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Pain asymbolia, also called pain dissociation, is a condition in which pain is experienced without unpleasantness. This usually results from injury to the brain, lobotomy, cingulotomy or morphine analgesia.
The ability to experience pain is essential for protection from injury, and recognition of the presence of injury. Episodic analgesia may occur under special circumstances, such as in the excitement of sport or war: a soldier on the battlefield may feel no pain for many hours from a traumatic amputation or other severe injury.
Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery. Such patients report that they have pain but are not bothered by it; they recognize the sensation of pain but suffer little, or not at all. Indifference to pain can also rarely be present from birth; these people have normal nerves on medical investigations, and find pain unpleasant, but do not avoid repetition of the pain stimulus.
Insensitivity to pain may also result from abnormalities in the nervous system. This is usually the result of acquired damage to the nerves, such as spinal cord injury, diabetes mellitus (diabetic neuropathy), or leprosy in countries where this is prevalent. These individuals are at risk of tissue damage due to undiscovered injury. People with diabetes-related nerve damage, for instance, sustain poorly healing foot ulcers as a result of decreased sensation.
Preexisting lesions of the insula may abolish the aversive quality of painful stimuli while preserving the location and intensity aspects. Typically, patients report that they have pain but are not bothered by it, they recognize the sensation of pain but are mostly or completely immune to suffering from it.
A much smaller number of people are insensitive to pain due to an inborn abnormality of the nervous system, known as "congenital insensitivity to pain". Children with this condition incur carelessly repeated damage to their tongue, eyes, joints, skin, and muscles. Some die before adulthood, and others have a reduced life expectancy. Most people with congenital insensitivity to pain have one of five hereditary sensory and autonomic neuropathies (which includes familial dysautonomia and congenital insensitivity to pain with anhidrosis). These conditions feature decreased sensitivity to pain together with other neurological abnormalties, particularly of the autonomic nervous system. A very rare syndrome with isolated congenital insensitivity to pain has been linked with mutations in the SCN9A gene, which codes for a sodium channel (Nav1.7) necessary in conducting pain nerve stimuli.
- ↑ Beecher, HK (1959). Measurement of subjective responses. New York: Oxford University Press. cited in Melzack, R; Wall, PD (1996). The challenge of pain (2 ed.). London: Penguin. p. 7. ISBN 978-0-14-025670-3.
- ↑ International Association for the Study of Pain: Pain Definitions [Retrieved 10 Sep 2011]. "Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage" Derived from Bonica JJ. The need of a taxonomy. Pain. 1979;6(3):247–8. doi:10.1016/0304-3959(79)90046-0. PMID 460931.
- ↑ Cite error: Invalid
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- ↑ 4.0 4.1 Nikola Grahek, Feeling pain and being in pain, Oldenburg, 2001. ISBN 3-8142-0780-7.
- ↑ 5.0 5.1 5.2 Nagasako EM, Oaklander AL, Dworkin RH. Congenital insensitivity to pain: an update. Pain. 2003;101(3):213–9. doi:10.1016/S0304-3959(02)00482-7. PMID 12583863.
- ↑ Template:Vcite book
- ↑ Lipsky BA, Berendt AR, Deery HG, Embil JM, Joseph WS, Karchmer AW, LeFrock JL, Lew DP, Mader JT, Norden C, Tan JS. Diagnosis and treatment of diabetic foot infections. Clin. Infect. Dis.. 2004;39(7):885–910. doi:10.1086/424846. PMID 15472838.
- ↑ (2006) Neuroscience: With STUDENT CONSULT Online Access, Philadelphia: Saunders.
- ↑ 9.0 9.1 Axelrod FB, Hilz MJ. Inherited autonomic neuropathies. Semin Neurol. 2003;23(4):381–90. doi:10.1055/s-2004-817722. PMID 15088259.
- ↑ Raouf R, Quick K, Wood JN. Pain as a channelopathy. J. Clin. Invest.. 2010;120(11):3745–52. doi:10.1172/JCI43158. PMID 21041956.
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