Pain

Abstract

Pain affects every living creature at some point in their lives, but we actually know very little about the systems involved in pain. The subjective nature of pain and a dearth of effective tests add extra challenges to the study of pain. Harmful stimulus drives complex mechanisms into action during the pain response. Many chemicals and hormones are affected by this response and, in turn, affect organ systems and bodily function. Prolonged episodes of stress and unresolved pain can lead to a host of medical and behavioral issues when the body’s systems cannot restart or the hormones necessary for survival run wild in the body. Some of these chemicals and hormones may offer potential treatments and cures for pain, however – with enough

time and research. Many medicines and treatment options are presently available to patients suffering from pain, but not all medicines are equal. Some medicines only treat certain varieties of pain and may not even help all people with the same variety of pain. The problem of drug addiction throws even more difficulties to the situation. Without unbiased medical testing, medical professionals must choose who really feels pain and who simply feeds an addiction.

Greater Management of Pain Through Greater Understanding of the Pain Response
The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” Everyone understands pain personally, but surprisingly few people understand the mechanisms and physical reasons behind pain.

Even doctors and scientists work with only a rudimentary knowledge of how and why pain occurs. The complexity and the personal nature of pain make research and advancement a challenging problem. Most modern tests cannot fully account for pain – scans and laboratory tests cannot document the severity of pain, but many tests can reveal pain-related chemicals in the body and potential physical or disease causes. After ruling out potential physical causes, doctors must rely on the patient’s own description of the pain in order to properly treat or manage the

pain.
Physicians classify pain as either acute or chronic. To make the distinction as easy possible, doctors generally agree any pain lasting less than six months is acute and any pain lasting longer than six months is chronic. Acute pain generally comes with a clear cause, such as inflammation, injury, or disease. Generally, this pain is a defensive mechanism to protect the body from harm such as overuse or injury. Acute pain often occurs suddenly and may present with emotional distress. This type of pain lasts for a certain time and usually remains within a specific range of severity. As a result, acute pain is relatively easy to diagnose and treat (“Pain: Hope through research,” n.d.).
Chronic pain is ongoing or reoccurring pain, which may result from many conditions and factors. Typically, chronic pain is difficult to diagnose, resists treatment, and persists over long periods. Physicians consider chronic pain a chronic disease condition much in the same mode as asthma or diabetes. The causes of chronic pain are varied and hard to determine; some causes include multiple physical disorders, neurological conditions, and previous trauma (“Pain: Hope …,” n.d.). An estimated 116 million American adults suffer from chronic pain – a damage to the American economy of between $560 million and $635 million in lost productivity and medical expenses. Worldwide, researchers estimate 20 to 25 percent of the human population suffers from chronic pain (“Researchers gain insight …,” 2014).
Detection of Pain
Several methods see use in the determination of pain levels in various groups of patients. With adults or older children, professionals employ the use of to assess pain. The patient labels their pain as a number between one (no pain) and ten (the worst pain ever). After a numerical value, adults and older children are usually simple; a coherent patient in pain can describe the pain as stinging, burning, aching, throbbing, etc. Children or incoherent adults may not be capable of labelling their pain. In these cases, the Wong-Baker Faces Pain Rating Scale offers a visual analysis tool. The scale displays six faces labeled zero through five. The zeroth face represents no pain with a happy smile and relaxed expression while the fifth face represents the most pain with a frown, tears, and upset expression. Professionals may also use this scale to determine pain based on a patient’s facial expression when the patient cannot or will not communicate (Graham, 2013).
As previously stated, very few laboratory or medical tests help determine severity or complex causes of pain. Simple tests can identify physical or disease-related causes of pain, however. Foreign objects, broken bones, lacerations, burns, and blockages can all be easily verified through medical tests. Animal bites, ingestion of hazardous liquids, and inhalation of hazardous gases are more complex but usually simple to determine. If no obvious cause for pain can be determined, doctors must move on to more sophisticated methods and tests. For truly challenging and rare issues, the various tests and doctor visits may take months or even years. Even after months of testing, sometimes no clear cause can be found. In these cases, doctors must help the patient manage the pain and hope advancing technologies and research can provide a diagnosis, and ultimately a cure or better treatment plan, in the future.
Mechanism of Pain
The pain system begins with unpleasant stimulus – for example, stepping on a stray rock while barefoot.

