Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 1 of 7)
Pain
Pain Continuum Pain is comprised of both: (a) organic pain (discomfort caused by tissue damage)
(b) psychogenic pain (without physical cause)
Both cause ‘real’ pain and discomfort and usually act together in the same continuum.
However sometimes psychogenic pain can exist alone. Psychological problems
involving chronic bodily complaints are termed somatoform disorders. Pain disorder is
one such somatoform disorder.
Acute/Chronic Acute (a) Occurs over minutes, days and weeks less than 6 months.
(b) Anxiety increases with pain but decreases with improvement
(c) Future recurrence is unassociated with previous occurrence
Chronic (a) Occurs for more than 6 months
(b) Feelings of hopelessness because of failure of treatment
(c) Pain dominates life
Chronic Pain Psychological effects of chronic pain include:
(a) Insomnia
(b) Exhaustion
(c) Irritability
(d) Depression
(e) Preoccupation with pain
Chronic Pain Underlying
Features Examples
Type Cause
Migraine,
Intractable Benign Present all the time
Headache
Repeated intense episodes Chronic Lower
Recurrent Benign
separated by non-pain periods Back Pain
Continuous discomfort Rheumatoid
Progressive Malignant increasing in intensity with Arthritis,
worsening condition Cancer
Pain Without
Physical Basis
Pain
Features
Syndrome
Episodes of extremely painful, recurrent, stabbing pain along the
course of the nerve with no apparent cause. It may be provoked more
Neuralgia
by innocuous stimuli than noxious ones (eg cotton wool rather than a
pin prick)
Pain syndrome of recurrent severe burning pain from a previous
Causalgia
wound such as a gun shot or a stabbing
Occurs in amputees or where the peripheral nervous system is
Phantom
irreparably damaged. Pain is then felt in non-existent limbs or in non-
Limb Pain
functioning nerves. Usually decreases with time.
Pain without physical basis is presumably related to neural damage and involves the
cortical region relating to the homunculus of the area affected. However only some
people experience it.
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 2 of 7)
Pain
Pain Perception Pain is perceived differently according to the context in which the pain occurs. For
example, only 49% of soldiers with certain injuries rated their pain as severe to
moderate compared to 75% of civilians. Of those soldiers only 32% requested
medication compared to 83% of those civilians. The soldiers saw their pain as the end
of war whilst the civilians saw it as the beginning of a personal disaster. (Beecher
1956).
Pain Sensitivity All humans have the same basic pain thresholds. No-one can really be described as
more stoical or more sensitive than another. Tests into pain sensitivity can be
conducted in the lab by various methods including:
(a) Cold Pressor Test (limb immersion in ice water)
(b) Muscle Ischaemia Test (inflation of cuff)
(c) Electric Shock or Trans-Cutaneous Electrical Nerve Stimulation (TENS)
Learning & Pain Pain is associated with antecedents. For instance migraine sufferers may experience
nausea or dizziness and this may lead to a conditioned response to the antecedent
stimulus. Words and concepts describing pain can also become conditioned stimuli to
pain (Jamner & Tursky 1987).
Pain Behaviour Behaviours on experiencing pain can include:
(a) Facial/audible expression of pain
(b) Distorted ambulation/posture and guarding
(c) Negative affect (mood)
(d) Decreased activity
Pain behaviour is part of the ‘sick role’ and is often maintained by operant
conditioning. The pain behaviour could become entrenched in chronic pain with the
feeling of powerlessness over the pain. In addition secondary gains may be made
such as not doing the housework or disability payments which prolong the pain.
Social Support Social processes during episodes of pain are important. Care and concern are
important but must be used alongside encouragement to increase activity and
decrease powerlessness. Attention, affection and care without these things can lead
to reinforcement of the pain behaviour (Gil et al 1988, Flor et al 1987). Decreased
activity can lead to physical deterioration and increased pain. A vicious cycle can
evolve.
