Pain facts – 3

1. Pain facts – 3 Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD (physio) Mahatma Gandhi medical college and research institute – puducherry, India

2. Referred pain • Pain perceived at a location other than the site of the painful stimulus • What is radiating pain ?? • What is referred pain ??

3. Radiation or referral • Pain of myocardial infarction is located in the mid or left side of the chest where the heart is actually located. The pain can radiate to the left side of the jaw and into the left arm. • Referred pain is when the pain is located away from or adjacent to the organ involved. Referred pain would be when a person has pain only in their jaw or left arm, but not in the chest

4. Confusion still • ISSP does not clarify ??

5. Visceral pain • Does it respond to clamp?? • No • Ischemia • Distension • Active contractions • Diffuse, referred, autonomic

6. Organs and site of referred pain

7. Characteristics 1. segmental Renal colic – loin and scrotum 2. area of referral – tender hyperalgesic, 3. develops after sometime.

8. Mechanisms • Morley ‘ s theory • Axon reflex -= Sinclair • Convergent-projection- Ruch • Convergence-facilitation • Hyperexcitability • Thalamic-convergence

9. Morley ‘ s theory • It states that the involvement of adjacent somatic structures caused pain !! • Simultaneous ? • Can be the only symptom ? • Put to disuse

10. Axon reflex theory • primary sensory neurones have widely bifurcating axons and innervate both somatic and visceral targets, thus obscuring the source of afferent activity, and explaining the segmental nature of referred sensations.

11. Questions about axon theory • No such axons • No explanation to time delay No explanation to referred hyperalgesia

12. Convergent-projection- Ruch • visceral and somatic primary sensory neurones converge onto common spinal neurones • This theory proposes that the activity in ascending spinal pathways is misconstrued as originating from somatic structures ready explanation for the segmental nature but issue of referred hyperalgesia.??

13. convergence-facilitation theory • viscera were wholly insensitive and therefore that visceral afferent activity never of itself gave rise to pain. • He proposed instead that this activity was capable of creating an “irritable focus” within the spinal cord, so that other, segmentally appropriate, somatic inputs could now produce abnormal and, of course, referred pain sensations. • MacKenzie

14. convergence-facilitation theory • NO general acceptance, in part because it implicitly denied the existence of “true” visceral palm. However, the theory offers an explanation for referred hyperalgesia and, perhaps, the delay of referred sensations. • The concept of an irritable focus has more recently been resurrected with another label—central sensitization, which appears to be of major importance in hyperalgesia from somatic and visceral structures.

15. Supraspinal – theobald • interactions at supra spinal levels lead to the phenomenon. • But are there separate systems ??

16. What happens if we block area referredhyperalgesia lost tenderness lost , pain- loss – controversial

17. Summary • Referred pain • Features • Theories

18. Phantom pain • A phantom limb is the sensation that an amputated or missing limb (even an organ, like the breast) is still attached to the body and is moving appropriately with other body parts • Approximately 60 to 80% of individuals with an amputation experience phantom sensations in their amputated limb, and the majority of the sensations are painful

19. Phantom pain

20. Or simply!! • Painful sensations experienced in a missing limb . • Tooth and eye also possible • Stump pain is different.

21. phantom pains can also occur in people who are born without limbs and people who are paralyzed. • So phantom limb, phantom pain, stump pain

22. History • Ambrose Paire (1510) • Military surgeon • First explained • Mitchell (1979) coined the term – phantom pain

23. How frequent is it ?? • 4 – 90 % • Innumerable studies • Onset • Usually first week after amputation • Rarely months to years

24. Where is it ?? • Entire – 6% • Proximal – 10% • Distal – around 80 % • Approx figures changes with duration !!

25. Quality - No proper studies • Varied –Squeeze ,Clenching toes ,Nails digging • The missing limb often feels shorter • feel as distorted • can be made worse by stress, anxiety, and weather changes. • usually intermittent. • The frequency and intensity of attacks usually declines with time 70 % ----35 % in 2 years

26. Preamputation pain • Striking case reports • Location and character similar – • Vascular and traumatic amputees • Pain memory ? • Melzack (1990) – questioned the fact ?? • CNS lesions made pain disappear

27. Possible no relation • Military Vs civilian • Age, side, • Sex • Level of amputation

28. Etiology • Peripheral • Spinal • Supraspinal

29. Peripheral • Irritation in the severed nerve endings (called "neuromas"). • Gallamine and Local injection • Percussion of stump – increases pain • Stump end pathology ends pain ends

30. Spinal and thereon • Disinhibition of neurons at spinal level • Nerve injury – sensitization – spinal plasticity • In his 1989 paper,"Phantom Limbs, The Self And The Brain“ Melzack proposed the theory of the "neuromatrix.“

31. Mechanisms • the experience of the body is created by a wide network of interconnecting neural structures • the primary somatosensory cortex undergoes substantial reorganization after the loss of sensory input. • due to this reorganization in the somatosensory cortex, which is located in the postcentralgyrus, and which receives input from the limbs and body. • Stroke the Face – phantom pain

32. Etiology • Peripheral • Spinal • Supraspinal

33. Treatment • Yes it a form of chronic pain • Difficult to treat • 68 treatment , 50 still in use !! • TENS, massage, acupuncture,capsaicin ECT • 75% Vs 44 % placebo • mirror box visual feedback

34. Drugs • Carbamazepine and newer anticonvulsants • Antidepressants • IV calcitonin • Beta blockers • Depression or original which is treated ??

35. Invasive techniques • Stump revisions • Neuroma excision • Sympathectomy • Dorsal root entry – zone lesions • Spinal stimulation • Brain stimulation • Preemptive – role ??

36. What I do • A very low dose IV ketamine as premed • Always regional • Add opioids

37. VilliyanurRamachandran !! Statement by an international phantom pain authority The fingers were illusory, but the pain was real

38. If we give pain relief then

39. Is this phantom or real ? • Thank you all