Chronic Pain and Opioid Use
Chronic Pain and Opioid Use Explained by Las Vegas, Summerlin, and Henderson Nevada’s Top Pain Doctors
Chronic pain is pain that occurs constantly, regularly, or recurrently over a considerable period of time, normally six months or more. The designation “chronic” can be applied depending on the condition in question, however. A more consistent definition may be pain that persists beyond a reasonable time expected for normal healing. Chronic pain may be low-lying and constant, or severe and occurring at certain times of day, every day. It is estimated that approximately 30% of all people in the U.S. suffer from chronic pain. Half of these people experience daily pain or rate their pain as severe (i.e. seven or more on a scale of one to ten).
Chronic pain is also correlated with lower income, indicating that many sufferers may be economically unable to seek consultation with a pain doctor about their symptoms. However, chronic pain can also gradually grow worse over time, particularly if left untreated. This type of pain can become severe enough to prevent normal function or movement, and may cause a sufferer to become unable to get out of bed or a chair for long periods of time. Chronic pain may also increase the risk of psychiatric conditions, such as depression. Pain can be experienced in a variety of locations, depending on the condition in question, or an underlying condition that may be the cause.
Chronic pain can be treated by a variety of procedures designed to block the transmission of those pain signals to the brain. The most common and effective, however, is pharmacotherapy. Some drugs can treat inflammation, a source of both acute and chronic pain, directly. Others activate pain-blocking receptors in the brain, spine, and body. There have been many drugs developed to do this in the last century, but none have approached the effectiveness of one of the oldest types of analgesics known: opioids. Opioids significantly block pain, but are also associated with abuse and mortality. Nonetheless, if used properly and responsibly, patients can achieve relief from pain, regain normal functions and abilities, and live normal, healthy lives. This article will discuss the role of opioids in chronic pain treatment, as well as the benefits and potential risks to patients.
Causes of Chronic Pain
One condition that is often treated with opioids is chronic back pain. Particularly prevalent in the lower back, this is a common condition that may be caused by several factors such as muscle strains, injuries, or infection. Chronic lower back pain may also be indicative of damage to certain spinal nerves, or the bones of the spine. Herniated (or bulging) intervertebral discs tend to occur in the vertebrae of the lower back. When discs in the lower back bulge, it can cause chronic lower back pain. Chronic pain in this region can also be caused by vertebral fractures. One type of these is a compression fracture, also known as collapsed vertebrae. Compression fractures are a common side-effect of diseases such as osteoporosis. These erode the bones until they collapse. This condition is associated mostly with people 50 years and older. Other types of minor fractures in vertebrae are usually a consequence of motor accidents, falls or other traumas, firearm-related injuries, or diving. They are most often associated with men ages 15 to 24 and people 55 years or older.
Chronic back pain can also be caused by spinal stenosis, a condition in which the spinal cord or spinal nerves are constricted by abnormal growth or scarring of the vertebrae. These often need surgical intervention, but if this can be avoided, the pain can be managed by pharmaceutical or other non-invasive options. Constant and long-term back pain can also be linked to surgical error. This can often result in inadvertent nerve damage, which in turn is a source of chronic pain. This is known as “failed back surgery syndrome.” Patients with this condition can become reliant on pain treatment for years afterward. Chronic lumbar pain can also be caused by conditions such as ankylosing spondolysis and arthritis.
Pain in the hips or legs is another component of many chronic pain cases. This can be caused by a number of factors, including injury, joint damage, and inflammation. The most common cause of chronic hip pain is a fracture in the joint, mostly seen in the elderly. This is mainly associated with osteoporosis, with or without a concomitant fall or accident. Fractures also occur in children, which is often associated with accidents sustained during normal activity (such as playing), and also with increased body mass. Hip arthroplasty, or replacement of parts of the joint with a prosthetic, is often needed after a fracture. This can cause chronic pain in itself, requiring management by pharmacological means or physical therapy. Hip replacements are also often needed in patients with osteoarthritis. This autoimmune condition causes chronic, painful inflammation of the joint. It is usually associated with older populations, although early-onset arthritis is increasing.
