Pain management (also called pain medicine or algiatry) is a branch of medicine employing an interdisciplinary approach for easing the suffering and improving the quality of life of those living with pain.[1] The typical pain management team includes medical practitioners, clinical psychologists, physiotherapists, occupational therapists, and nurse practitioners.[2] Pain sometimes resolves promptly once the underlying trauma or pathology has healed, and is treated by one practitioner, with drugs such as analgesics and (occasionally) anxiolytics. Effective management of long term pain, however, frequently requires the coordinated efforts of the management team.[3]
Medicine treats injury and pathology to support and speed healing; and treats distressing symptoms such as pain to relieve suffering during treatment and healing. When a painful injury or pathology is resistant to treatment and persists, when pain persists after the injury or pathology has healed, and when medical science cannot identify the cause of pain, the task of medicine is to relieve suffering. Treatment approaches to long term pain include pharmacologic measures, such as analgesics, tricyclic antidepressants and anticonvulsants, interventional procedures, physical therapy, physical exercise, application of ice and/or heat, and psychological measures, such as biofeedback and cognitive behavioral therapy.
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Pain management practitioners come from all fields of medicine. Most often, pain fellowship trained physicians are anesthesiologists, neurologists, physiatrists or psychiatrists. Palliative care doctors are also specialists in pain management. Some practitioners have not been fellowship trained and have opted for certification by the American Board of Pain Medicine which is not recognized by the American Board of Medical Specialties and does not indicate fellowship training. However, the American Board of Anesthesiology and the American Board of Physical Medicine and Rehabilitation have a subspecialty in pain management which is recognized by the American Board of Medical Specialties and does indicate fellowship training. Some practitioners focus more on the pharmacologic management of the patient, while others are very proficient at the interventional management of pain. Interventional procedures - typically used for chronic back pain - include: epidural steroid injections, facet joint injections, neurolytic blocks, spinal cord stimulators and intrathecal drug delivery system implants. Over the last several years the number of interventional procedures done for pain has grown.
As well as medical practitioners, the area of pain management may often benefit from the input of physiotherapists, chiropractors, clinical psychologists and occupational therapists, amongst others. Together the multidisciplinary team can help create a package of care suitable to the patient.
Because of the fast growth in the field of pain medicine many practitioners have entered the field, with many of these practitioners being not board certified or being certified by unrecognized boards.
The World Health Organization (WHO) recommends a pain ladder for managing analgesia. It was first described for use in cancer pain, but it can be used by medical professionals as a general principle when dealing with analgesia for any type of pain.[4] In the treatment of chronic pain, whether due to malignant or benign processes, the three-step WHO Analgesic Ladder provides guidelines for selecting the kind and stepping up the amount of analgesia. The exact medications recommended will vary with the country and the individual treatment center, but the following gives an example of the WHO approach to treating chronic pain with medications. If, at any point, treatment fails to provide adequate pain relief, then the doctor and patient move onto the next step.
Paracetamol (acetaminophen), or a non steroidal anti-inflammatory drug such as ibuprofen.
Paracetamol, an NSAID and/or paracetamol in a combination product with a weak opioid such as hydrocodone, may provide greater relief than their separate use.
When treating moderate to severe pain, the type of the pain, acute or chronic, needs to be considered. The type of pain can result in different medications being prescribed. Certain medications may work better for acute pain, others for chronic pain, and some may work equally well on both. Acute pain medication is for rapid onset of pain such as from an inflicted trauma or to treat post-operative pain. Chronic pain medication is for alleviating long-lasting, ongoing pain.
Morphine is the gold standard to which all narcotics are compared. Fentanyl has the benefit of less histamine release and thus fewer side effects. It can also be administered via transdermal patch which is convenient for chronic pain management. Oxycodone is used across the Americas and Europe for relief of serious chronic pain; its main slow-release formula is known as OxyContin, and short-acting tablets, capsules, syrups and ampules are available making it suitable for acute intractable pain or breakthrough pain. Diamorphine, methadone and buprenorphine are used less frequently. Pethidine, known in North America as meperidine, is not recommended for pain management due to its low potency, short duration of action, and toxicity associated with repeated use. Pentazocine, dextromoramide and dipipanone are also not recommended in new patients except for acute pain where other analgesics are not tolerated or are inappropriate, for pharmacological and misuse-related reasons. Amitriptyline is prescribed for chronic muscular pain in the arms, legs, neck and lower back. While opiates are often used in the management of chronic pain, high doses are associated with an increased risk of opioid overdose.[5]
Opioid medications can provide a short, intermediate or long acting analgesia depending upon the specific properties of the medication and whether it is formulated as an extended release drug. Opioid medications may be administered orally, by injection, via nasal mucosa or oral mucosa, rectally, transdermally, intravenously, epidurally and intrathecally. In chronic pain conditions that are opioid responsive a combination of a long-acting or extended release medication is often prescribed in conjunction with a shorter-acting medication for breakthrough pain, or exacerbations.
