Paralysis
23254
221976135
2008-06-26T23:19:22Z
69.157.120.253
{{Expand|date=January 2008}}
{{Unreferenced|date=February 2007}}
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::''Paralysed redirects here. For other uses see [[Paralysed (disambiguation)]]''
'''Paralysis''' is the complete loss of [[muscle]] function for one or more muscle groups. Paralysis can cause loss of feeling or loss of mobility in the affected area.
==Causes==
Paralysis is most often caused by damage to the [[nervous system]] or [[brain]], especially the [[spinal cord]]. Partial paralysis can also occur in the [[REM stage of sleep]]. Major causes are [[stroke]], [[Physical trauma|trauma]], [[poliomyelitis]], [[amyotrophic lateral sclerosis]] (ALS), [[botulism]], [[spina bifida]], [[multiple sclerosis]], and [[Guillain-Barré syndrome]].
Poisons that interfere with [[action potential|nerve function]], such as [[curare]], can also cause paralysis. Many causes of this are varied, and could also be unknown.
==Variations==
Paralysis may be localized, or generalized, or it may follow a certain pattern. For example, localized paralysis occurs in [[Bell's palsy]] where one side of the face may be paralyzed due to inflammation of the [[facial nerve]] on that side. Patients with [[stroke]] may be weak throughout their body (global paralysis) or have [[hemiplegia]] (weakness on one side of the body) or other patterns of paralysis depending on the area of damage in the brain. Other patterns of paralysis arise due to different [[lesion]]s and their [[sequela]]e. For example, lower [[spinal cord]] damage from a severe back injury may result in [[paraplegia]], while an injury higher up on the spinal cord, such as a neck injury, can cause [[quadriplegia]]. Patients with [[paraplegia]] or [[quadriplegia]] often use equipment such as a [[wheelchair]] or [[standing frame]] for mobility and to regain some independence.
Most paralyses caused by nervous system damage are constant in nature; however, there are forms of [[periodic paralysis]], including [[sleep paralysis]], which are caused by other factors.
==Paralysis in the animal world==
Many species of animals use paralyzing toxins in order to capture prey, evade predation, or both. One famous example is the [[tetrodotoxin]] of fish species such as ''[[Takifugu rubripes]]'', the famously lethal [[pufferfish]] of Japanese [[fugu]]. This toxin works by binding to [[sodium channels]] in nerve cells, preventing the cells' proper function. A non-lethal dose of this toxin results in temporary paralysis. This toxin is also present in many other species ranging from toads to [[nemertea]]ns.
Another interesting use of paralysis in the natural world is the behavior of some species of [[wasp]]. In order to complete the reproductive cycle, the female wasp first paralyzes a prey item such as a grasshopper and then places it into her nest. Eggs are then laid on the paralyzed insect, which is devoured by the [[larvae]] after they hatch. Many snakes also exhibit powerful [[neurotoxins]] that can cause non-permanent paralysis or [[death]].
Paralysis can be seen in breeds of dogs that are chondrodysplastic. These dogs have short legs, and may also have short muzzles. Their intervertebral disc material can calcify and become more brittle. In such cases, the disc may rupture, with disc material ending up in the spinal canal, or rupturing more laterally to press on spinal nerves. A minor rupture may only result in [[paresis]], but a major rupture can cause enough damage to result in complete paralysis. If no signs of pain can be elicited, surgery should be performed within 24 hours of the incident, to remove the disc material and relieve pressure on the [[spinal cord]]. After 24 hours, the chance of recovery declines rapidly, since with continued pressure, the spinal cord tissue deteriorates and dies.
Another type of paralysis is caused by a fibrocartilaginous embolism. This is a microscopic piece of disc material that breaks off and becomes lodged in a spinal artery. Nerves served by the artery will die when deprived of blood.
The [[German Shepherd]] is especially prone to developing degenerative [[myelopathy]]. This is a deterioration of nerves in the spinal cord, starting in the posterior part of the cord. Dogs so affected will become gradually weaker in the hind legs as nerves die off. Eventually their hind legs become useless. They often also exhibit fecal and urinary incontinence. As the disease progresses, the paresis and paralysis gradually move forward. This disease also affects other large breeds of dogs. It is suspected to be an autoimmune problem.
Cats with [[heart murmur]]s may develop blood clots which travel through arteries. If the clot is large enough to block one or both femoral arteries, there may be hind leg paralysis because the major source of blood flow to the hind leg is blocked.
==See also==
* [[Spinal cord injury]]
* [[Paraplegia]]
* [[Quadriplegia]]
* [[Muscle relaxant]]
* [[Ptosis]]
* [[Sleep paralysis]]
* [[Hemiparesis]]
* [[Beriberi]]
* [[Neuroprosthetics]]
* [[Brain-computer interface]]
* [[Tonic immobility]]
* [[Cerebral palsy]]
* [[Cobra Toxin]]
{{Cerebral palsy and other paralytic syndromes}}
[[Category:Neurological disorders]]
[[Category:Symptoms]]
[[ay:Such'u]]
[[bn:পক্ষাঘাত]]
[[cs:Ochrnutí]]
[[de:Lähmung]]
[[es:Parálisis]]
[[fr:Paralysie]]
[[hr:Paraliza]]
[[it:Paralisi]]
[[he:שיתוק]]
[[nl:Verlamming]]
[[ja:麻痺]]
[[no:Lammelse]]
[[pl:Porażenie]]
[[pt:Paralisia]]
[[ru:Паралич]]
[[simple:Paralysis]]
[[fi:Halvaus]]
[[te:పక్షవాతం]]