Chapter 10: Pain and its management.
- Most middle aged people or older people experience chronic pain on a daily basis.
Many people who suffer from chronic feel have more than one chronic health conditions and use
over the counter pain killers, tranquilizers and sleeping pills at rates 2 to 4 times higher than those
without chronic pain. Chronic pain also interferes with people’s normal activity, it also leads to
anxiety and depression.
-Significance of Pain: Pain hurts so it overwhelms other needs, but its significance goes beyond
this disruption. Pain is significant for managing daily activities. Pain is critical to provide us
feedback so we can do something about and see treatment, if there was no pain we wouldn’t
know if there was something wrong and won’t go to seek treatment for it. Minor pains happen to
us all the time which we fix unconsciously such as rolling over sleep etc. However, the
relationship between pain and illness is weak, in example of a cancerous lump which causes no
pain until in its last stages. Pain is what patients fear most in a treatment and it is the reason for
requests for euthanasia.
-Why is pain difficult to study? : Pain is a personal, subjective behavior, influenced by cultural
learning, the meaning and attention paid to the situation and other psychological variables. The
treatment depends on the degree to which it’s felt and how incapacitating it is depends largely on
how it interpreted. Example during world war 2, comparison between wounded soldiers and
wounded civilians, soldiers asked for less morphine than civilians as for soldiers pain meant that
he was alive and will be sent back home where as for a civilian pain meant unwellness and
interruption of valued activities. Cases reported in sports games where when athletes are hurt
remain oblivious to pain b/c of sympathetic arousal to diminish pain sensitivity during sports.
Pain has a cultural component as well; some people have a different reactions and expressions of
pain as other cultures.
-Measuring Pain: Difficulty in treatment of pain is that people have to describe it as it can’t be
seen compared to a lump of cancer or broken bone which can be seen in X-ray. One solution to
measuring pain is the verbal vocabulary that people use to describe pain, such as throbbing pain,
or a dull ache. Some researchers developed pain questionnaires like McGill Pain Questionnaire,
Pain catastrophizing scale etc. Pain behaviors are another measure of pain, four types of pain
behaviors 1) facial and audible expression, 2) distortions in posture or gait, 3) negative affect, 4)
avoidance of activity. Pain behaviors can assess how disrupted one’s life is because of the pain.
-Physiology of Pain: Pain is a protective mechanism that brings into ones awareness of tissue
damage. Pain behavior responses like crying and fear are important in its diagnosis and treatment.
3 types of pain perceptions: 1) nociception results from mechanical damage to the tissue of the
body 2) thermal damage: experience of pain due to temperature 3) polymodal nociception: pain
that triggers chemical reactions from tissue damage.
Nociceptors (peripheral nervers) first sense pain and release chemical messengers which are
conducted down spinal cord to the thalamus, reticular formation and into cerebral cortex which
identify site of injury and send messages back down to spinal column which help block pain.
-Two peripheral nerve fibres: A-delta fibres are small and myelinated that transmit sharp pain
and determine sensory aspects of pain where as C fibres are non myelinated and transmit dull
aching pain and influence motivational and affective elements of pain. Peripheral fibres enter the
spinal column at the dorsal horn. Both fibres project into different brain areas.
- Therioes of Pain: Previously it was believed that amount of pain experienced was
directly proportional to amount of tissue damage but GATE CONTORL THEORY
challenged this by proposing that psychological factors play an important role in
experiencing pain. Acc. To gate control theory, there is neural pain gate which
modulates the pain signals to the brain and which can occur at the spinal column dorsal horn by A-delta fibres which are involved in closing the gate. Signals descending from
the brain can modulate pain thru a central trigger system, of large diameter conducting
fibers that activate cognitive processes which in turn then alter the pain gate thru
descending fibers. Brain could now be seen as selecting, filtering and modulating signals
rather than simply receiving them and dorsal horns as stations that either amplify or
- Pain sensitivity, intensity and duration all interact to influence pain and unpleasantness
and related emotions through a central network of pathway in the limbic structures and
thalamus directs inputs cortex and also carries background input with pain which give the
strong emotions associated with pain! The whole point of this theory is that pain is
different under different circumstance and can be modulated by the brain and that its also
a psychological process!