Most opioid treatment is oral (tablet, capsule or liquid), but suppositories and skin patches can be prescribed. An opioid injection is rarely needed for patients with chronic pain.
Although opioids are strong analgesics, they do not provide complete analgesia regardless of whether the pain is acute or chronic in origin. Opioids are efficacious analgesics in chronic malignant pain and modestly effective in nonmalignant pain management. However, there are associated adverse effects, especially during the commencement or change in dose. When opioids are used for prolonged periods drug tolerance, chemical dependency, diversion and addiction may occur.[6][7]
Clinical guidelines for prescribing opioids for chronic pain have been issued by the American Pain Society and the American Academy of Pain Medicine. Included in these guidelines is the importance of assessing the patient for the risk of substance abuse, misuse, or addiction; a personal or family history of substance abuse is the strongest predictor of aberrant drug-taking behavior. Physicians who prescribe opioids should integrate this treatment with any psychotherapeutic intervention the patient may be receiving. The guidelines also recommend monitoring not only the pain but also the level of functioning and the achievement of therapeutic goals. The prescribing physician should be suspicious of abuse when a patient reports a reduction in pain but has no accompanying improvement in function or progress in achieving identified goals.[8]
The other major group of analgesics are non-steroidal anti-inflammatory drugs (NSAID). Acetaminophen/paracetamol is not always included in this class of medications. However, acetaminophen may be administered as a single medication or in combination with other analgesics (both NSAIDs and opioids). The alternatively prescribed NSAIDs such as ketoprofen and piroxicam, have limited benefit in chronic pain disorders and with long-term use is associated with significant adverse effects. The use of selective NSAIDs designated as selective COX-2 inhibitors have significant cardiovascular and cerebrovascular risks which have limited their utilization.[9][10]
Some antidepressant and antiepileptic drugs are used in chronic pain management and act primarily within the pain pathways of the central nervous system, though peripheral mechanisms have been attributed as well. These mechanisms vary and in general are more effective in neuropathic pain disorders as well as complex regional pain syndrome.[11] Drugs such as gabapentin have been widely prescribed for the off-label use of pain control. The list of side effects for these classes of drugs are typically much longer than opiate or NSAID treatments for chronic pain, and many antiepileptics cannot be suddenly stopped without the risk of seizure.
Other drugs are often used to help analgesics combat various types of pain and parts of the overall pain experience. In addition to gabapentin, the vast majority of which is used off-label for this purpose, orphenadrine, cyclobenzaprine, trazodone and other drugs with anticholinergic properties are useful in conjunction with opioids for neuropathic pain. Orphenadrine and cyclobenzaprine are also muscle relaxants and are therefore particularly useful in painful musculoskeletal conditions. Clonidine has found use as an analgesic for this same purpose and all of the mentioned drugs potentiate the effects of opioids overall.
Pulsed radiofrequency, neuromodulation, direct introduction of medication and nerve ablation may be used to target either the tissue structures and organ/systems responsible for persistent nociception or the nociceptors from the structures implicated as the source of chronic pain.[12][13][14][15][16]
An intrathecal pump used to deliver very small quantities of medications directly to the spinal fluid. This is similar to epidural infusions used in labour and postoperatively. The major differences are that it is much more common for the drug to be delivered into the spinal fluid (intrathecal) rather than epidurally, and the pump can be fully implanted under the skin. This approach allows a higher dose of the drug to be delivered directly to the site of action, with fewer systemic side effects.[17]
A spinal cord stimulator is an implantable medical device that creates electric impulses and applies them near the dorsal surface of the spinal cord provides a paresthesia ("tingling") sensation that alters the perception of pain by the patient.
