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WHY DOES ENDOMETRIOSIS CAUSE SO MUCH PAIN?

WHY DOES ENDOMETRIOSIS CAUSE SO MUCH PAIN?. Dr Michael W Platt MA MB BS FRCA

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WHY DOES ENDOMETRIOSIS CAUSE SO MUCH PAIN?

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  1. WHY DOES ENDOMETRIOSIS CAUSE SO MUCH PAIN? Dr Michael W Platt MA MB BS FRCA Lead Clinician in Pain Medicine, Consultant in Anaesthetics, Honorary Senior Lecturer, Faculty of Medicine, Imperial College London,Department of Anaesthetics St Mary's Hospital, Imperial College Healthcare NHS Trust Praed Street, London W2 1NY

  2. The pain associated with Endometriosis is the most difficult symptom to cope with for most women. For many, the pain they suffer severely interferes with every day life. It can be constant or it can be cyclical and coincide with a woman’s period. Dr Michael W PlattImperial College

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  6. What is pain? • Emotional • Sensory • Acute or Chronic • Totally subjective • Can be described qualitatively • Can be graded quantitatively Dr Michael W PlattImperial College

  7. What is pain? Dr Michael W PlattImperial College

  8. What is pain? • Can be graded quantitatively: Dr Michael W PlattImperial College

  9. Why do we have pain? • Recognition of self • Protection from trauma • Reduction of trauma • Warning sign of illness • Warning sign of infection Dr Michael W PlattImperial College

  10. What happens when pain is absent? • Congenital insensitivity to pain • Sensory nerve damage secondary to disease • Diabetes • Stroke • Trauma • Syphilis • Leprosy Dr Michael W PlattImperial College

  11. Pain • Acute (physiological) Pain: • An unpleasant sensory and emotional experience associated with actual or potential tissue damage. • Chronic (pathological, intractible) Pain: • Pain in the absence of, or persisting following the removal of, a noxious stimulus. Dr Michael W PlattImperial College

  12. PAIN • Acute: Post-trauma, surgery etc. • Chronic: • Neuropathic pain • Mechanical pain • Chronic inflammation • Complex regional pain syndrome • Cancer pain Dr Michael W PlattImperial College

  13. Complicated neurobiology of pain • Not a simple ‘hard-wired’ system. • Long-term changes occur in the PNS and CNS following a noxious stimulus. • This ‘plasticity’ changes the body’s response to further stimuli Dr Michael W PlattImperial College

  14. Pain Pathways • Nociceptor • Axon • Dorsal Root Ganglion • Dorsal Root • Internuncial neurones • Cross-over to opposite side • Thalamus and Cortex Dr Michael W PlattImperial College

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  16. Peripheral sensitisation • Inflammatory response:Release of mediators from mast cells etc: • Substance P • neurokinin A • calcitonin gene-related peptide • lead to further release of ‘inflammatory soup’: • K, 5-HT, bradykinin, histamine etc • Act to sensitise high-threshold receptors Dr Michael W PlattImperial College

  17. ‘Neuropathic pain’ • Burning, sharp, stabbing sensations • eg diabetic neuropathy, post-amputation pain etc. • Treatment of peripheral neuropathic pain include tricyclic antidepressants, anti-convulsants, clonidine, opioids, local anaesthetics and anti-arrhythmic agents. Dr Michael W PlattImperial College

  18. Sympathetic nervous system • Important role in generation and maintenance of chronic pain states. • ‘Complex regional pain syndromes: • Sympathetic dysfunction: • vasomotor & sudomotor changes • abnormal hair & nail growth • osteoporosis • sensory symptoms: burning, hyperalgesis, allodynia Dr Michael W PlattImperial College

  19. Gate Theory of Pain Dr Michael W PlattImperial College

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  21. Central sensitisation • Changes that occur in the dorsal horn in response to an injury, following barrage of stimuli into the horn. • Phenomenon of ‘wind-up’ involving the NMDA receptor, making neurons more sensitive - ie sensitising them. • Expansion in receptive field size. Dr Michael W PlattImperial College

  22. Ascending tracts • 2nd order neurons ascend in spinothalamic, spinoreticular and spinomesencephalic tracts. • Terminate in structures throughout the brain stem, thalamus, and cortex. • Thalamus has 2 main groups of relays: • sensory discriminative aspects • affective-motivational aspects Dr Michael W PlattImperial College