Sick Role
Pain Behaviour Solicitousness
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 3 of 7)
Pain
Sociological Pain behaviour is influenced by sociological factors such as:
Factors (a) Gender Women report more migraine, men report more headaches
(b) Cultural Black Americans report more dental pain than others
Emotion & Pain and emotion are intimately linked by cognitive processes. Chronic pain is often
Coping accompanied by anger, fear and sadness. Kent (1985) and Cooper (1987) have both
showed direct effects of anxiety on pain. Gannon et al (1987) have shown that stress
is directly related to muscle contraction headache. Stress is also caused as a result of
pain. Pain in chronic sufferers is rated as the most stressful factor in their lives. It is
compounded by feelings of having no control.
Spontaneous coping practices include:
(a) Hoping/Praying
(b) Being brave
(c) Diverting attention away from pain
As a result of strong emotions chronic pain sufferers are more likely to suffer from the
following than the general population:
(a) Depression
(b) Hypochondriasis (preoccupation with health and symptoms)
(c) Hysteria (tendency to cope by developing physical symptoms or denial)
Psychological
Treatment
Treatment
Features
Option
Substantial relief in half of patients with pain compared to real drugs
although effectiveness declines with repeated use. It may be related
Placebos
to the Central Gate Theory of pain (Levin et al 1978) releasing
endogenous opioids from the brain.
Involves the extinction of pain behaviours (which are ignored) and
Behavioural the reinforcement of well behaviour (by praise or reward) and is
(Operant) applied when other attempts have failed, to reduce reliance on
medication or to reduce accompanying disability.
These work by reducing stress and are established treatments for
Relaxation & headaches (Holroyd & Penzien 1985) and require weekly sessions
Biofeedback for 2-3 months. Two techniques are Progressive Muscle Relaxtion
or Biofeedback via EMG or temperature.
This method works by using distraction on an external stimulus or
non-pain imagery to alleviate symptoms, pain redefinition
Cognitive
challenging the patient’s thoughts, hypnosis or insight therapy which
is useful in establishing sociocognitive reasons for pain
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 4 of 7)
Pain
Reasons for Pain exists for a number of reasons. These reasons include:
Pain (a) Recognition of self
(b) Protection from trauma
(c) Reduction of trauma
(d) Warning sign of illness
(e) Warning sign of infection
Absence of Pain can be absent for a number of reasons but usually as a result of nerve damage.
Pain It can also be absent due to congenital insensitivity. Causes of absence of pain
include: (a) Diabetes
(b) Stroke
(c) Trauma
(d) Syphilis
(e) Leprosy
Neurobiology The neurobiology of pain is a complex system and is not hardwired. Long-term
changes can occur in the CNS and PNS following a noxious stimulus.
Inflammation
Sympathetic
Tissue Damage
Terminals
Sensitising Soup
Nerve Growth Factor H+ ions Norepinephrine K+ ions
Neuropeptides Purines Prostaglandin Serotonin
Leukotrienes Bradykinin Histamine Cytokines
Transduction
Sensitivity
High Threshold Low Threshold
Nociceptors Nociceptors
Nociception
Pathway
Assessment Pain can be assessed by asking the patient to score themselves on various scales:
of Pain (a) Visual Analogue Scale (10cm line without markings)
(b) Personality Inventories (for chronic pain – personality and stress markers)
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 5 of 7)
Pain
Drug Different levels of drug treatment can be offered for pain. These include:
Treatment (a) Systemic analgesia
(b) Regional analgesia
(c) Regional opioid analgesia
(d) Other drugs
(e) Other techniques (TENS, acupuncture)
Analgesia The ‘pain ladder’ involves assessing the level of pain and using appropriate drugs for
that level of pain.
Paracetamol
Minor Pain
Aspirin
Coproxamol (paracetamol + propoxifine)
Codydramol (paracetamol + codeine)
Moderate Pain
Pethidine
Tramadol
Severe Pain Opioids (eg Morphine)
Surgical The pain of surgery can be dealt with a number of ways. The following table details
Analgesia the main methods used.
