Transcript PATHOPHYSIOLOGY OF PAIN

PATHOPHYSIOLOGY OF PAIN
Lecture of the
Neurology Course
Content of lecture
• Definition of pain
• Physiology – pathways and centers
• Types of pain
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Definitions of pain
• Pain is a complex unpleasant phenomenon
composed of sensory experiences that include
time, space, intensity, emotion, cognition, and
motivation (WHO´s definition)
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The experience of pain
Three systems interact usually to deal with
pain:
1. Sensory
2. Motivational
3. Cognitive
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Pain categories due to the onset: Acute pain
Responses to acute pain
- increased heart rate
-  gastric acid secretion
viscera,
- increased respiratory rate
-  gastric motility
-  glycaemia
nausea occasionally
Psychological and behavioural responses :
- fear
- general unpleasant sense
- elevated blood pressure
-  blood flow to the
kidney and skin
- pallor or flushing, dilated pupils
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- anxiety
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Pain categories due to the onset: Chronic pain
Chronic pain produces significant behavioural and psychological changes:
- depression
- an attempt to avoid pain –minimize deteriorating behaviour
- sleeping disorders
- tendency to deny pain
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Pain threshold and pain tolerance
pain threshold is the point at which a stimulus is perceived as pain
pain tolerance is expressed as duration of time or the intensity of pain that an individual will
endure before pain response initiates.
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Neuroanatomy of pain
The parts of the nervous system responsible for the sensation and perception :
1. afferent pathways
2. CNS
3. efferent pathways
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Sensory input is influenced by neuromodulators
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Substance P
Calcitonin gene related peptide
Serotonin
Norepinepherine
Opiates
a. Exogenous opiates (narcotics)
b. Endogenous opiates
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Pain theories
Cousins’ theory of pathophysiology of acute pain
Selye’s theory of stress and General adaptation syndrome
Neuman systems model
Gate control theory (created by Melzack and Wall 1965)
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Pain categories due to the origin
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Nociceptive pain
Neuropathic pain
Referred pain
Sensitisation
Allodynia
Deaferentation pain
Muscle
Visceral Pain
Neuralgia
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General assessments and treatment of pain
Patient’s verbalization and description of pain
Duration of pain
Location of pain
Quantity and intensity of pain
Quality of pain
Chronology of pain
Aggravating and alleviating factors
Behavioral responses
Effect of pain on activities and lifestyle
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