  23. Descending modulation • descending inhibitory modulation from: • hypothalamus • PAG • locus coeruleus • nucleus raphe magnus • etc • Involves opioids, 5-HT, n-adr, GABA Dr Michael W PlattImperial College

  24. Visceral Pain • There are specific nociceptors originating in viscera. • They respond to: • tension (contraction) • chemical nociception • sensitisation of nociceptors • effects of ischaemia Dr Michael W PlattImperial College

  25. Concept of referred pain • Visceral nociceptors rarely activated • Much more common to activate somatic nociceptors • Spinal cord and brain interpret visceral signals as emanating from somatic source • Convergence of visceral and somatic afferents may account for this Dr Michael W PlattImperial College

  26. Diagnosis of Pain in Endometriosis • Acute, cyclical pain – due to pressure, chemical irritation, nerve compression • Chronic, non-cyclical pain – due to neuropathic pain, sources outside the pelvis (back, groin, etc.) • Other visceral pain – especially bladder pain. Dr Michael W PlattImperial College

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  30. Measurement of Pain • Visual Analogue Score • make as objective as possible • Straight line 10 cm long • No other markings • Personality inventories • Help to score chronic pain in terms of personality type and stress markers. Dr Michael W PlattImperial College

  31. Treatment of Pain in Endometriosis • Acute Pain: • NSAIDS • Hormonal • Oral Contraceptive • Systemic analgesia, opioids • Other techniques (TENS, Acupuncture) Dr Michael W PlattImperial College

  32. Pain Ladder • Minor pain: paracetamol, aspirin • Moderate pain: • combination with minor opioids • Co-proxamol (propoxifine), Co-dydramol (codeine) • Minor opioids alone - eg Pethidine, Tramadol • Severe pain: • Opioids: Morphine etc. Dr Michael W PlattImperial College

  33. Endometriosis and Inflammatory Pain: Use of NSAIDS • Cyclo-oxygenase pathway blocked • 2 forms: • COX1 & COX2 • COX1 always present • COX2 only induced by inflammation • Also have central role, where both COX1 & COX2 are found as neuro-transmitters Dr Michael W PlattImperial College

  34. NSAIDS • COX 2 antagonists preferable where there is high-risk of peptic ulceration / bleeding • Still not 100% guarantee. Dr Michael W PlattImperial College

  35. Treatment of Pain in Endometriosis • Chronic / Intractable Pain: • Multiple modality pain clinic - holistic approach • Drugs • Nerve blocks • TENS, Acupuncture • Physio, occupational Ther., Psychology Dr Michael W PlattImperial College

  36. Neuropathic Pain in Endometriosis • Not responsive to opioids • Two main classes of drugs used: • Tricyclic antidepressants (esp Amitriptyline) • Anti-epileptics: • Carbamazepine • Sodium valproate • Clonazepam • Gabapentin (Pregaballin) Dr Michael W PlattImperial College

  37. Gracilis Adductor longus Adductor brevis Adductor magnus Obturator externus Obturator internus Dr Michael W PlattImperial College

  38. Other complicating factors • Psychosocial & spiritual processes strongly influence the impact and expression of pain. • (Saunders 1985, Portenoy 1992; Breitbart 1994) Dr Michael W PlattImperial College

  39. Some factors: • Pain interrelated with: • depression (r = 0.33 with pain) • lack of family support (r = -0.15 with pain) • desire for death (r = 0.47 with depression) Dr Michael W PlattImperial College

  40. Some correlates with severe pain: • Patient anxiety: r = 0.30 • Communication problems: r = 0.29 • Constipation: r = 0.24 • Poor co-ordination: r = 0.21 • Family anxiety: r = 0.19 • Nausea: r = 0.19 • Vomiting: r = 0.13 • Other symptoms: r = 0.11 Dr Michael W PlattImperial College

  41. Factors that diminish quality of life: Pain Other symptoms Psychological distress Spiritual/existential distress Family distress Social distress Financial needs Health care concerns (eg poor communication) Perception & appraisal of pain Expression of suffering A MODEL OF SUFFERING

  42. Summary • The pain system is a very complex one. • Endometrial Pain may be difficult to treat due to a variety of causes, and these should be addressed in the management of the patient: • Adequate pain assessment, including those factors which are inter-related is essential. Dr Michael W PlattImperial College

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