The nerve fibers in the foot form part of a nociceptor, a special receptor found all over the body, and start the pain process. The receptors translate the stimulus into an electrical impulse and send the impulse up the leg and towards the spine. A cluster of specialized cells in the spinal cord forms the dorsal horn, which processes the impulse into the spinal cord. The dorsal horn then sends the signal on to the brain, but the horn may also inhibit or amplify the impulse before sending it onward. After the dorsal horn, the signal travels through the neurons of the spinal cord, into the brain, and to the thalamus. The thalamus relays the signal to the somatosensory cortex, the frontal cortex, the limbic system, and other regions of the brain. The somatosensory cortex senses the pain to localize the affected area. The frontal cortex “thinks” about the signal to determine how best to escape and avoid the pain. The limbic system reacts to the pain on an emotional level, determining how unpleasant or tolerable the pain feels. Pain to the head and face take a shortcut through the brain stem to the thalamus (“The trouble with treating pain,”

2014).
Put in such a clear series, pain seems relatively simple to understand. Any number of factors changes the situation – even race and sex affect the severity and perception of pain. Staggering amounts of processes happen in conjunction with and in the background of the pain response. Studies have proven many areas of the brain involved with pain are also used to experience basic emotions. The systems involved with negative emotions in particular also amplify pain signals (“The trouble …,” 2014).
Chemicals and Their Potential Uses for Treatment
The nervous system employs chemical messengers labeled neurotransmitters to communicate among neurons. Neurons release the transmitters to targeted cells where the transmitters bind to protein receptors. The receptor then functions as a gate – closing to block signals or opening to send signals on down the line. Inhibitory (closed) receptors and excitatory (open) receptors function in many systems, but in the pain system, these receptors enhance or dampen the body’s response to painful stimuli. Many natural and synthetic chemicals and transmitters receive focus in the study of pain in the hopes of finding more effective treatment and control options (“Pain: Hope,” n.d.)
One excitatory neurotransmitter important to the pain system is glutamate. Glutamate heightens sensitivity to pain by boosting responsiveness of excitatory receptors in the dorsal horn and brain. Current research focuses a good deal of attention on developing medicines to block specific receptors for glutamate to reduce pain. Gamma-aminobutyric acid (GABA) functions to reduce pain by inhibiting spinal neurons from sending pain signals. Unfortunately, GABA affects neurons beyond the pain system, making it a poor target for pain medication. Norepinephrine and serotonin transmitters block incoming pain signals from the brain down. Some medicines regulating these transmitters effectively treat some chronic conditions, and serotonin receptor modulation in particular effectively treats acute migraines. Opioids add another difficult element to pain. Several opioid peptides naturally occur in the body and serve as natural painkillers and mood enhancers such as the “runner’s high” during exercise. Enkephalins, dynorphions, and endorphins are opioids produced naturally in the body to stop pain, although endorphins in particular are better known for feelings of well-being, such as the aforementioned “runners’ high.” Synthetic and natural opioids are often successfully prescribed for pain due to their potency, but they also pose a very high risk for addiction (“The trouble …,” 2014).
Pain because of immune issues requires special attention. Many disease processes inflict pain but are easily diagnosed and treated. Inflammation in particular poses extra problems. While usually a symptom of a separate issue, on occasion the body suffers inflammation for no reason. This inflammation without reason usually results from cytokines – specialized proteins belonging to the nervous and immune systems. Typically triggered in response to disease or injury, these cytokines multiply in the brain, spinal cord, and at the site of injury. Unfortunately, cytokines sometimes trigger the inflammation signal without disease or injury. Even worse, perhaps, we presently know very little about the specific roles and triggers of cytokines. With further research into the nature of cytokines, hopefully new medicines can be developed to block or reduce inflammation resulting from cytokine activity (“Pain: Hope …,” n.d.).
Effects of Pain on Bodily Function
While the body chemically and electrically responds to unpleasant or noxious stimuli, several other effects begin to take place. One of the most obvious accessory effects is the “fight or flight” response. Acute, severe pain in particular triggers the endocrine system to release or increase stress-related hormones in the bloodstream: adrenocorticotrophic hormone (ACTH), antidiuretic hormone (ADH), catecholamines, glucagon, and angiotensin. Corticotrophin-releasing hormone (CRH) also releases in order to trigger ACTH synthesis and activation of the sympathetic nervous system. CRH also increases heart rate and blood pressure. The rising levels of ACTH signal the production of cortisol to maintain metabolism and blood glucose levels during the stressful period. Cortisol also suppresses prostaglandin activity to reduce any inflammatory response. Two specific catecholamines, adrenaline and noradrenaline, are released to boost blood pressure by constricting blood vessels and improve oxygenation by dilating small passages of the lungs. Increasing adrenaline levels also heighten emotional and conscious awareness during the stress response. Glucagon increases the metabolic rate and stimulates the release of glucose from the liver to the bloodstream for use by critical organs – specifically the brain. ADH during the stress response causes the body to retain water and sodium and affects blood pressure (Middleton, 2003).
