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4/5/2014
4/5/2014
‘PATHWAY OF PAIN’
ORAL BIOLOGY
PRESENTATION
4/5/2014
PRESENTED BY:
DR.TEHRIM NASEER
4/5/2014
4/5/2014
‘PAIN’
An unpleasant sensory and emotional
experience which we primarily associate with
tissue damage or describe...
4/5/2014
4/5/2014
4/5/2014
‘NOCICEPTION’
The detection of tissue damage by
specialized transducers connected to A-
delta and C-fibers.
4/5/2014
CHARACTERISTICS OF
PRIMARY
AFFERENT FIBRES
A-DELTA FIBER:
• Myelinated
• Diameter fine 2 - 5 μm
• 12 - 30 m/sec. ...
4/5/2014
CHARACTERISTICS OF PRIMARY
AFFERENT FIBRES
C-FIBER:
• Non-Myelinated
• Diameter less than 2 films
• -0.5 to 2 m/s...
4/5/2014
CLASSIFICATION OF PAIN NOCICEPTION
• Proportionate to the stimulation of the nociceptor.
• When acute
•Physiologi...
4/5/2014
‘CLASSIFICATION OF PAIN’
4/5/2014
NEUROPATHIC PAIN:
• Sustained by aberrant processes in
PNS or CNS
• Disproportionate to the stimulation of
nocice...
4/5/2014
MIXED PAIN:
• Nociceptive components
• Neuropathic components
• Examples:
• Failed low-back-surgery syndrome
• Co...
4/5/2014
IDIOPATHIC PAIN:
• No underlying lesion found yet, despite
investigation
• Pain disproportionate to the degree of...
4/5/2014
‘NORMAL CENTRAL PAIN
MECHANISMS’
4/5/2014
Ascending Tracts Descending Tracts
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
THALAMUS
4/5/2014
‘ASCENDING AND DESCENDING PAIN
PATHWAYS’
4/5/2014
4/5/2014
4/5/2014
‘PAIN INHIBITORY AND PAIN
FACILITATORY MECHANISMS
WITHIN DORSAL HORN’
4/5/2014
DORSAL HORN GATING MECHANISM
4/5/2014
Neuronal circuitry within the dorsal horn.
Primary afferent neuron axons synapse onto
spinothalmic neurons and on...
4/5/2014
4/5/2014
‘FACIAL PAIN’
4/5/2014
CAUSES OF FACIAL PAIN
4/5/2014
CAUSES OF FACIAL
PAIN
Facial pain can be caused by anything, from an infection to nerve damage in the face.
Commo...
4/5/2014
More serious causes for facial pain include:
• herpes zoster (shingles)
• migraine
• sinusitis (sinus infection)
...
4/5/2014
CHRONIC OROFACIAL
PAIN
4/5/2014
TRIGEMINAL
NEURALGIA
4/5/2014
4/5/2014
TRIGEMINAL
NEURALGIA
• Tic douloureux / fothergill’s neuralgia
• Paroxysms of fleeting ,excruciating u/l facial p...
4/5/2014
4/5/2014
• Trigeminal / gasserian / semilunar ganglion
• Situated just beside pons in a shallow
depression in petrous apex...
4/5/2014
• Fibres – pain & temp – enter spinal tract of
trigeminal & descend to various levels
depending on their somatotr...
4/5/2014
4/5/2014
• B/L Weakness of
muscles of
mastication with
inability to close the
mouth ( dangling
jaw ) – motor neuron
ds, ne...
4/5/2014
Clinical examination
SENSORY FUNCTIONS
• Pain, touch, heat, cold – tested on face &
mucous membranes
• Each of th...
4/5/2014
Stimulate Direct
corneal
reflex
Consensual
corneal
reflex
Complete
VthN
lesion
Involved eye Absent Absent
Opposit...
4/5/2014
4/5/2014
Second-Order Neuron; Some times is called a
transmission neuron since it transfer the
impulse on to higher center...
4/5/2014
Afferent (Sensory) Somatic
Nerves
• – Trigeminal Nerve
• – Facial Nerve
• – Glossopharyngeal Nerve
• – Vagus Nerv...
