Phantom pain

Phantom pain is pain that appears to arise from an amputated limb or body part; as many as 70% of amputees experience phantom pain. This pain may begin with sensations of tingling, heat and cold, or heaviness, followed by burning, cramping, or shooting pain. Phantom pain may disappear spontaneously or persist for many years.

The exact cause of phantom pain is not clearly understood. One proposed mechanism involves stimulation of the sensory pathway that had once originated in the amputated body part. An important point is that the sensory pathway originating in a given body part transmits impulses to the region of the somatosensory cortex devoted to that body part regardless of amputation. Stimulation at any point along this pathway results in the same sensation that would be produced by stimulation of the nociceptor in the body part itself. Following amputation of a body part, the ends of the afferent nerves arising from that body part become trapped in the scar tissue of the

Somatosensory Cortex (left arm)

Somatosensory Cortex (left arm)

Figure 8.3 Referred pain. The mechanism of referred pain involves convergence of visceral afferent neurons and cutaneous afferent neurons with the same second-order neurons in the dorsal horn of the spinal cord. In this example, the pain of angina that originates in the heart is referred to the left arm.

Figure 8.3 Referred pain. The mechanism of referred pain involves convergence of visceral afferent neurons and cutaneous afferent neurons with the same second-order neurons in the dorsal horn of the spinal cord. In this example, the pain of angina that originates in the heart is referred to the left arm.

stump. These afferent nerve endings exhibit increased sensitivity and are easily stimulated. Therefore, action potentials are generated at these nerve endings and transmitted to the area of the somatosensory cortex devoted to the amputated body part. This results in the perception of pain arising from the amputated portion of the body.

A second theory of phantom pain suggests that second-order neurons in the dorsal horn of the spinal cord become hyperactive. Spontaneous firing of these neurons causes transmission of nerve impulses to the brain and the perception of pain.

How To Reduce Acne Scarring

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Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

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