Pain is subjective

1. Pain is subjective • Self-experience • Experience depends on circumstances • Pain can cause many different reactions: • Activate autonomic system (heart rate, blood pressure, sweating, etc.) • Muscle activity • Mood (fear, anxiety, depression) • Prevent sleep

2. Pain occurs with different degrees of severity •   Mild pain: Does not interfere noticeably with everyday life • Moderate pain: May cause some annoyance and perceived as unpleasant • Severe chronic pain: Affects a person’s entire life in major ways

3. There are many forms of pain Mild pain: Does not interfere noticeably with everyday life Moderate pain: May cause some annoyance and may be perceived as unpleasant Severe pain: Affects a person’s entire life in major ways

4. Different forms of pain • Acute pain • Chronic pain • Somatic pain • Neuropathic pain • Central neuropathic pain

5. Pain has many different forms, but the same name Tinnitus has many different forms but the same name

6. There are different types of pain • Somatic and visceral pain (Stimulation of nociceptors) • Pain ceases when stimulation ceases • Neuropathic pain • Pain is related to the nervous system • Central neuropathic pain • Plastic changes in the function of the CNS • May be persistent

7. It is important to have different names for for different disorders • We cannot think about matters that do not have names • The same words is used to describe very different forms of tinnitus and pain • Using the same names for fundamentally different disorders is a disadvantage in studying and treating such disorders

8. Severe pain affects a person’s entire life in major ways • Prevent or disturb sleep • Interfere with or prevents intellectual work  • May cause suicide May involve limbic structures causing affective reactions Often accompanied by abnormal sensations from touch

9. How prevalent is severe pain? Some pain was reported by 86% of individuals above the age of 65 (Iowa study, 1994) The prevalence of severe pain was 33% for people at age 77 and above (Swedish study, 1996)

10. How prevalent is severe pain? Some pain was reported by 86% of individuals above the age of 65 (Iowa study, 1994) The prevalence of severe pain was 33% for people at age 77 and above (Swedish study, 1996)

11. Pain “The only tolerable pain is someone else’s pain” René Leriche, French surgeon, 1879–1955

12. There are different types of pain • Somatic and visceral pain (Stimulation of nociceptors) • Pain ceases when stimulation ceases • Neuropathic pain • Pain is related to the nervous system • Central neuropathic pain • Plastic changes in the function of the CNS • May be persistent

14. Central neuropathic pain: • Pain sensation caused by abnormal neural activity in the CNS • Hyperacusis: • Sounds are perceived louder than normal • Allodynia: • Sensation of pain from normally innocuous stimulation (such as light touch) • Hyperpathia: • Exaggerated and prolonged reactions to painful stimuli

15. Somatic and visceral pain (Stimulation of nociceptors)   • Burning (temperature) • Injury • Inflammation • Chemicals • Compression of spinal nerve roots (nervi nervorum)

16. Muscle pain

17. Relationship between commonly used terms to characterize muscle tension: Tone, stiffness, contracture, and spasm

18. Tension type headaches with trigger zones in the temporalis muscle (), in suboccipital, sternocleidomastoid and upper trapezius muscles (), from where pain attacks can be elicited

19. Neuropathic pain • Pain of the nervous system • Neuralgias • Anesthesia dolorosa • Root pain • Stroke pain

20. Neuropathic pain • All pain of neural origin The term is mostly used by neurologists for pain caused by disorders of peripheral nerves and cranial nerves

22. Central neuropathic pain • Plastic changes in the function of the CNS(WDR neurons, thalamus)

23. Acute pain may promote development of central neuropathic pain • Central neuropathic pain is a neurologic disorder

24. Acute pain sensation may not be a sign of pathology Pain sensation can be elicited by: • Stimulation of nociceptors • Overstimulation of other receptors

25. Acute pain has two phases: A fast (sharp) and a slow (burning) sensation • The slow and delayed pain is mediated by unmyelinated fibers (C-fibers). • The fast phase is mediated by myelinated fibers (A).

28. Fast and slow pain are different • Fast pain (stinging): • Well defined with regards to location • Its strength is defined • Slow pain (aching): • Diffuse, poorly localized anatomically • Difficult the estimate its strength

29. Different types of nerve fibers carry different kinds of pain

30. Temperature There are four different temperature receptors: Cool and warmth (sensory receptors) Cold and heat (nociceptors)

31. Temperature • Cool and warmth receptors mediate sensation of temperature • Cold and heat receptors are nociceptors that mediate sensation of pain. • Cool and warmth receptors are innervated by small myelinated (A fibers, diameter 1-5 m, conduction velocity 5-30 m/sec). • Cold and heat receptor are innervated by unmyelinated fibers (C-fibers, diameter 0.2-2 m; conduction velocity 0.5-1 m/sec).

37. Wide dynamic range neuron

38. THE ANTERIOR LATERAL SYSTEM MEDIATES PAIN SENSATIONS The spinothalamic tract is the best known of the anteriorlateral tracts

39. Spinothalamic tract

42. Ascending projections of the anterior portion of the STT from neurons in lamina IV-V of the spinal horn. VPI: Ventral posterior inferior (nuclei of thalamus); VPL: Ventral posterior lateral (nuclei of thalamus); SI: Primary somatosensory cortex; SII: secondary somatosensory cortex

43. Projections of the lateral portion of the STT from cells in lamina I of the dorsal horn

44. Projection of unmyelinated C fibers. Notice: Projection to SII is bilateral but only the SI receives input from C fibers

45. Spinoreticular tract

46. Spinomesencephalic tract

47. Pathways involved in mediating the sensation of nociceptor pain

48. Input to the periaquaductal gray (PAG) and pathways that modulate transmission of pain signals by the PAG through the rostral ventromedial medulla (RVM) pathway.

49. Dorsolateral pontomesencephalic tegmentum pathway (DLTP).

50. Descending pathways from raphe nucleus (NA-serotonin pathway)