4/5/2014
Efferent (Motor) Somatic
Nerves
– Occulomotor, and abducent Nerves
– Trigeminal Nerve
– Facial Nerve
– Glossophar...
4/5/2014
TYPES OF PAIN
• Myofascial Pain
• Myositis
• Myospasm and Dystonia
• Protective Muscle Splinting
• Contracture
• ...
4/5/2014
LEISIONS AND
DISORDERS OF
NERVES
4/5/2014
Supranuclear lesions
• Lesions affecting corticobular pathway -
Contralateral trigeminal motor paresis
(deviation...
4/5/2014
NUCLEAR LEISIONS
• Motor , sensory nuclei – primary/met .
tumours
AV malformations
demyelinating ds
infarction/h’...
4/5/2014
Lesions affecting preganglionic
trigeminal nerve roots
• Tumour ( meningioma, schwannoma, metastasis,
nasopharyng...
4/5/2014
HERPES ZOSTER
4/5/2014
Lesions affecting peripheral branches
of VthCranial Nerve
• Ophthalmic div : in middle cranial fossa , at
tempora...
4/5/2014
Raeder’s paratrigeminal
syndrome
• U/l oculosympathetic paresis – miosis ,
ptosis (without facial anhydrosis)
• E...
4/5/2014
Lesions affecting Gasserian ganglion
• Lesions of middle cranial fossa ( tumour, herpes zoster, sarcoidosis,
syph...
4/5/2014
‘VISCERAL PAIN’
4/5/2014
4/5/2014
VISCERAL PAIN PATHWAY
Pain - Aδ and fibers
Travel with autonomic afferent
Spinal cord
(Dorsal Horn)
Lat. spinotha...
4/5/2014
4/5/2014
4/5/2014
‘REFERENCES’
• Guyton and Hall textbook of Medical Physiology
• http://science.howstuffworks.com/life/inside-the-...
4/5/2014
4/5/2014
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Pathway of Pain

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Pathway of Pain

  1. 1. 4/5/2014
  2. 2. 4/5/2014 ‘PATHWAY OF PAIN’ ORAL BIOLOGY PRESENTATION
  3. 3. 4/5/2014 PRESENTED BY: DR.TEHRIM NASEER
  4. 4. 4/5/2014
  5. 5. 4/5/2014 ‘PAIN’ An unpleasant sensory and emotional experience which we primarily associate with tissue damage or describe in terms of such damage, or both.
  6. 6. 4/5/2014
  7. 7. 4/5/2014
  8. 8. 4/5/2014 ‘NOCICEPTION’ The detection of tissue damage by specialized transducers connected to A- delta and C-fibers.
  9. 9. 4/5/2014 CHARACTERISTICS OF PRIMARY AFFERENT FIBRES A-DELTA FIBER: • Myelinated • Diameter fine 2 - 5 μm • 12 - 30 m/sec. conduction velocity • Terminated at I and V layer • Fast pain, rapid, pricking and well localized • Neurotransmitter - Glutamate • 20% pain conduction
  10. 10. 4/5/2014 CHARACTERISTICS OF PRIMARY AFFERENT FIBRES C-FIBER: • Non-Myelinated • Diameter less than 2 films • -0.5 to 2 m/s conduction velocity • Terminate in I and n layers • Slow, diffuse, dull, aching
  11. 11. 4/5/2014 CLASSIFICATION OF PAIN NOCICEPTION • Proportionate to the stimulation of the nociceptor. • When acute •Physiologic pain •Serves a protective function •Normal pain • when chronic •Pathologic pain
  12. 12. 4/5/2014 ‘CLASSIFICATION OF PAIN’
  13. 13. 4/5/2014 NEUROPATHIC PAIN: • Sustained by aberrant processes in PNS or CNS • Disproportionate to the stimulation of nociceptor • Serves no protective function • Pathologic pain
  14. 14. 4/5/2014 MIXED PAIN: • Nociceptive components • Neuropathic components • Examples: • Failed low-back-surgery syndrome • Complex regional pain syndrome
  15. 15. 4/5/2014 IDIOPATHIC PAIN: • No underlying lesion found yet, despite investigation • Pain disproportionate to the degree of clinically discernible tissue injury
  16. 16. 4/5/2014 ‘NORMAL CENTRAL PAIN MECHANISMS’
  17. 17. 4/5/2014 Ascending Tracts Descending Tracts CORTEX MIDBRAIN PONS MEDULLA SPINAL CORD THALAMUS
  18. 18. 4/5/2014 ‘ASCENDING AND DESCENDING PAIN PATHWAYS’
  19. 19. 4/5/2014
  20. 20. 4/5/2014
  21. 21. 4/5/2014 ‘PAIN INHIBITORY AND PAIN FACILITATORY MECHANISMS WITHIN DORSAL HORN’
  22. 22. 4/5/2014 DORSAL HORN GATING MECHANISM
  23. 23. 4/5/2014 Neuronal circuitry within the dorsal horn. Primary afferent neuron axons synapse onto spinothalmic neurons and onto inhibitory and excitatory neurons.