Another extremely prevalent type of chronic pain is headache. Most chronic headaches are those that occur consistently at certain times of day (“episodic” or “recurrent” headaches). It is estimated that nearly 50 million people in the U.S. suffer from recurrent headaches. Headaches are caused by chemical or physical damage of the structures surrounding the brain, including the skull, muscles, nerves, arteries, veins, subcutaneous tissue, eyes, ears, sinuses, and mucous membranes. This is usually the result of inflammation, injury, or disease. There is also increasing evidence that some types of headache are caused by damage to vertebrae or muscles in the neck, and that certain others may be caused by abnormalities in the pain-processing centers of the brain. These centers continually perceive any kind of signals from the face or skull as noxious (harmful or painful). This may be supported by observations that patients with chronic headaches are more sensitive to pain than normal counterparts, and have deficits in the neural circuits that control pain signals.
Migraines are a large component of refractory chronic headaches. They are considered the most common of all primary (singular condition) headaches by researchers in this field. The number of new migraine cases per year is reported to be as high as 12% of the U.S. population. Women are three times more likely to experience migraine pain across the course of their lifetime than men. Some experience chronic migraines associated with their menstrual cycle. Migraine headaches are typically characterized by intense episodes of severe, throbbing pain within the head. Migraines are usually felt just behind or above one eye (unilateral). The pain may spread to other areas of the face over time, especially if left untreated. They may also be accompanied by sensitivity to light, sound or odors, or by nausea or vomiting. Migraine symptoms can last several hours or even a number of days.
Cluster-type headaches are typically experienced as severe pain over an eye or the temple, often unilaterally. They can be characterized as a succession of headaches, occurring with a frequency as high as eight in one day. They occur frequently at night, and the pain is reported to wake patients from sleep. The pain may last from thirty minutes to two hours. Cluster headaches are most common in men that are 20 to 40 years old. They are thought to affect 0.01% of the world’s population.
Tension-type headaches are often described as extreme pressure around the forehead or head. They can also be associated with throbbing, stabbing, or grinding pain in the facial muscles. Patients may experience light and sound sensitivities accompanying the pain. Tension headaches can last from 30 minutes to several days. Chronic tension-type headaches occur on fifteen days or more per month. Tension headaches are the most common type of headache, affecting approximately 3% of the total population. Headaches are the leading cause of all over-the-counter medication intake and a prominent source of requests for prescription medication.
There are other sources of chronic pain associated with a variety of areas of the body. Chronic pain may be experienced in the testicles, which is often the result of inflammation or infection. Chronic pain in the feet is associated with abnormalities or damage in the heels or toes. Chronic facial pain is most often associated with damage to certain major cranial nerves, or important nerve clusters (ganglia) located in the skull and associated with control of the face or jaw. Other types of chronic pain include diabetic neuropathy (a type of nerve damage associated with diabetes), postherpetic neuralgia (severe neural tissue caused by herpes zoster infection), and Crohn’s disease (an autoimmune disease affecting the digestive system).
Cancer is also a major factor of chronic pain. Cancer-related chronic headache is common, as is hip and back pain. Cancer in bones and joints causes chronic pain, as do metastases invading bone and tissue surrounding the original tumors. Chronic pain following cancer treatment is common, as either radiotherapy or chemotherapy can cause damage to healthy tissues in the vicinity of a tumor. This often results in consistent levels of pain that can last from months to years. This must be managed by pharmacotherapy or other procedures. Chronic pain is also a diagnostic marker of cancer developing in the affected area.
Opioids as a Treatment for Chronic Pain
Pain is the response of the nervous system to potentially harmful and dangerous stimuli to the tissues (e.g. muscle, nerve, and bone) in contact with it. The sensation of pain, or nociception, is sent to the brain via the spinal cord. Pain signals are initially transmitted to the spine and sent from there to the relevant regions of the brain. Specific parts of the nerves (known as “pain fibers”) conduct noxious stimuli to the dorsal horn region of the spinal cord. Pain fibers then stimulate neurons within the dorsal horn to transmit this signal to the central nervous system.
