Pain

Chapter 4 Pain



CHAPTER CONTENTS



Introduction


What is pain?


Origins and classification of pain


Pain sensation


Acute and chronic pain


Psychosocial contributions to pain


Assessment of pain


Medical treatment of pain


Massage and pain management



INTRODUCTION


The common factor in headache and neck pain is pain. The massage therapist must understand pain and use massage methods effectively to manage pain. The massage professional especially needs to understand the mechanisms of pain.


To understand treatment processes that target the pain it is necessary to delve deeper into pain mechanisms and pain management. Pain is a universal experience. The degree to which a person reacts to pain comes from biological, psychological and cultural makeup. Past encounters with painful illness and injury can influence pain sensitivity. People who are prone to recurring illness and injury in the same area can experience increasing pain sensation for the same or even lesser degrees of pathology.


Headache and neck pain are extremely common and the ability to influence the pain symptom is a major aspect of treatment. Massage can be an extremely effective option for pain management, used either as a supportive treatment in conjunction with other treatments as described in Chapter 3, or as a primary treatment method.



WHAT IS PAIN?


Pain is caused by the stimulation of nociceptors. These receptors are usually stimulated by chemicals such as substance P, bradykinin, and histamine, which excite the nerve endings. Pain is elicited by three different classes of stimuli: mechanical, chemical, and thermal. Soft tissue pain is caused by the chemicals released from illness, injury, or from mechanical irritation caused by cumulative stress, microinflammation, or extreme heat or cold. Emotional or psychological stress, called autonomic disturbances, can trigger pain by causing an increase in motor tone of muscles – changes in fascial tone and shifts in fluid flow affecting oxygen and nutrient delivery and waste removal.


Pain of somatic origin and from the viscera sends impulses to the limbic and hypothalamic areas of the brain and may be responsible for emotional reactions of anxiety, fear, anger, and depression. In addition, the brain inhibits or enhances a reaction to pain. This can explain why people can sometimes ignore pain and why fear and anxiety can exaggerate pain. How a person responds to pain is called pain tolerance. How a person interprets the pain sensation increases or decreases tolerance. Intervention that changes perception and meaning of pain can increase tolerance, allowing an individual to have better coping strategies in response to pain stimuli. This is a very important point for how people learn to cope with the chronic pain associated with headaches and neck dysfunction.


Pain receptors are found in almost every tissue of the body and may respond to any type of stimulus. Because of their sensitivity to all stimuli, pain receptors perform a protective function by identifying changes that may endanger the body. When stimuli for other sensations, such as touch, pressure, heat, and cold, reach a certain intensity, they stimulate the sensation of pain as well. Excessive stimulation of a sensory organ causes pain. Additional stimuli for pain receptors include excessive distension or dilation of a structure, prolonged muscular contractions, muscle spasms, inadequate blood flow to tissues, or the presence of certain chemical substances. Pain receptors can become sensitized, which results in fewer stimuli necessary to cause pain sensation.



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Injured tissue may release prostaglandins, making peripheral nociceptors more sensitive to the normal pain response (hyperalgesia). Aspirin and other nonsteroidal anti-inflammatory drugs (often referred to as NSAIDs) inhibit the action of prostaglandins and reduce pain.


The point at which a stimulus is perceived as painful is called the pain threshold. This varies somewhat from individual to individual. One factor affecting the pain threshold is perceptual dominance, in which the pain felt in one area of the body diminishes or obliterates the pain felt in another area. Not until the most severe pain is diminished does the person perceive or acknowledge the other pain. This mechanism is often activated with massage application that produces a ‘good hurt’.


Pain tolerance refers to the length of time or intensity of pain that the person endures before acknowledging it and seeking relief. Unlike the pain threshold, pain tolerance is more likely to vary from one individual to another. A person’s tolerance to pain is influenced by a variety of factors, including personality type, psychological state at the onset of pain, previous experiences, sociocultural background, and the meaning of the pain to that person (e.g., the ways in which it affects the person’s lifestyle). Factors that decrease pain tolerance include repeated exposure to pain, fatigue, sleep deprivation, and stress; warmth, cold, distraction, alcohol consumption, hypnosis, and strong spiritual beliefs or faith all act to increase pain tolerance.



ORIGINS AND CLASSIFICATION OF PAIN


The origins of pain can be divided into two types, somatic and visceral. Somatic pain arises from stimulation of receptors in the skin (superficial somatic pain) or from stimulation of receptors in skeletal muscles, joints, tendons, and fascia (deep somatic pain). Visceral pain results from stimulation of receptors in the viscera (internal organs).


Pain is usually classified as acute, chronic, intractable, phantom, and referred. Pain basically results from a series of exchanges involving three major components: peripheral nerves, spinal cord, and brain.



• Acute pain is an appropriate response to injury or illness. It is easy to control with short-term use of medication, ice, heat, or counterirritants (i.e., medical-based ointments).


• Chronic pain is an inappropriate and ongoing perception of pain. It can be managed with careful use of medication but is best addressed using a multidisciplinary approach supporting lifestyle changes from dependency and side effects.


• Intractable pain is dominant and very hard to control.


• Phantom pain is experienced in an area of amputation.