  24. 24. 4/5/2014
  25. 25. 4/5/2014 ‘FACIAL PAIN’
  26. 26. 4/5/2014 CAUSES OF FACIAL PAIN
  27. 27. 4/5/2014 CAUSES OF FACIAL PAIN Facial pain can be caused by anything, from an infection to nerve damage in the face. Common causes for facial pain include: • oral infections • ulcers (open sores) • abscess (collection of pus under the surface tissue in the mouth, for example) • skin abscess (collection of pus under the skin) • headache • facial injury • toothache
  28. 28. 4/5/2014 More serious causes for facial pain include: • herpes zoster (shingles) • migraine • sinusitis (sinus infection) • nerve disorder
  29. 29. 4/5/2014 CHRONIC OROFACIAL PAIN
  30. 30. 4/5/2014 TRIGEMINAL NEURALGIA
  31. 31. 4/5/2014
  32. 32. 4/5/2014 TRIGEMINAL NEURALGIA • Tic douloureux / fothergill’s neuralgia • Paroxysms of fleeting ,excruciating u/l facial pain, usually lasting less than a minute. • Usually V2/V3 , rarely V1 • MC – adv age, women , rt side • Stimulation of trigger zone – pain • Pain – by activities like talking, chewing, brushing teeth, exposure to cold, by wind on face
  33. 33. 4/5/2014
  34. 34. 4/5/2014 • Trigeminal / gasserian / semilunar ganglion • Situated just beside pons in a shallow depression in petrous apex – meckel’s cave • Sensory root enters the pons course dorsomedially & terminate within brainstem: Nucleus of spinal tract of Vth N Main/Principal sensory nucleus Mesencephalic nucleus
  35. 35. 4/5/2014 • Fibres – pain & temp – enter spinal tract of trigeminal & descend to various levels depending on their somatotropic origin, then synapse in adjacent nucleus of spinal tract. • The axons of second order neurons cross midline, aggregate as trigeminothalamic tract & ascend to VPM • From VPM , fibres project through thalamic radiations to sensory cortex in post central gyrus
  36. 36. 4/5/2014
  37. 37. 4/5/2014 • B/L Weakness of muscles of mastication with inability to close the mouth ( dangling jaw ) – motor neuron ds, neuromuscular transmission disorder, myopathy Clinical examination motor functions
  38. 38. 4/5/2014 Clinical examination SENSORY FUNCTIONS • Pain, touch, heat, cold – tested on face & mucous membranes • Each of the 3 divisions of Vth.N is tested individually and compared with the opposite side.
  39. 39. 4/5/2014 Stimulate Direct corneal reflex Consensual corneal reflex Complete VthN lesion Involved eye Absent Absent Opposite eye Normal Normal Complete VIIthN lesion Involved eye Absent Normal Opposite eye Normal Absent
  40. 40. 4/5/2014
  41. 41. 4/5/2014 Second-Order Neuron; Some times is called a transmission neuron since it transfer the impulse on to higher center . The synapse of the primary afferent and second-order neuron occurs in the dorsal horn of the spinal cord .