Once activated by CRH, the sympathetic nervous system utilizes the various released hormones to achieve specific goals for immediate survival. The sympathetic nervous system coordinates the available hormones and materials to stimulate the respiratory system in order to increase oxygen intake by dilation of the bronchioles. The heart is also stimulated to improve circulation, thereby affecting blood pressure and flow. The sympathetic nervous system inhibits systems and processes deemed unnecessary for immediate survival – specifically digestion by preventing or reducing secretion of digestive enzymes and peristaltic action of the gut. In the short term, all of these effects are important and beneficial. If the stressful situation persists or the body cannot keep up with its own demands, these beneficial reactions can quickly become negative. The stress on the cardiovascular system may lead to tachycardia, hypertension, myocardial ischemia, myocardial infarction, and pulmonary embolism. The reduction of gastrointestinal function reduces gut motility and may develop into paralytic ileus. The inability or unwillingness to cough up secretions may lead to pneumonia or atelectasis. Pulmonary dysfunctions may result in hypoxia. Suppression of immune functions can lead to a host of unpleasant diseases and syndromes, including sepsis. Along with the physical ailments from persistent stress, cognitive and behavioral functions can be impaired. Unrelieved pain or prolonged stress responses may result in anxiety issues, insomnia, disorientation, confusion, and loss of concentration. All of these factors can ruin a patient’s quality of life and ability to function (Middleton, 2003).
Treatment and Management of Pain
Pain in the acute sense obviously ruins short-term productivity and happiness, but long-term pain may even ruin a person’s entire life. While not all pain can be cured, all pain can be treated. Unfortunately, no one medicine effectively treats all types of pain. Various methods of treatment and medicines exist to improve individuals’ lives by allowing them to work, play, and live with less or no pain. While medications are sometimes the only method to provide true relief, an individual should explore other options either in conjunction with or in place of medications (“Pain: Hope …,” n.d.).
Various therapy programs can assist pain management and offer relief for patients leery of medications. Many acute injuries are remedied with physical therapy; even some chronic pain issues may be resolved by careful, guided exercise. Cognitive and behavioral therapies offer psychological approach to pain management. Psychological treatment options offer methods for coping, addressing negative thoughts and emotions, and preparing for impending pain such as planned surgeries and childbirth (“Pain Management,” n.d.). Counseling and support groups offer emotional and psychological support to patients. Several studies demonstrate an impressive effect relating to human interaction – actually asking how a patient feels leads to more satisfaction with treatment and less complaints about pain (“The trouble …,” 2014).
Medications used for pain management vary widely, from over the counter medications to strictly controlled narcotics, but all share one purpose – to stop pain. If the underlying causes have been treated but pain persists, the goal is then to manage pain via one of two methods: analgesia or anesthesia. Analgesics reduce pain but do not completely remove the response, whereas anesthetics completely remove pain (“What is the …,” n.d.). Analgesics fall into one of two categories: narcotic and non-narcotic. Most narcotic analgesics are either opioids or opiates; these medicines decrease pain through complex physiological processes involving the nervous system. Narcotics bind receptors in the brain to stop the sensations of pain – put simply enough, the body still feels the pain, but the mind no longer cares. Non-narcotic analgesics encompass most common pain relievers, both prescription and over the counter. Non-steroidal anti-inflammatory drugs fall into this category. Anesthetics are classified as local, regional, or general anesthetics. Local anesthetics, for example lidocaine, target small areas of the body while the patient remains conscious. Regional anesthetics, such as an epidural, block pain to large areas of the body and must be injected in the spinal cord or near major nerve centers; the patient also remains conscious under the effects of regional anesthesia. General anesthetics are most often administered through either inhalation or intravenous injection. General anesthetics affect the entire body, removing all sensations by rendering the patient unconscious. Some commonly used general anesthetics are ketamine, propofol, nitrous oxide, and sevoflurane. Inhaled anesthetics are generally used to induce unconsciousness while intravenous types are usually used to maintain unconsciousness – such as for surgery (“Pain Relievers,” n.d.).
Doctors may also prescribe medicines beyond traditional painkillers, either to treat a specific type of pain or to help a patient resistant to certain types of medicines. Anticonvulsants, antidepressants, beta-blockers, and anxiolytics all function differently to reduce or eliminate specific types of pain. Antidepressants are often prescribed to treat chronic pain in conjunction with other medicines. Anticonvulsants most often help with pain specifically relating to the nervous system instead of injury. Beta-blockers are generally prescribed for migraines, but some anticonvulsants also treat migraines. Anxiolytics decrease activity of the central nervous system and act as muscle relaxants; due to the powerful effects of anxiolytics, physicians usually only prescribe this type as a last resort. All types of medication have very specific benefits and side effects, and no one combination or medicine works for every pain in every patient. Pain sufferers should consult with medical professionals to treat and determine the efficacy of treatments for their own individual situation (Rodriguez, n.d.).
Conclusion
To better treat and manage pain, we must first better understand pain. While we have a functional knowledge, we have far more left to learn about the pain response and pain systems. The need for further research is obvious, but progress is limited by technology and availability of subjects. Much can be learned from our fellow animals, but humans do differ greatly and our sentience offers unique challenges and possibilities. New technologies, chemicals, and research advance daily, however, offering hope for potential avenues of diagnosis and treatment in the future. Hopefully, medical and research technology will continue to progress rapidly and offer better instruments and tests to use in the study of pain. Once we understand the true nature of pain in the human body, perhaps we can find real cures for pain.