Physical medicine and rehabilitation (physiatry/physiotherapy) employs diverse physical techniques such as thermal agents and electrotherapy, as well as therapeutic exercise and behavioral therapy, alone or in tandem with interventional techniques and conventional pharmacotherapy to treat pain, usually as part of an interdisciplinary or multidisciplinary program.[18]
Transcutaneous electrical nerve stimulation has been found to be ineffective for lower back pain, however, it might help with diabetic neuropathy.[19]
Acupuncture involves the insertion and manipulation of needles into specific points on the body to relieve pain or for therapeutic purposes. In 2003, the World Health Organization published an article synthesizing the scientific research (controlled trials) of the time, and concluded acupuncture is helpful for the treatment of pain in some cases of acute pain in the epigastric area, facial pain, headache, knee pain, low back pain, neck pain, pain in dentistry, postoperative pain, renal colic, and sciatica. The authors also concluded acupuncture has demonstrated effectiveness in other conditions for which further proof is needed.[20] This review has been criticized for giving too much weight to low-quality clinical trials, and including a large number of trials originating in China.[21][22] The latter issue is considered problematic because trials originating in the West include a mixture of positive, negative and neutral results while all trials in China are positive (attributed to publication bias rather than fraud).[22] An analysis of the 13 highest quality studies of pain treatment with acupuncture, published in January 2009 in the British Medical Journal, concluded there was little difference in the effect of real, sham and no acupuncture.[23] There is general agreement that acupuncture is of no use even when administered by well-trained practitioners using sterile needles, although further research is appropriate.[24][25][26][27]
A 2007 review concluded low level laser therapy may be effective in reducing inflammation and pain,[28] while a 2008 Cochrane collaboration review concluded that there was insufficient evidence to support the use of LLLT in the management of low back pain.[29]
Mindfulness-based cognitive therapy, the use of stress reduction and relaxation, has been found to reduce chronic pain in some patients.[30][31] Applied behavior analysis views chronic pain as a consequence of both respondent and operant conditioning, where a patient learns to display pain behavior in the presence of specific environmental antecedents and consequences. The model was first proposed by Fordyce in 1976.[32][33] The behavioral model has shown effectiveness in reducing pain responses though operant based interventions.[34] Though cognitive-behavioral intervention can be an effective and economical means of treating chronic pain, the effects are rather modest and a substantial portion of patients gain no benefit.[35]
Biofeedback based on behavioral principles has shown some success for chronic pain, demonstrating greater improvement in one study than peers undergoing cognitive-behavioral therapy and conservative medical treatment,[36] though a different study showed improvements over wait-list controls but no difference between biofeedback and cognitive-behavioral therapy.[37]
A 2007 review of 13 studies found evidence for the efficacy of hypnosis in the reduction of pain in some conditions, though the number of patients enrolled in the studies was small, bringing up issues of power to detect group differences, and most lacked credible controls for placebo and/or expectation. The authors concluded that "although the findings provide support for the general applicability of hypnosis in the treatment of chronic pain, considerably more research will be needed to fully determine the effects of hypnosis for different chronic-pain conditions." (p. 283)[38]
Inadequate treatment of pain is widespread throughout surgical wards, intensive care units, accident and emergency departments, in general practice, in the management of all forms of chronic pain including cancer pain, and in end of life care.[39][40][41][42][43][44][45][46] This neglect is extended to all ages, from neonates to the frail elderly.[47][48][49] In September 2008, the World Health Organization (WHO) estimated that approximately 80 percent of the world population has either no or insufficient access to treatment for moderate to severe pain. Every year tens of millions of people around the world, including around four million cancer patients and 0.8 million HIV/AIDS patients at the end of their lives suffer from such pain without treatment. Yet the medications to treat pain are cheap, safe, effective, generally straightforward to administer, and international law obliges countries to make adequate pain medications available.[50]
Reasons for deficiencies in pain management include cultural, societal, religious, and political attitudes, including acceptance of torture. Moreover, the biomedical model of disease, focused on pathophysiology rather than quality of life, reinforces entrenched attitudes that marginalize pain management as a priority.[51] Other reasons may have to do with inadequate training, personal biases or fear of prescription drug abuse.
In the United States, Hispanic and African Americans are more likely to suffer needlessly in the hands of a physician than whites;[52][53] and women's pain is more likely to be undertreated than men's.[54] It is often recognized that a great number of patients suffering from chronic pain are being under-treated because physicians fail to provide comprehensive pain treatment. This failure may be due to physicians' fear of being accused of over-prescribing (see for instance the case of Dr William Hurwitz), despite the relative rarity of prosecutions (147 cases across USA in 2006), or physicians' poor understanding of the health risks attached to opioid prescription.[50][55][56] As a result of two recent cases in California though, where physicians who failed to provide adequate pain relief were successfully sued for elder abuse, the North American medical and health care communities appear to be undergoing a shift in perspective. The California Medical Board publicly reprimanded the physician in the second case; the federal Center for Medicare and Medicaid Services has declared a willingness to charge with fraud health care providers who accept payment for providing adequate pain relief while failing to do so; and clinical practice guidelines and standards are evolving into clear, unambiguous statements on acceptable pain management, so health care providers, in California at least, can no longer avoid culpability by claiming that poor or no pain relief meets community standards.[56]
Strategies currently applied for improvement in pain management include framing it as an ethical issue; promoting pain management as a legal right, providing constitutional guarantees and statutory regulations that span negligence law, criminal law, and elder abuse; defining pain management as a fundamental human right, categorizing failure to provide pain management as professional misconduct, and issuing guidelines and standards of practice by professional bodies.[51]
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