• Referred pain is when an organ or other tissue projects pain sensation to another area of the body. Trigger point pain is a type of referred pain (Figures 4.1 and 4.2).


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Figure 4.1 Pain referred from viscera. A: Anterior view. B: Posterior view.


(Adapted from Rothstein et al 1991.)


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Figure 4.2 Some common trigger points and their target areas.


(From Chaitow 2003.)



Peripheral nerves


Peripheral nerves encompass a network of nerve fibers that branch throughout the body. Attached to some of these fibers are special nerve endings (nociceptors) that can sense an unpleasant stimulus, such as a cut, burn, or painful pressure.


There are millions of nociceptors in the skin, bones, joints and muscles, and in the protective membranes around the internal organs. Nociceptors are concentrated in areas more prone to injury, such as the fingers and toes. There may be as many as 1300 nociceptors in just 1 square inch of skin. Skin stimulation during massage that is intense enough to stimulate the ‘good hurt’ response causes the nociceptors to fire. This is one of the mechanisms of counterirritation. This is also a major component of massage benefits for pain management.


Muscles, protected beneath the skin, have fewer nerve endings. Internal organs, protected by skin, muscle and bone, have even less. Some nociceptors sense sharp blows, others heat. One type senses pressure, temperature, and chemical changes. Nociceptors can also detect inflammation caused by injury, disease or infection. Massage that addresses these receptors must have enough depth of pressure to elicit a response.


When nociceptors detect a harmful stimulus, they relay their pain messages in the form of electrical impulses along a peripheral nerve to the spinal cord and brain. Sensations of severe pain are transmitted almost instantaneously. Dull, aching pain – such as an upset stomach, earache, or joint aching – is relayed on fibers that transmit at a slower speed.



Spinal cord


When pain messages reach the spinal cord, they meet up with specialized nerve cells that act as gatekeepers, which filter the pain messages on their way to the interpretive areas of the brain where the pain is felt, understood and coping strategies are developed.


For severe pain linked to bodily harm, the ‘gate’ is wide open and the messages take an express route to the brain. Nerve cells in the spinal cord also respond to these urgent warnings by triggering other parts of the nervous system into action, especially the motor nerves, to signal muscles to move away from harm, a process described as a reflex arc. Weak pain messages, however, such as from a scratch, may be filtered or blocked out by the gate entirely.


Within the spinal cord, the messages can also change. Other sensations may overpower and diminish the pain signals. This is called counterirritation or hyperstimulation analgesia. Again, massage is an effective intervention to create counterirritation or hyperstimulation analgesia to suppress pain sensation.


Nerve cells in the spinal cord also release chemicals such as endorphins that diminish or substance P that amplifies the strength of a pain signal that reaches the brain for interpretation. Massage appears to influence these chemical responses, although research has not yet identified the exact mechanism (see Chapter 5).



Brain


When pain messages reach the brain, they are first processed by the thalamus, which is a sorting and switching station. The thalamus quickly interprets the messages as pain and forwards them simultaneously to three specialized regions of the brain: the physical sensation region (somatosensory cortex), the emotional feeling region (limbic system), and the thinking (cognitive) region (frontal cortex). Awareness of pain is therefore a complex experience of sensing, feeling, and thinking. Pain tolerance comes from the interplay of these functions. Massage influences all these areas – somatic sensation through nerve stimulation, limbic system by calming sympathetic dominance and nurturing, and the cognitive areas through education, reframing, and providing symptom relief.


The brain responds to pain by sending messages that trigger the healing process. Signals are sent to the autonomic nervous system, which then sends additional blood and nutrients to the original site of pain transmission.


Pain-suppressing chemicals send ‘stop-pain’ messages. The use of pain-suppressing medication that mimics the body’s own chemicals is controversial and may even slow healing. However, the stress of severe acute pain can slow the healing process and intractable chronic pain suppresses the immune system. In these cases, pain medication is appropriate.



PAIN SENSATION


Pain comes in many forms of physical sensations: sharp, jabbing, throbbing, burning, stinging, tingling, nagging, dull and aching. Pain also varies from mild to severe. Severe pain grabs your attention more quickly and generally produces a greater physical and emotional response than mild pain. Severe pain can be incapacitating, making it difficult or impossible to function.


The location of pain can affect the response to it. A headache that interferes with the ability to focus on work may be more bothersome than, for example, arthritic pain in the ankle. Therefore the headache would receive a stronger pain response.


The emotional and psychological state, memories of past pain experiences, upbringing, and attitude about pain can also affect how people interpret pain messages and tolerate pain.


When pain persists beyond the time expected for healing, pain can become a chronic, nonproductive condition. No longer is the pain just the symptom of another disease, but a separate condition unto itself.



ACUTE AND CHRONIC PAIN


Acute pain is triggered by tissue damage. It is the type of pain that generally accompanies illness and injury, including surgery, and is location specific. Acute pain may be mild and last just a moment, such as from an insect sting, or it can be severe and last for weeks or months, such as from a burn, pulled muscle or broken bone. In a fairly predictable period, and with treatment of the underlying cause, acute pain generally fades away. Massage targets acute pain with symptom management and healing support. It is fairly easy to treat.

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Jun 14, 2016 | Posted by in PAIN MEDICINE | Comments Off on Pain

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