Referred Pain (Physiology Seminar)

Prepared & Presented by:

Muhammad Haroon,
Muhammad Hassaan Khalid &
Rao Jahanzaib

from MBBS class of 2017.

1. Group Members Muhammad Haroon 240 Muhammad Hassaan Khalid 241 Rao Jahanzaib 242

2. Referred pain

3. Referred pain Definition Physiological Basis/ Mechanism Different Examples Importance

4. Definition pain perceived at a location other than the site of the painful stimulus. Irritation of a visceral organ frequently produces pain that is felt not at that site but in some somatic structure that may be a considerable distance away. Such pain is said to be referred to the somatic structure. also called reflective pain

5. Referred pain mechanism 2 mechanisms Dermatomal rule C onvergence–projection theory

6. R eferred pain mechanism ( Dermatomal rule) Dermatomal rule - When pain is referred, it is usually to a structure that developed from the same embryonic segment or dermatome as the structure in which the pain originates. This principle is called dermatomal rule FOR INSTANCE: the heart and the inner aspect of left arm Testicle & ureter+kidney (from urogenital ridge)

7. Referred pain mechanism (Convergence – projection theory) Convergence– projection theory Second mechanism for referred pain may be convergence of somatic and visceral pain fibers on the same second-order neurons in the dorsal horn that project to the thalamus and then to the somatosensory cortex (Figure 10–3). This is called the convergence– projection theory.

8. Referred pain mechanism (Convergence– projection theory) Somatic and visceral neurons converge in lamina I–VI of the ipsilateral dorsal horn Neurons in lamina VII receive afferents from both sides of the body explains referral of pain to the side opposite that of the source of pain i . e. affected organ.

9. Convergence– projection theory

10. Convergence– projection theory

11. Convergence– projection theory The somatic nociceptive fibers normally do not activate the second-order neurons. But……..

12. Note However, sites of referred pain are not stereotyped, and unusual reference sites occur with considerable frequency. FOR INSTANCE Cardiac pain, for instance, is usually referred to Upper chest/left limb But it may be referred to the right arm, the abdominal region, or even the back and neck.

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14. Visceral Pain Pain from the different viscera of the abdomen and chest . transmitted through small type C pain fibers Causes of True Visceral Pain : 1. Ischemia 2. Chemical Stimuli 3. Spasm of a Hollow Viscus 4. Overdistention of a Hollow Viscus

15. Localization of Visceral Pain Pain from the different viscera is frequently difficult to localize because : patient’s brain does not know from firsthand experience that the different internal organs exist. sensations from the abdomen and thorax are transmitted through two pathways to the central nervous system—the true visceral pathway and the parietal pathway.

16. True visceral pain is transmitted via pain sensory fibers within the autonomic nerve bundles, and the sensations are referred to surface areas of the body often far from the painful organ. parietal sensations are conducted directly into local spinal nerves from the parietal peritoneum, pleura, or pericardium, and these sensations are usually localized directly over the painful area.

17. Localization of Referred Pain Transmitted via Visceral Pathways. person generally localizes visceral in the dermatomal segment from which the visceral organ originated in the embryo. Pain from the viscera is frequently localized to two surface areas of the body at the same time because of the dual transmission of pain through the referred visceral pathway and the direct parietal pathway.

18. Examples Upper chest/left limb Myocardial ischaemia Right tip of scapula Liver, gallbladder Left shoulder Thoracic diaphragm, Spleen ( Kehr's sign, lung Back Pancreas Umblicus Small intestine ; appendex

19. Importance Knowledge of the different types of referred pain is important in clinical diagnosis because in many visceral ailments the only clinical sign is referred pain.