pain and pain pathway

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Presented by:
Dr. Shermil Sayd

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3. • Introduction
• Definition
• History
• Incidence
• Related Terms
• Characteristics of pain
• Classification
• Pain receptors
• Neural pain pathways
• Sensory neurons
• Peripheral mechanism of injury induced pain
• Theories of pain
• Pain pathways
Dual pain pathway
Pain pathway of Maxillofacial Region
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4. • Modulation of pain
• Factors affecting pain
• Visceral pain
• Referred pain
• Phantom limb pain
• Inhibition of pain
• Diagnosis
• Treatment
• Conclusion
• References 4

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8. DEFINITION OF PAIN
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13. CHARECTERISTICS OF PAIN
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15. PAIN
Somatic
(somasthetic)
Visceral (from viscera)
e.g. angina
pectoris, peptic
ulcer, intestinal
colic, renal colic, etc.
Superficial (from skin &
subcutaneous tissue) e.g.
superficial cuts/burns, etc.
Deep (from
muscles/bones/fascia/periosteum)
e.g.
fractures/arthritis/fibrositis, ruptur
e of muscle belly
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16. • Fast pain within 0.1 sec
• Slow pain after 1 sec or more : Associated with tissue destruction
PRACTICAL CLINICAL CLASSIFICATION OF CRANIO -
FACIAL PAIN
General
Classification
Origin of Pain Quality of Pain
Extra cranial
Structure
Craniofacial region Varies
Referred pain from
remote pathologic
sites
Distant organs and
structures
Aching and
pressing
Intracranial
pathosis
Brain and related
structures
Varies
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17. Neurovascular Blood Vessels Throbbing,
pulsing or
pounding
Neuropathic Sensory nervous
system
Shooting, sharp,
burning pain
Causalgic Sympathetic
nervous system
Burning
Muscular Muscles Deep aching, tight
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18. It can be also classified as :-
Typical Pain Disorders Atypical Pain Disorders
Periodontalgia
Neuralgic (trigeminal neuralgia)
Vascular (migraine, cluster
headache)
Otic (Otitis media)
Sinus (Sinusitis)
Heart (cariogenic jaw pain)
Salivary gland Disorder
Musculo skeletal disorder
Causalgia
Reflex sympathetic dystrophy
Atypical facial pain
Phantom tooth pain
Neuralgia including
cavitational osteonecrosis
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21. SENSORY RECEPTORS
GENERAL
SENSES
SPECIAL
SOMATIC VISCERAL
SUPERFICIAL DEEP
Touch-pressure
Thermal
Pain
Pain
Proprioception
Pain
Baroreception
Chemoreception
Visual
Audition
Olfaction
Gustation
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23. NOCICEPTORS
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31. Aß - fibres Aδ - fibres C- fibres
Threshold Low Medium High
Axon diameter 6-14μm 1-6μm 0.2-1μm
Myelination Yes Thinly No
Velocity 36-90 5-36 0.2-1
Receptor types Mechanoreceptor Mechano/Nocice
ptor
Nociceptor
Receptive field Small Small Large
Quality Touch Sharp/first pain Dull/second pain
Summary of receptor types
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35. SENSORY NEURONS
First Order Second Order Third Order
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89. Dermatome Rule
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107. Diagnosis based on specific questions and tests
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NEUROPATHIC PAIN

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PAIN PATHWAYS AND MEDICATIONS
Pain Pathways Medications
Peripherally (at the nociceptor) Cannabinoids, NSAIDs, Opioids, Tramadol,
Vanilloid receptor antagonists (i.e., capsaicin)
Peripherally
(along the nociceptive nerve)
Local anaesthetics, Anticonvulsants (except
the gabapentinoids)
Centrally
(various parts of the brain)
Acetaminophen, Anticonvulsants (except the
gabapentinoids), Cannabinoids, Opioids,
Tramadol
Descending inhibitory pathway
in the spinal cord
Cannabinoids, Opioids, Tramadol, Tricyclic
antidepressants, SNRIs
Dorsal horn of the spinal cord Anticonvulsants, Cannabinoids,
Gabapentinoids, NMDA receptor
antagonists, Opioids, Tramadol, Tricyclic
antidepressants, SNRIs

147. • Pain is bad, but not feeling pain can be worse.
• Individuals with a congenital absence of pain receptors are
extremely rare but not unknown. Such individuals are very poor
at avoiding accidental injuries, and often inflict mutilating
injuries on themselves.
• As a result, their life span is usually short. thus pain, although
unpleasant, is a protective sensation with enormous survival
value. Pain is a multidimensional experience involving both the
sensation evolved by noxious stimuli but also the relation to it.
• The sensation of pain therefore depends in part on the patient
past experience, personality and level of anxiety.
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148. • Every day patient seeks care for the reduction or
elimination of pain.
• Nothing is more satisfying to the clinician than the
successful elimination of pain.
• The most important part of managing pain is
understanding the problem and cause of pain.
• It is only through proper diagnosis that appropriate
therapy can be selected.
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150. 1. Bell`s „Orofacial pain‟, 5th edition, Jeffrey P. Okeson.
2. Text book of Medical Physiology, 2nd edition, Chaudhari.
3. Text book of Medical Physiology, 10th edition, Arther C Gyton.
4. Dental Clinics of North America 1978: 22 (1); 1-61.
5. Text book of „Oral medicine‟- 10th edition, Burkett‟s.
6. Gray's Anatomy – 38th Edition, Churchill Eivingstone.
7. Understanding “Medical physiology”- 3rd edition, R L Bijlani.
8. Core Topics in Pain – Anita Holdcroft, Sian Jagger.
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9. Pain – Wikipedia, the free encyclopedia
10. Rolf-Detlef Treede. Neurophysiological studies of pain pathways in
peripheral and central nervous system disorders. J Neurol (2003) 250 :
1152–1161.
11. Ascending Sensory Pathways, Chapter 10.
12. Pain pathway & Medications – Painexplained.ca, The Canadian Pain
Society.

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