Nociceptive transmission is not that straightforward however; the dorsal horn itself is also regulated by large populations of mu receptors, which when activated can significantly inhibit nociceptive stimulation and transmission. These receptors are strongly associated with opioids. Drugs of this chemical conformation have strong affinity and efficacy (the ability to bind to and activate) at mu receptors and produce a powerful and long-lasting pain-relieving effect. Opioids, such as morphine and heroin, have been used throughout history for their pain-blocking (and recreational abuse) potential. Newer opioids in use today also include oxycodone, fentanyl, and codeine.
Risks and Adverse Effects of Opioid Use
Opioid activity at the dorsal horn (and the other opioid receptors located in the spine, brain, and other areas of the body) can result in other effects beyond pain blocking. These include a sense of euphoria, numbness, lethargy, drowsiness, and even hallucination. More adverse effects include nausea, vomiting, itching, dry mouth, delirium, hypothermia, and constipation. In severe cases, respiratory depression and irregularities in heartbeat (i.e. bradycardia or tachycardia) can develop. Overdoses of opioids can cause asphyxia and fatal respiratory depression, if not treated appropriately and quickly. Less well-known adverse effects of opioids are their effect on the immune system. For example, it was found that morphine administration results in a reduction of the B cell-mediated immune response. Opioids are also counter-indicated in patients that have or are at a high risk of renal failure, as some of the metabolites of these drugs (i.e. their glucuronides) can exacerbate kidney damage. They also cause miosis (shrinking of the pupil).
Opioids are commonly associated with a high probability of tolerance, dependence, and addiction. Tolerance is developed when the same dose of a drug is less effective over time. Opioids produce tolerance in humans at a quicker rate than many other drugs. There are a number of theories as to why this is, including changes in receptor population or activity in response to the drugs. Individuals with an especially low tolerance (conferred by either genetic predisposition or certain conditions) are at a higher risk of toxicity caused by opioids, particularly morphine, which can be fatal. The development of tolerance may cause a patient to seek a higher dose to relieve pain, thus increasing the probability of adverse effects, and of another major risk associated with opioid use: dependence. There are two main types of drug dependence–psychological and physiological, wherein the body reacts to discontinued use with harmful physical effects, such as a magnification of the condition treated. A painful condition may be perceived as much worse in the absence of opioid administration, due to physical dependence.
Physiological dependence also causes the symptoms of withdrawal, a series of negative side-effects in the event of reduction or discontinuation of certain drugs, such as opioids and benzodiazepines. Opioid withdrawal can be difficult to overcome, but is not as severe as withdrawal from other drugs such as alcohol. The first stage of opioid withdrawal often takes the form of intense drug craving, anxiety, irritability, negative mood (to the extent of mild depressive symptoms), and uncontrollable perspiration. The patient may experience compulsive yawning, running nose and eyes, and continuation of the first-stage emotional symptoms. At about 24 hours after discontinuation, dilated pupils, goose bumps, muscle twitches, fluctuations in body temperature, aches, and loss of appetite may occur. The next stage may include intestinal cramping and restless leg syndrome, loose stool, nausea, insomnia, elevation of blood pressure, tachycardia, and restlessness. At 36 to 72 hours into withdrawal, vomiting, severe diarrhea, and weight loss may occur. Even after withdrawal, hypertension, gastrointestinal disorders, and magnified sensitivity to pain may persist. Patients should be made aware of the probable severity of withdrawal before beginning a course of opioids.
Psychological dependence is based on a perceived need of mood- or pain-altering compounds to cope with or alleviate emotional or psychiatric stress. This is affected by risk factors such as a history of sexual or physical abuse. Socioeconomic factors may also play a role in psychological dependence, as may certain genetic polymorphisms conferring an increased probability of dependence. This type of dependence is a major component of addiction, with which opioids are typically linked. Recent research has found that the tendency of chronic pain patients to develop addiction or opioid abuse is low, however. A 2013 article reported that just 1.9% of 216 patients studied were diagnosed with substance abuse problems. The risk of addiction may be associated with incomplete or unsatisfactory treatment of chronic pain, which may incite a patient to overuse their prescribed medication, or to seek additional drugs, opioid or otherwise, to supplement their effects. This is known as diversion, and often comes in the form of supplementing, mostly with benzodiazepines, or sourcing other opioids by illegal means.
