Briefly about pain

Pain types by divisions

• Anatomic pain – may be physiological receptor-functional (protective) or pathological, as a result of local changes.

• Physiological pain – superficial pain, caused by irritation of the skin receptors, mucous membranes and cornea by a damaging factor.

• Pathological pain – caused by chronic irritation of pain receptors by pain mediators released from damaged tissues.

• Deep pain – is pathological, can be caused by blood vessels, bone and joint system, muscles or organ structure.

• Vascular pain – caused by stimulation of mechano- and chemo- pain receptors, located in the outer membrane of large arteries and veins. Stretching of the vascular vessels causes pulsating, tension headaches.

• Bone and joint pain – the source of pain is stimulation of the pain receptors of the joint capsule and periosteum.

• Myalgia – caused by irritation of the receptors in muscles and fascias by accumulated metabolites, when they are over-load and tired.

• Organ pain – include biliary and renal colic.

• Wired pain – arises as a result of direct stimulation of the nerve fibers or pathways. Includes neuralgia, causalgia, radicalgia and phantom pain.

• Neuralgia – applies to the trigeminal nerve, sciatic, femoral and lateral femoral cutaneous nerve.

• Radicalgia – exacerbated by coughing and radiating movements to the appropriate areas of the skin.

• Causalgia – neuralgia with an autonomic component, results from large nerve injuries, with many of the sympathetic nerves. Pains are burning with dystrophic changes – cyanosis, oedema, muscle atrophy

• Convolutional pain – the result of compression on the nerve plexus, caused by cancer or inflammatory changes in the neck, top of the lungs, lower pelvis.

• Phantom pain – occurs in patients after amputation and relates to pain in the amputated limb. Incidence of this pain explains the existence of chronic pain of embedded memory.

Clinical characteristics of pain

In practice, it is easy to inhibit chronic, “slow” pain, using analgesic drugs and difficult to block “sharp”, “fast” pain. Fibres in the dorsal horn, brain stem, and peripheral tissues release neuromodulators, endogenous opioids, that inhibit the action of neurons transmitting the pain impulses. Endorphins are natural opioid-like substances responsible for pain relief. Endorphin levels differ between individuals; therefore, different patients experience pain differently.

This endogenous opioid mechanism may play an important role in the placebo effect. A placebo is an inactive substance or treatment used for comparison with “real” treatment in controlled studies, intended to deceive the recipient and determine the efficacy of the treatment under study. However, despite the lack of any actual value, placebos can also have a surprisingly positive effect on patients. Placebos can and do produce an analgesic response in many patients. There are many reasons why patients might report less pain, and may believe the treatment will change the condition and this belief may produce a subjective perception of a therapeutic effect, causing the patient to feel that their condition has been improved — or that there is an actual improvement in their condition. It has been suggested that placebo effects are created by these and similar cognitive biases.

According to the signal detection theory, the expectation of a treatment creates uncertainty about the sensory information of pain, and the placebo response is a case of perceptual error. There is some evidence that the tendency to use prior expectation when making perceptual decisions, instead of independently evaluating available perceptual information, is a general cognitive style that is positively associated with placebo analgesic responses. Placebo analgesia can affect nociceptive mechanisms in the cortex of the brain and ascending pathways of the spinal cord. It was found that expectations about pain and analgesia can modify pain perception by altering pain mechanisms in the spinal cord. Psychological factors, such as the threat of pain and expectations about analgesia, modify spinal pain transmission, therefore modifying pain.

• Acute pain: duration < 3 months, acts as a warning-defensive (post-operative pain, traumatic, associated with medical procedures).

• Chronic pain: duration > 3 months, does not fulfill the role of warning and defensive, due to the nature and symptoms of the disease is considered in itself, and requires a multi-therapeutic activities.

• Survived pain: most often occurs as a result of improper treatment of acute pain, persists despite the healed tissue, the damage to which resulted in acute pain.

Quality is a feature very useful in evaluation of the origin of pain. Rapid pain suggests neural origin, girdling pain, escalating while coughing, moving indicate core, indicates the root, burning pain, provoked any stimulus indicates neuropathy and nerve damage. Vascular pain is pulsatory, deep pain is dull, sometimes combined with nausea and is derived from organs.

Pain as a social phenomenon

Pain and its aftermath often cause unpleasant consequences for the patient and family. Pain has not only physical and psychological consequences, but also social consequences. Social consequences of pain:

• severe and chronic pain hinder normal functioning and implementing daily duties;

• they lead to the elimination of signs of social activity

• patient focus thoughts on the pain and the constant searching for the cause;

• can cause mental isolation and depression – patient has a sense of dramatically reduced availability of the surrounding world.

• may cause conflicts with family or friends – patient may fall into a depressive mood manifested by sadness, irritability and outbursts of anger.

Pain is more than a physical phenomenon, the psychological, social and spiritual aspects of pain should also be considered. Research suggests that the approach to pain should be multidimensional, Because the assessment of pain, physically expressed pain, psychological state, social and spiritual issues, are individual to a person’s reaction to their pain experience. A comprehensive assessment of pain should consider the following spheres:

• physical effects and symptoms of pain;

• functional effects (interference with activities of daily living);

• psychosocial factors (level of anxiety, mood, fears, factors affecting pain tolerance cultural influences, effects on interpersonal relationships);

• spiritual aspects.

