referred pain (physiology seminar)

Group Members

1)Muhammad Haroon240

2)Muhammad Hassaan Khalid 241

3)Rao Jahanzaib242

Referred pain

Referred pain

Definition

Physiological Basis/ Mechanism

Different Examples

Importance

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

Referred pain mechanism

2 mechanisms Dermatomal rule

Convergence–projection theory

Referred 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)

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.

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.

Convergence– projection theory

Convergence– projection theory

Convergence– projection theory

If prolongation of visceral stimulus

facilitation of the somatic fiber endings

stimulate the second order neurons

brain interprets activity in a pathway as arising from somatic sources

Referred pain in somatic area

The somatic nociceptive fibers normally do not activate the second-order neurons. But……..

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.

..........

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

Localization of Visceral Pain

Pain from the different viscera is frequently difficult to localize because :

1. patient’s brain does not know from firsthand experience that the different internal organs exist.

2. sensations from the abdomen and thorax are transmitted through two pathways to the central nervous system—the true visceral pathway and the parietal pathway.

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.

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.

Examples

Upper chest/left limb

o Myocardial ischaemia

Right tip of scapula

o Liver, gallbladder

Left shoulder

o Thoracic diaphragm, Spleen (Kehr's sign, lung

Back

o Pancreas

Umblicus

o Small intestine ;appendex

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.