  42. 42. 4/5/2014 Afferent (Sensory) Somatic Nerves • – Trigeminal Nerve • – Facial Nerve • – Glossopharyngeal Nerve • – Vagus Nerve • – Cervical Spinal Nerves
  43. 43. 4/5/2014 Efferent (Motor) Somatic Nerves – Occulomotor, and abducent Nerves – Trigeminal Nerve – Facial Nerve – Glossopharyngeal nerve
  44. 44. 4/5/2014 TYPES OF PAIN • Myofascial Pain • Myositis • Myospasm and Dystonia • Protective Muscle Splinting • Contracture • Neoplasia • Fibromyalgia
  45. 45. 4/5/2014 LEISIONS AND DISORDERS OF NERVES
  46. 46. 4/5/2014 Supranuclear lesions • Lesions affecting corticobular pathway - Contralateral trigeminal motor paresis (deviation of jaw away from the lesion) • B/L UMN lesions ( pseudobulbar palsy ) – trigeminal motor paresis , exaggerated jaw jerk.Mastication markedly impaired. • Thalamic lesions – anaesthesia of c/l face • Parietal lesions – depression of c/l corneal reflex
  47. 47. 4/5/2014 NUCLEAR LEISIONS • Motor , sensory nuclei – primary/met . tumours AV malformations demyelinating ds infarction/h’age syringobulbia that affect pons, medulla and upper cervical cord.
  48. 48. 4/5/2014 Lesions affecting preganglionic trigeminal nerve roots • Tumour ( meningioma, schwannoma, metastasis, nasopharyngeal ca ) • Infection ( granulomatous, infectious , carcinomatous meningitis ) • Trauma • Aneurysm Char i/p facial pain, parasthesias, numbness, sensory loss, corneal reflex depressed, trigeminal motor paresis.
  49. 49. 4/5/2014 HERPES ZOSTER
  50. 50. 4/5/2014 Lesions affecting peripheral branches of VthCranial Nerve • Ophthalmic div : in middle cranial fossa , at temporal bone apex, lat wall of cavernous sinus, sup.orbital fissure, distally in face • Maxillary div : lower lateral wall of cavernous sinus, at foramen rotundum, in pterygopalatine fossa, in floor of orbit, at infraorbital foramen, in face
  51. 51. 4/5/2014 Raeder’s paratrigeminal syndrome • U/l oculosympathetic paresis – miosis , ptosis (without facial anhydrosis) • Evidence of trigeminal involvement on same side. • d/t lesions in middle cranial fossa ( b/w trigeminal ganglion & int.carotid.a, near petrous apex) • Lesions of gasserain ganglion – tumour, aneurysm, trauma, infection
  52. 52. 4/5/2014 Lesions affecting Gasserian ganglion • Lesions of middle cranial fossa ( tumour, herpes zoster, sarcoidosis, syphilis, tuberculosis, arachnoiditis, trauma, abscess ) • Pain – severe & paroxysmal • Hemifacial / selective div of Vth CN ( esp V2,V3 )  Parasthesias , numbness may also occur  Sensory loss depends on div involved  u/l pterygoid & masseter paresis may occur.
  53. 53. 4/5/2014 ‘VISCERAL PAIN’
  54. 54. 4/5/2014
  55. 55. 4/5/2014 VISCERAL PAIN PATHWAY Pain - Aδ and fibers Travel with autonomic afferent Spinal cord (Dorsal Horn) Lat. spinothalmic tract Thalamus Somatosensory Cortex
  56. 56. 4/5/2014
  57. 57. 4/5/2014
  58. 58. 4/5/2014 ‘REFERENCES’ • Guyton and Hall textbook of Medical Physiology • http://science.howstuffworks.com/life/inside-the-mind/human- brain/pain3.htm • http://www.docstoc.com/docs/ • http://www.google.fr/imgres • www.ksums.net • www.authorstream.com • http://www.docstoc.com/docs/70291468/Pain-Terminology-and-Pain-
  59. 59. 4/5/2014
  60. 60. 4/5/2014

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