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Specialty Neurology, neurosurgery, psychiatry

Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 people have been diagnosed with some form of permanent or transient paralysis. [1] The word "paralysis" derives from the Greek παράλυσις, meaning "disabling of the nerves" [2] from παρά (para) meaning "beside, by" [3] and λύσις (lysis) meaning "making loose". [4] A paralysis accompanied by involuntary tremors is usually called "palsy". [5] [6]



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 [7] ) is voluntary restriction or inhibition of motion because of pain, incoordination, orgasm, or other cause, and is not due to actual muscular paralysis. [8] In an infant, it may be a symptom of congenital syphilis. [9] Pseudoparalysis can be caused by extreme mental stresses, and is a common feature of mental disorders such as panic anxiety disorder. [10]


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. [11] [12]

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. [12] 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. [11] 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.

Other animals

Many animal species use paralyzing toxins to capture prey, evade predation, or both. In stimulated muscles, the decrease in frequency of the miniature potentials runs parallel to the decrease in postsynaptic potential, and 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 both the fast and slow neuromuscular system at identical concentrations. It causes a decrease in the frequency of the miniature potentials without affecting their amplitude significantly.[ citation needed ]


In 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. [14]


A well-known example of a vertebrate-produced paralyzing toxin 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, inhibiting 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 nemerteans.

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 cut off circulation. 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 Dog 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. Affected dogs will become gradually weaker in the hind legs as nerves die off. Eventually, their hind legs become useless. They often also exhibit faecal 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 a heart murmur may develop blood clots that travel through arteries. If a 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.

Many snakes exhibit powerful neurotoxins that can cause non-permanent paralysis or death. Also, many trees contain neurotoxins.

See also

Related Research Articles

Tetraplegia, also known as quadriplegia, is paralysis caused by illness or injury that results in the partial or total loss of use of all four limbs and torso; paraplegia is similar but does not affect the arms. The loss is usually sensory and motor, which means that both sensation and control are lost. The paralysis may be flaccid or spastic.

<span class="mw-page-title-main">Spina bifida</span> Birth defect of the spinal cord

Spina bifida is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, meningocele and myelomeningocele. Meningocele and myelomeningocele may be grouped as spina bifida cystica. The most common location is the lower back, but in rare cases it may be in the middle back or neck.

<span class="mw-page-title-main">Brachial plexus</span> Network of nerves

The brachial plexus is a network of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve. This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit. It supplies afferent and efferent nerve fibers to the chest, shoulder, arm, forearm, and hand.

<span class="mw-page-title-main">Phrenic nerve</span>

The phrenic nerve is a mixed motor/sensory nerve which originates from the C3-C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. In humans, the right and left phrenic nerves are primarily supplied by the C4 spinal nerve, but there is also contribution from the C3 and C5 spinal nerves. From its origin in the neck, the nerve travels downward into the chest to pass between the heart and lungs towards the diaphragm.

The ankle jerk reflex, also known as the Achilles reflex, occurs when the Achilles tendon is tapped while the foot is dorsiflexed. It is a type of stretch reflex that tests the function of the gastrocnemius muscle and the nerve that supplies it. A positive result would be the jerking of the foot towards its plantar surface. Being a deep tendon reflex, it is monosynaptic. It is also a stretch reflex. These are monosynaptic spinal segmental reflexes. When they are intact, integrity of the following is confirmed: cutaneous innervation, motor supply, and cortical input to the corresponding spinal segment.

<span class="mw-page-title-main">Paraplegia</span> Impairment of motor and sensory functions in the lower limbs

Paraplegia, or paraparesis, is an impairment in motor or sensory function of the lower extremities. The word comes from Ionic Greek (παραπληγίη) "half-stricken". It is usually caused by spinal cord injury or a congenital condition that affects the neural (brain) elements of the spinal canal. The area of the spinal canal that is affected in paraplegia is either the thoracic, lumbar, or sacral regions. If four limbs are affected by paralysis, tetraplegia or quadriplegia is the correct term. If only one limb is affected, the correct term is monoplegia. Spastic paraplegia is a form of paraplegia defined by spasticity of the affected muscles, rather than flaccid paralysis.

<span class="mw-page-title-main">Pyramidal tracts</span> Include both the corticobulbar tract and the corticospinal tract

The pyramidal tracts include both the corticobulbar tract and the corticospinal tract. These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.

