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Pathophysiology Gen. Unit#03 (A) (1).pptx
- 1. 1 Pathophysiology Pain Unit:VI Amjad Ali AssistantProfessor 02.10.2021
- 2. 2 Outlines: • Review theconcept of somatosensory pathway. • Describe the function of Nociceptors in response to pain information. • Describe the function of endogenous analgesic mechanism as they relate to transmission of pain information. • Describe the proposed mechanism of pain relief associated with the use of heat, cold and tense i.e. transcutaneous electrical nerve impulses.
- 3. 3 Pain Sensation of theaffected level of unpleasantness. OR Unpleasant sensations(either sensory or emotional) associated with either potential or actual tissue damage.
- 4. 4 TYPES OF PAIN •The most widely accepted classifications of pain are according to source or location, referral, and duration (acute or chronic). • Classification based on associated medical diagnosis (e.g., surgery, trauma, cancer, sickle cell disease, fibromyalgia) is useful in planning appropriate interventions.
- 5. 5 Cont…. • Cutaneous painis a sharp, burning pain that has its origin in the skin or subcutaneous tissues. • Deep pain is a more diffuse and throbbing pain that originates in structures such as the muscles, bones, and tendons and radiates to the surrounding tissues
- 6. 6 Cont… • Visceral painis a diffuse and poorly defined pain that results from stretching, distention, or ischemia of tissues in a body organ. • Acute pain is a self-limiting pain that lasts less than 6 months.
- 7. 7 Cont… Chronic pain ispersistent pain that lasts longer than 6 months, lacks the autonomic and somatic responses associated with acute pain, and is accompanied by loss of appetite, sleep disturbances, depression, and other debilitating responses.
- 8. 8 Cont… • Referred painis pain that originates at a visceral site but is perceived as originating in part of the body wall that is innervated by neurons entering the same segment of the nervous system.
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- 10. 10 Pain categories 1. Somatogenicpain is pain with cause (usually known) localised in the body tissue a/ nociceptive pain b/ neuropatic pain 2. Psychogenic pain is pain for which there is no known physical cause but processing of sensitive information in CNS is disturbed.
- 11. 11 Somatosensory System • Thesomatosensory system is the part of the sensory system concerned with the conscious perception of touch, pressure, pain, temperature, position, movement, and vibration, which arise from the muscles, joints, skin, and fascia. • The somatosensory system is a 3- neuron system that relays sensations detected in the periphery and conveys them via pathways through the spinal cord, brainstem, and thalamic relay nuclei to the sensory cortex in the parietal lobe.
- 12. 12 Cont.. Somatosensory information issequentially transmitted over three types of neurons: • First-order neurons, which transmit information from sensory receptors to dorsal horn neurons; • Second-order CNS association neurons, which communicate with various reflex circuits and transmit information to the thalamus; • Third-order neurons, which forward the information from the thalamus to the sensory cortex.
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- 15. 15 Nociceptive pain • Nociceptivepain results from direct activation of pain nerve fibers, either due to chemical, inflammatory or mechanical mediators. • Nociceptors are sensory receptors that detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue.
- 16. 16 Cont.…. • Nociceptors arefree nerve endings found in the skin, muscle, joints, bone and viscera. • Nerve endings contain transient receptor potential (TRP) channels that sense and detect damage. • They transduce a variety of noxious stimuli into receptor potentials, which in turn initiate action potential in the pain nerve fibers.
- 17. 17 Cont.….. • This actionpotential is transmitted to the spinal cord and makes a synaptic connection in lamina I and/or II. The cell bodies of Nociceptors are mainly in the dorsal root and trigeminal ganglia. • Nociceptors are not uniformly sensitive. They fall into several categories, depending on their responses to mechanical, thermal, and/or chemical stimulation liberated by the damage, tumor, and/or inflammation.
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- 20. 20 Thermotherapy Thermotherapy are usefuladjuncts for the treatment of musculoskeletal injuries and soft tissue injuries. Using ice or heat as a therapeutic intervention decreases pain in joint and muscle as well as soft tissues and they have opposite effects on tissue metabolism, blood flow, inflammation, edema and connective tissue extensibility.
- 21. 21 Heat • By increasingthe temperature of the skin/soft tissue, the blood flow increases by vasodilatation. • The metabolic rate and the tissue extensibility will also increase. Heat increases oxygen uptake and accelerates tissue healing, it also increases the activity of destructive enzymes, such as collagenase, and increases the catabolic rate.
- 22. 22 Heat • Heating ofsuperficial tissues can be achieved using hot packs, wax baths, towels, sunlight, heat wraps, steam baths/rooms. • During periods of hypothermia, falling core and skin temperatures lead to reflexive increases in sympathetic active vasoconstrictor nerve activity to reduce skin blood flow and conserve body heat • heat increases skin and joint temperature, improves blood circulation and muscle relaxation and decreases joint stiffness
- 23. 23 Cold • By decreasingthe temperature of the skin/soft tissue, the blood flow decreases by vasoconstriction. • It will be followed afterwards by a vasodilatation which will prevent against hypoxic damage (hunting reflex: If the cold pack is left on the skin for more than 10 minutes, the blood vessels will dilatate). • The tissue metabolism will decrease just like the neuronal excitability, inflammation, conduction rate and tissue extensibility.
- 24. 24 Cold • Cooling isachieved using ice packs, ice baths, cooling gel packs, cold air and sprays. • During periods of heat stress, increasing core and skin temperatures lead to reflexive increases in sympathetic active vasodilator nerve activity to increase skin blood flow. • Cold will numb the pain, decrease swelling, constrict blood vessels and block nerve impulses to the joint.
- 25. 25 Effect of Heatand cold
- 26. 26 Transcutaneous electrical nerve stimulation(TENS): • A TENS machine is a small, battery- operated device that has leads connected to electrodes. • small electrical impulses are delivered to the affected area of your body, which you feel as a tingling sensation. • Various therapeutic currents have been used for modulating clinical pain. Transcutaneous electrical nerve stimulation (TENS) is a low-frequency stimulator that delivers electrical impulses at a frequency of 0–200 Hz.
- 27. 27 Transcutaneous electrical nervestimulation (TENS): • The electrical impulses can block or reduce the pain signals going to the spinal cord and brain, which can help reduce or relieve pain or muscle spasm. • The electric currents can also stimulate the production of endorphins, which are the body's natural painkillers.
- 28. 28 Cont.… • It hasbeen shown to be an effective treatment modality for various types of musculoskeletal pain, such as osteoarthritic knee, and chronic low back pain.
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