- Gate control theory misses out Phantom limb pain where a person with an amputated
limb experiences pain in the limb, how does that limb send signals to the brain to
experience pain? This is explained by the neuro-matrix theory!
- The neuro-matrix theory: Acc to this theory, there is a network of neurons that extend
throughout the areas of the brain to create the representation of a physical self, called
body-self neuro-matrix. Neuro-matrix is genetically determined but also by sensory
inputs or experience. Each pain a person experiences, neuro-matrix generates nerve
impulses which are continuously and cyclically processed into a characteristic pattern
called its neurosignature! Each pain has its own neurosignature with a number of
sensory, cognitive and emotional factors that are unique to it and thus in a phantom limb
pain, it is this neurosignature and NOT the sensory inputs that create the pain.
- Neurochemical Bases of Pain and Its Inhibition: The brain can control the amount of
pain a person experiences by send messages to block the transmission of pain. Study
when stimulating a part of a rat’s brain, it produced so much analgesia that the rat
experienced no pain during abdominal surgery.
- Opiates like heroine and morphine are drugs manufactured from plants that help control
pain. Opoids are opiate like substances produced in specific parts of the brain, glands and
project on sites with which have receptors for them.
- 3 types of endogenous opioid peptides:
- 1) beta-endorphins: produce peptides that project on to limbic system and brain stem.
- 2) Proenkephalin: peptides that have widespread neuronal, endocrine and CNS distributn
- 3) Prodynorphins: found in the gut, the posterior pituitary and brain.
- Each of these have different receptors, potencies and profiles.
- These endogenous opioid peptides are pain suppressors of the body and can be effective
in response to stress, and reduce pain called stress-induced analgesia.
- Since they are present in the pituitary gland, hypothalamus further indicates their role in
stress. Also known to have a role in immune function.
- What are the clinical issues in pain management?
Pain is viewed as a disease of its own and has to be managed by health care workers and
physicians by medicines, surgery. Since pain is now believed to be a psychological
component as well, new techniques developed to manage pain such as bio-feedback,
relaxation, hypnosis, acupuncture etc,
- Acute Pain: results from a specific injury that produces tissue damage like broken bone
and disappears with time when tissue damage is repaired.
- Chronic Pain: begins with an acute episode but unlike acute pain doesn’t disappear over
time. Different types of chronic pain: - Chronic benign pain: stays for six months or longer and its stubborn to treatment, varies
in severity. E.g. Chronic low back pain.
- Recurrent acute pain: involves a series of alternating episodes that are acute but stay for
6 months or longer, e.g. migraines.
- Chronic progressive pain: stays for more than 6 months but the severity of the pain
increases over time, malignancies or rheumatoid arthritis, cancer.
- Acute vs. Chronic Pain: Acute and Chronic pains have different psychological profiles
since chronic pain carries a period of psychological distress which complicates diagnosis
- Since pain interferes with daily life activities can lead to depression, most depressed
people have some kind of pain. Also most techniques cure acute pain easier than chronic
pain which requires individualized multiple techniques. Chronic pain involves
physiological, psychological, social and behavioral components that can overtime evolve
into a syndrome.
- Who becomes a Chronic pain patient? The transition from acute pain to chronic pain is
its interference in the person’s daily life activities and its severity. Chronic pain can be
exacerbated by misdiagnoses and inappropriate perceptions and altering one’s posture
and by inadequate coping (not cutting back from home activities and not taking time off
- Chronic pain can entirely disrupt a person’s life; the sufferers have left their jobs,
abandoned their leisure activities, withdrawn from family and friends and evolved an
entire lifestyle about pain and its treatment. Communicate less with family members and