There are other risks associated with opioid use. These include a lack of alertness and motion control, most often associated with higher doses. This may affect the ability of patients to undertake activities such as driving, although some studies suggest that tolerance over time enables longer-term users to do this with complete competence and safety. Patients receiving high-dose administration may still require vigilance, however, due to the risks of serious adverse effects, such as respiratory depression. Factors such as advanced age and pulmonary conditions interact to elevate this risk to a life-threatening issue. Currently, there is an emerging body of evidence that the use of daily long-acting opioids may cause testosterone suppression, which leads to hypogonadism (shrinking of the testes) in men. It should be noted, however, that the risks of side-effects and adverse effects are reduced in otherwise healthy individuals with a normal tolerance level.
Types of Opioids Used for Pain Management
Opioids remain a popular and widespread option in analgesia (pain relief) to this day. They can elicit pain relief and the complete return of normal function in individuals whose chronic pain caused severe debility and the loss of mobility and normal activity. They are delivered or administered in a variety of methods, depending on the severity of the pain, the type of opioid used, or the condition of the patient. Morphine, the most popular, common, and one of the oldest form of opioid used in modern medicine, is delivered mainly via injection, though it is also available in a quick-release lozenge form. Morphine is one of the most effective opioids because it binds to and activates the mu receptors in the central nervous system particularly well. It also mimics endogenous opioids (i.e. opioid-like molecules such as endorphins that are produced naturally in the body). Its bioavailability approaches 100% if injected, though this falls to approximately half of this if taken orally.
Morphine is commonly associated with high risks of tolerance, dependence (both physical and psychological), and addiction, although recent studies suggest that these concerns are exaggerated. However, it has also been demonstrated that addicts have a higher preference for morphine and its analogue heroin over other opioids such as codeine. Tolerance is very rapid, although resistance to its analgesic effects develops later than resistance to its other effects, such as euphoria. The tolerance potential of morphine is thought to potentiate its dependence and addictive effects, though some researchers have found that other risk factors, such as emotional or psychological trauma skew the probability of addiction. However, morphine at stable, moderate doses has shown positive and safe outcomes in chronic pain management for millions of patients worldwide. Morphine is particularly effective in treating intractable lower back pain, hip pain, and post-operative pain. It may be indicated in very severe, treatment-resistant headache cases (mostly in short-acting form).
Oxycodone is a relatively new opioid, in comparison to morphine. It also acts at mu receptors. It is often taken in oral form. It is effective in treating chronic pain associated with neuropathy, neuralgia, phantom limb syndrome, hip damage, cancer, and Crohn’s disease. In the case of Crohn’s disease, it can also treat the diarrhea that is often a symptom of this disorder. Oxycodone is also associated with improvements in mood and quality of life in these patients. It is often combined with other compounds such as non-steroid anti-inflammatory drugs (NSAIDs) and acetaminophen. Oxycodone is also sometimes given in combination with anticonvulsants such as gabapentin, which may potentiate the effects of the opioid. The adverse effects of oxycodone are less severe than those of morphine, but the withdrawal symptoms are often reported as worse. Oxycodone (in the form of Oxycontin®, a controlled-release form) has been popularly linked to a high abuse potential, but this may be reduced by its reformulation, to deter tampering and misuse. Hydrocodone is a chemically similar opioid to oxycodone. It is the most commonly prescribed opioid (in an oral formulation with acetaminophen) in the United States. Hydrocodone is effective in treating cancer-related pain. It is linked to a high abuse potential, possibly due to its rate of prescription and thus availability, but it has been found to be less liable to abuse than oxycodone.
