Paralysis

Paralysis is a loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage as well as motor. In the United States, roughly 1 in 50 people have been diagnosed with some form of permanent or transient paralysis. The word comes from the Greek παράλυσις, 'disabling of the nerves', itself from παρά (para), 'beside, by' and λύσις (lysis), 'making loose'. A paralysis accompanied by involuntary tremors is usually called 'palsy'. Paralysis is a loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage as well as motor. In the United States, roughly 1 in 50 people have been diagnosed with some form of permanent or transient paralysis. The word comes from the Greek παράλυσις, 'disabling of the nerves', itself from παρά (para), 'beside, by' and λύσις (lysis), 'making loose'. A paralysis accompanied by involuntary tremors is usually called 'palsy'. Paralysis is most often caused by damage in the nervous system, especially the spinal cord. Other major causes are stroke, trauma with nerve injury, poliomyelitis, cerebral palsy, peripheral neuropathy, Parkinson's disease, ALS, botulism, spina bifida, multiple sclerosis, and Guillain–Barré syndrome. Temporary paralysis occurs during REM sleep, and dysregulation of this system can lead to episodes of waking paralysis. Drugs that interfere with nerve function, such as curare, can also cause paralysis. Pseudoparalysis (pseudo- meaning 'false, not genuine', from Greek ψεῦδος) is voluntary restriction or inhibition of motion because of pain, incoordination, orgasm, or other cause, and is not due to actual muscular paralysis. In an infant, it may be a symptom of congenital syphilis. Pseudoparalysis can be caused by extreme mental stresses, and is a common feature of mental disorders such as panic anxiety disorder. Paralysis can occur in localised or generalised forms, or it may follow a certain pattern. Most paralyses caused by nervous-system damage (e.g., spinal cord injuries) are constant in nature; however, some forms of periodic paralysis, including sleep paralysis, are caused by other factors. Paralysis can occur in newborns due to a congenital defect known as spina bifida. Spina bifida causes one or more of the vertebrae to fail to form vertebral arches within the infant, which allows the spinal cord to protrude from the rest of the spine. In extreme cases, this can cause spinal cord function inferior to the missing vertebral arches to cease. This cessation of spinal cord function can result in paralysis of lower extremities. Documented cases of paralysis of the anal sphincter in newborns have been observed when spina bifida has gone untreated. While life-threatening, many cases of spina bifida can be corrected surgically if operated on within 72 hours of birth. Ascending paralysis presents in the lower limbs before the upper limbs. It can be associated with: Ascending paralysis contrasts with descending paralysis, which occurs in conditions such as botulism. Many animal species use paralysing toxins to capture prey, evade predation, or both. It was shown that in stimulated muscles the decrease in frequency of the miniature potentials runs parallel to the decrease in postsynaptic potential as well as to the decrease in muscle contraction. In invertebrates, this clearly indicates that, e.g., Microbracon (wasp genus) venom causes paralysis of the neuromuscular system by acting at a presynaptic site. Philanthus venom inhibits the fast as well as the slow neuromuscular system at identical concentrations. It causes a decrease in the frequency of the miniature potentials without affecting their amplitude significantly. Some species of wasp, to complete the reproductive cycle, the female wasp paralyses a prey item such as a grasshopper and places it in her nest. In the species Philanthus gibbosus, the paralysed insect (most often a bee species) is coated in a thick layer of pollen. The adult P. gibbosus then lays eggs in the paralysed insect, which is devoured by the larvae when they hatch.