(a) Nerve blocks/regional anaesthesia
Pre-emptive (b) Pre-medication with opioids
Analgesia (c) Supplementary agents (α2 agonists)
(d) Alternatives (hypnosis, acupuncture)
(a) Lignocaine
Local
(b) Bupivacaine
Anaesthesia
(c) Prilocaine
Sodium Channel Sodium channel blockers prevent sensory
Blocker and motor fibre conduction
(a) Topical
(b) Local
Regional (c) IV
Anaesthesia (d) Plexus/sheath
(e) Epidural
(f) Spinal (intrathecal)
(a) Opioids
Combination (b) Steroids
(c) Guanethidine
Opioids Opioids are generally the most potent of all pain-killing drugs and can be classified
according to strength.
Propoxifine
Minor Codeine
Tramadol
Intermediate Buprenorphine
Morphine
Diamorphine (Heroin)
Oxycodone
Major Fentanil
Sufentanil
Alfentanil
Remifentanil
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 6 of 7)
Pain
Opioid During episodes of acute pain the dose should be whatever is required. Initially a
Administration loading dose should be administered and subsequent doses added according to
need. Care should be taken in titration and dosage taking into account the half-life of
the opioid and patient’s body mass.
Administration can be by various means:
(a) Intravenous
(b) Intramuscular
(c) Infusion
(d) Regional (inc spinal)
(e) Combination (with NSAIDs, local anaesthesia etc)
NSAIDs Inflammatory pain can be treated using non-steroidal anti-inflammatory drugs
(NSAIDs) such as aspirin or ibuprofen. These inhibit the cyclo-oxygenase pathways
(COX). There are two COX enzymes, COX1 and COX2 – COX1 is always present
whilst COX2 in only induced by inflammation. Both can be neurotransmitters and
NSAIDs can therefore have central effects as well as peripheral ones.
Chronic Pain Options for the treatment of chronic pain include:
Treatment (a) Multiple Modality Pain Clinic (Holistic)
(b) Drugs
(c) Nerve Blocks
(d) TENS
(e) Acupuncture
(e) Physiotherapy
(f) Occupational Therapy
(g) Psychology
Neuropathic Options for the treatment of neuropathic pain include:
Treatment (a) TCA anti-depressants (esp amitryptilline)
(b) Anticonvulsants (carbamazepine, sodium valproate, clonazepam)
(c) Clonidine
(d) Opioids
(e) Local anaesthetic
(f) Anti-arrhythmias
Paediatric Pain Paediatric pain is similar to adult pain, but is a specialised area of clinical practice
which requires greater use of psychology and may require ongoing treatment for
many years.
Elderly Pain After the age of 70 there broader inter-individual variability and there is less ability for
the clinician to generalise to set regimes. There is a much wider spectrum of organ
and tissue function in these individuals. The main problems are:
(a) Changed body composition.
(b) Changed physiology.
(c) Changed pharmacokinetics and pharmacodynamics
(d) Difficult diagnosis due to communication difficulties arising from differing
terminology, a more stoical approach by the elderly, reduced attention span
and dementia or confusion.
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Nem’s Notes… Phase 2 Year 3
NEUROSCIENCE 5 (page 7 of 7)
Pain
Complex Pain There are three main areas where pain is complex and requires a specialist approach.
Syndromes These are: (a) Sickle cell disease (SEE Blood and Lymph 2)
(b) HIV and AIDS
(c) Cancer
HIV/AIDS and Cancer pain may actually be several different pains, both acute and
chronic in nature. These may include:
(a) Nociceptive/Neuropathic pain
(b) Related pains (eg bedsores)
(c) Treatment related (eg scarring)
(d) Concurrent problems (eg arthritis)
Model of Suffering
Pain
Other Symptoms
Psychological Distress
Spiritual/Existential Distress Perception and Expression of
Family Distress Appraisal of Pain Suffering
Social Distress
Financial Needs
Healthcare Concerns
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