Why should we relieve the pain?

In all patients suffering from chronic pain there are changes related to the physiological and social disorders, affecting the quality of life. They depend mainly on the duration and the intensity of pain, not the cause of the pain. In patients with chronic pain there are common disorders connected with sleep and appetite, decreased libido and sexual activity, psychomotor heaviness and lowered threshold of pain. Sleep disorders are characterized by difficulty with falling asleep because of the patients inability to find a comfortable position, and the pain is then perceived as more annoying. Sleep is restless and interrupted by pain attacks. Many patients after awaking up feel fatigue, and physical and mental exhaustion. Chronic pain also causes changes in behaviour associated with food. The patient often suffers from loss of the appetite and body weight. Some patients feel anxious and an excessive avidity to eat, which with insufficient activity (limited due to pain) may be the cause of obesity, impairing physical activity.

People suffering from chronic pain evince a depressed mood, revealing not only sadness, but also irritability and outbursts of anger. This results in frequent conflicts with family and friends, leads to the gradual elimination of social life, manifestations, psychological isolation, withdrawn, dramatically reduced sense of the world available to patients. Most of the time, patients remain in the supine position, and their thoughts focus on the pain and constant search for the causes and ways to find relief. Most patients are not able to work, their income, standard of living and position in the family are significantly reduced. Patients with strong and chronic pain perceive their situation as hopeless. In desperation, they demand more and more new surgical procedures, seek help from quacks, healers, and demand the prescription of painkillers to l reduce their suffering.

Types of painkillers

• Opioid analgesics. Used to relieve pain of moderate intensity. Drugs belonging to this group are paracetamol and non-steroidal anti-inflammatory drugs – NSAIDs (e.g., aspirin, ibuprofen). Most drugs in this class are available without a prescription, but it is impossible to predict which formulation is the most effective. Side-effects should also be considered, especially in the case of long-term use of this type of medication.

• Opioids. In the treatment of pain, both so-called weak and strong opioids have been applied. Weak opioids (tramadol, dihydrocodeine, codeine) show a trap effect. This means that exceeding the maximum dose will result in side-effects, but does not increase the analgesic activity of the drug. Strong opioids include: morphine, buprenorphine, fentanyl, methadone, oxycodone. Strong opioids do not show a trap effect.

Opioids differ in efficiency, operating time (short-acting, controlled-action), the bioavailability (absorption in the gastrointestinal tract), metabolism, possible use in combination with other drugs, or any kind of side-effect (e.g. constipation, shortness of breath). They limit the psychomotor performance and using them precludes driving a motor vehicle, or operating machinery.

Strategies for pain control

The treatment of chronic pain should be multidirectional. There are pharmacological methods of treatment, physical, rehabilitation, neuromodulation, psychological methods and in some cases, invasive techniques. It is extremely important to ensure mindful and comprehensive care for the patient, and to clarify and obtain acceptance of the chosen method of treatment from the patient.

Pharmacotherapy

Pharmacotherapy should always be selected individually, because what helps one person does not necessarily help another, and may even be harmful. The choice of drug should be based on appropriate diagnosis and currently used analgesic treatment. It is important to take into account possible side-effects which occurred during the previous use of the drugs. It is also important to take into account possible interaction of the proposed drug with other medicines used by patient for other diseases. To obtain an effective pain control, a combination of drugs with different mechanisms of action are used. They are also available in the form of ready-prepared formulations containing a combination of two or more components.

Integrative pain management

Integrative pain management is a treatment approach that uses many types of complementary and alternative medicine such as laser therapy, acupuncture, herbal medicine, thermotherapy (heat), cryotherapy (cold), electrotherapy, psychological and physical therapy (massage, manual technics, kinesiotherapy) to address and resolve pain. These methods – used in an appropriate manner – may improve life and mobility of some patients.

Neuromodulation

Neuromodulating treatments are aimed at stimulating the pain systems. Currently, several neuromodulation methods are used: percutaneous nerve electrostimulation (TENS), peripheral nerve stimulation, acupuncture and vibration. Neuromodulation supports pain treatment methods and by activating the pain inhibitory mechanisms can reduce pain and improve the quality of life patient with chronic pain.

Psychological therapies

Psychological factors have a big influence on the perception of pain, as well as the effectiveness of the treatment. Therefore, all patients with chronic pain should be able to take advantage of professional psychological help, which can affect the emotional aspect of pain. Among the psychological methods that can be effective as a technique supporting the treatment of chronic pain, the most commonly used are: cognitive therapy, behavioural therapy, relaxation techniques and hypnotherapy.

Interventional pain management

Medical physicians use minimally invasive medical procedures to interrupt the nervous system’s transmission of the pain-filled messages from the nerve endings to the brain. In the case of chronic or severe pain, interventional pain management seeks to disrupt the pain cycle. There are many methods: from individual nerves blocks, by intrathecal administration of drugs (e.g. epidural anesthesia during childbirth) to neurodestructive methods (thermolesion, neurolysis) and neurosurgery. Modern medicine offers more and more ways to treat pain. This makes it possible to bring relief to people suffering from various ailments.

Source: Assessment of pain: types, mechanism and treatment, P. Świeboda, R. Filip, A .Prystupa, M. Drozd, Ann Agric Environ Med. 2013; Special Issue 1: 2–7