Fentanyl is a synthetic opioid that was developed in 1960. It is a hundred times more potent than morphine. Fentanyl is used in operative and post-operative analgesia, and in chronic pain management. It is available in transdermal patches that are placed directly onto the skin so that the opioid will sink into subcutaneous fat, and from there release slowly into the bloodstream. Fentanyl is also available as a lollipop, or rather a slow-release solid lozenge on a stick, that the patient can suck or lick as needed. These are effective in treating chronic back pain, neuropathic pain, and pain associated with arthritis. Fentanyl is also often delivered through an intrathecal pump. This is attached to a catheter inserted into the spinal fluid. The pump contains a reservoir of fentanyl, which the patient may be able to operate via a control device. The intrathecal pump is effective in treating cancer pain and back pain. The main adverse effects of fentanyl are similar to those of all opioids, but may also include stomach pains and discomfort, headache, trouble breathing, or shortness of breath, hypoventilation, and severe anxiety. Fentanyl may pose a high risk of respiratory depression in those with a low tolerance to opioids. It is increasingly associated with recreational abuse, though not among chronic pain patients.
Managing Opioid Use
Introducing opioid treatment for chronic pain should be considered a major step, and requires an often rigorous process of assessment of whether administration would be appropriate for each individual patient. Before prescribing these drugs, a physician should ensure the patient has had an insufficient response to the non-opioid pharmacological options, such as NSAIDs, anticonvulsants, or tricyclic antidepressants. This should be assessed by pain scores and patient reports. Screening of patients for abuse risk factors is also advised.
If opioid use is deemed necessary, and the patient is not at significant risk of becoming an abuser, monitoring of their intake may still be necessary. This can be done through documentation. Tracking pharmacy and prescription reports is useful in monitoring opioid intake. In addition, recording information such as dose, changes in pain severity, any adverse effects and the patient’s quality of life, mood, physical, and functional findings at each visit to the physician’s office is also a common practice. Urine testing may indicate abuse or diversion to other drugs. An increasingly common tool is a contract between the physician and patient, which stipulates rules to be followed, such as dose, intake per day, a single prescriber or pharmacy the patient will go to, non-diversion, and other important points of compliance. Patients who require high doses (e.g. the equivalent of 200mg morphine per day) may need to be monitored closely by a pain specialist or clinic. In general, physicians prescribing opioids should be very familiar with issues of opioid administration, risks, and addiction. It follows that patients may also benefit from similar education, as this may increase the probability of responsible intake and help them avoid misuse.
Screening and assessment tools in considering prescription of opioids are common and largely standardized. They include the Opioid Risk Tool, and the Screener and Opioid Assessment for Patients with Pain (SOAPP, of which there are standard, revised (-R), and short forms (-SF)). Monitoring and vigilance protocols or checklists are also increasingly popular, and their importance is increasingly regarded by physicians prescribing opioids. These are often based on the DEA recommendations regarding use of these drugs and their administration. In accordance with this, Nevada Pain Specialists have established a 12-step compliance checklist prior to prescription.
The 12-step compliance checklist includes the following steps:
- Recording of the patient’s pain score (0-10)
- A verification of the patient’s need for these drugs, including their condition
- Documentation of a clinical benefit from opioid treatment, e.g. return of function and/or significant pain reduction, that should follow
- Discuss and define the outcomes of treatment with the patient, so that they are aware of what to expect (e.g. what level of pain relief and/or functional improvement) as a result of opioid intake
- Obtaining an up-to-date list of the patient’s current medication
- Any records of substance abuse or of behavior to indicate this (e.g. the patient denies taking a medication or denies a history of high-dose intake) will be requisitioned
- If no records of substance abuse are found, a physical examination of the painful area will take place
- The risks and benefits of opioid intake will be explained to the patient
- Any additional evaluation and/or treatment will take place; for example, a patient may undergo psychiatric assessment for depression
- An updated pharmacy board review will take place
- A current urine drug screen will also be necessary
- If the above tests are passed, the patient will sign an Opioid Agreement (a contract similar to the example described above), and begin their treatment
Other aspects of opioid use concern dose and frequency of dose. A constant dose of morphine can consistently manage pain, despite user tolerance, for years. Studies indicate that stable dosing maintains satisfactory levels of pain management, quality of life ,and patient mood. If this regimen starts to fail in providing the necessary pain relief, steps such as altering the type of medication, or modifying a prescription to a combination therapy (e.g. adding an anticonvulsant or tricyclic antidepressant) may be of use. Simply increasing the dose of the opioid used should be avoided if possible. As worsening of pain may indicate an exacerbation of the existing condition, or the emergence of a new one, an examination in the office may be of benefit before considering this.
