suffering pain caused by shingles and to treat the severe burning foot pain sometimes associated with diabetes.
Moreover, they are looking for the substances involved in pain transmission from the peripheral nerve cells to the dorsal horn so they can suppress pain even earlier along this route.
Pain impulses ascend from the spinal cord to the thalamus in the midbrain and then to the cerebral cortex. Morphine, codeline, and other drugs derived from the opium poppy have long been used to control severe pain by causing the brain to suppress pain messages received from the dorsal horn. Synthetic opiates include methadone, hydromorphone and meperidine.
While both natural and synthetic opiate drugs are very effective in handling severe pain, they can have bothersome side effects, including nausea, drowsiness, constipation, and mood changes.
One of the most important breakthroughs in pain research in the past decade was the discovery that the body makes its own opiates--endorphins, enkephalins and dynorphins. …