Physicians and specialists should also be aware of treatments for withdrawal, overdose, and serious adverse events, such as respiratory failure. Overdose can be treated using opioid blockers, which are opioid receptor antagonists. These are molecules that compete with drugs to bind to receptors, but do not activate them. In this way, they reverse the actions of the opioid molecules. If a patient needs to discontinue a course of opioids, antagonists are also used in treatment for withdrawal because they reduce the symptoms to some extent. Examples of opioid blockers include naloxone, the standard antagonist, and buprenorphine. This is a partial agonist and antagonist, having properties of both naloxone and opioids. It is effective in treating withdrawal, and has also been shown to be effective as a treatment in cases of chronic lower back pain. Transdermal buprenorphine patches are now indicated for this condition, and achieve both pain relief and a significant return to function.
Chronic pain is experienced in 30% of the population, with half of those sufferers experiencing pain daily. On average, chronic pain is rated as severe. Eventually, it may result in the sufferer becoming confined to a chair or bedridden. Pain can be experienced in any area of the body. Chronic pain can be treated by pharmacotherapy. The class of drugs known as opioids are among the most popular and effective in treating chronic pain. They are also associated with abuse and severe adverse effects, however.
Chronic pain conditions include lower back pain, hip pain, and headache. Migraine, cluster, and tension-type headaches all have chronic forms, and can be debilitating. Headaches are the leading cause of all over-the-counter medication intake, and a prominent source of requests for prescription medication. There are other sources of chronic pain, associated with a variety of areas of the body. They include diabetic neuropathy (a type of nerve damage associated with diabetes), postherpetic neuralgia (severe neural tissue caused by herpes zoster infection), and Crohn’s disease. Cancer and cancer treatments are also a major cause of chronic pain.
Opioids block pain by activating their receptors in the brain, body, and spinal cord to significantly inhibit nociceptive transmission. Opioids include morphine, heroin, oxycodone, and fentanyl. Opioid activity also elicits side-effects, including euphoria, lethargy, drowsiness, nausea, vomiting, itching, dry mouth, delirium, hypothermia, and constipation. Opioid overdose can cause asphyxia and fatal respiratory depression, if not treated appropriately and quickly. Opioids can also depress responses of the immune system. Opioids are also counter-indicated in patients with renal failure. They are commonly associated with a high probability of tolerance, dependence, and addiction. Tolerance is the increased resistance to the effect of the same dose of a drug over time.
Physiological (or physical) dependence can cause protracted, often unpleasant, withdrawal symptoms. Recent research has found that the tendency of chronic pain patients to develop addiction or opioid abuse may be lower than previously thought, however. The risk of patient addiction may be associated with incomplete or unsatisfactory treatment of their pain, which may result in a temptation to overuse the medication or to divert to other drugs or drug sources. Nevertheless, most healthy individuals with a normal tolerance level are not significantly affected by the risks or adverse effects. Opioids can help patients achieve significant pain relief and regaining of function in individuals whose chronic pain previously caused them severe debility. They are delivered or administered in a variety of methods, depending on the severity of the pain, the type of opioid used, and the condition of the patient.
A rigorous process of assessment should take place before the prescription of opioids to a patient. The physician should ensure the pain is resistant to any other drugs available. Screening of patients for abuse risk factors is also advised, using for example the Screener and Opioid Assessment for Patients with Pain (SOAPP). Monitoring and vigilance regimens based on DEA recommendations are also increasingly common practices. In accordance with this, Nevada Pain Specialists have designed their own Compliance Checklist for Long-Term Opioid Therapy. Patient education about opioid use, including details on withdrawal and abuse potential, and their adherence to a responsible routine of drug use, as outlined above, should ensure the benefits and minimize risks of opioid use for chronic pain management.
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