<span class="mw-page-title-main">Spinal cord injury</span> Injury to the main nerve bundle in the back of humans

A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. Symptoms may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cord below the level of the injury. Injury can occur at any level of the spinal cord and can be complete, with a total loss of sensation and muscle function at lower sacral segments, or incomplete, meaning some nervous signals are able to travel past the injured area of the cord up to the Sacral S4-5 spinal cord segments. Depending on the location and severity of damage, the symptoms vary, from numbness to paralysis, including bowel or bladder incontinence. Long term outcomes also range widely, from full recovery to permanent tetraplegia or paraplegia. Complications can include muscle atrophy, loss of voluntary motor control, spasticity, pressure sores, infections, and breathing problems.

<span class="mw-page-title-main">Brachial plexus injury</span> Medical condition

A brachial plexus injury (BPI), also known as brachial plexus lesion, is an injury to the brachial plexus, the network of nerves that conducts signals from the spinal cord to the shoulder, arm and hand. These nerves originate in the fifth, sixth, seventh and eighth cervical (C5–C8), and first thoracic (T1) spinal nerves, and innervate the muscles and skin of the chest, shoulder, arm and hand.

<span class="mw-page-title-main">Foot drop</span> Gait abnormality

Foot drop is a gait abnormality in which the dropping of the forefoot happens due to weakness, irritation or damage to the deep fibular nerve, including the sciatic nerve, or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. Foot drop is characterized by inability or impaired ability to raise the toes or raise the foot from the ankle (dorsiflexion). Foot drop may be temporary or permanent, depending on the extent of muscle weakness or paralysis and it can occur in one or both feet. In walking, the raised leg is slightly bent at the knee to prevent the foot from dragging along the ground.

Tethered cord syndrome (TCS) refers to a group of neurological disorders that relate to malformations of the spinal cord. Various forms include tight filum terminale, lipomeningomyelocele, split cord malformations (diastematomyelia), occult, dermal sinus tracts, and dermoids. All forms involve the pulling of the spinal cord at the base of the spinal canal, literally a tethered cord. The spinal cord normally hangs loose in the canal, free to move up and down with growth, and with bending and stretching. A tethered cord, however, is held taut at the end or at some point in the spinal canal. In children, a tethered cord can force the spinal cord to stretch as they grow. In adults the spinal cord stretches in the course of normal activity, usually leading to progressive spinal cord damage if untreated. TCS is often associated with the closure of a spina bifida. It can be congenital, such as in tight filum terminale, or the result of injury later in life.

Diastematomyelia is a congenital disorder in which a part of the spinal cord is split, usually at the level of the upper lumbar vertebra in the longitudinal (sagittal) direction. Females are affected much more commonly than males. This condition occurs in the presence of an osseous, cartilaginous or fibrous septum in the central portion of the spinal canal which then produces a complete or incomplete sagittal division of the spinal cord into two hemicords. When the split does not reunite distally to the spur, the condition is referred to as diplomyelia, which is true duplication of the spinal cord.

<span class="mw-page-title-main">Central nervous system disease</span> Disease of the brain or spinal cord

Central nervous system diseases, also known as central nervous system disorders, are a group of neurological disorders that affect the structure or function of the brain or spinal cord, which collectively form the central nervous system (CNS). These disorders may be caused by such things as infection, injury, blood clots, age related degeneration, cancer, autoimmune disfunction, and birth defects. The symptoms vary widely, as do the treatments.

Nervous system diseases, also known as nervous system or neurological disorders, refers to a small class of medical conditions affecting the nervous system. This category encompasses over 600 different conditions, including genetic disorders, infections, cancer, seizure disorders, conditions with a cardiovascular origin, congenital and developmental disorders, and degenerative disorders.

<span class="mw-page-title-main">Spinal cord</span> Long, tubular central nervous system structure in the vertebral column

The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around 45 cm (18 in) long in adult men and around 43 cm (17 in) long in adult women. The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area.

<span class="mw-page-title-main">Spinal disease</span>

Spinal disease refers to a condition impairing the backbone. These include various diseases of the back or spine ("dorso-"), such as kyphosis. Dorsalgia refers to back pain. Some other spinal diseases include spinal muscular atrophy, ankylosing spondylitis, lumbar spinal stenosis, spina bifida, spinal tumors, osteoporosis and cauda equina syndrome.

<span class="mw-page-title-main">Smile surgery</span>

Smile surgery or smile reconstruction is a surgical procedure that restores the smile for people with facial nerve paralysis. Facial nerve paralysis is a relatively common condition with a yearly incidence of 0.25% leading to function loss of the mimic muscles. The facial nerve gives off several branches in the face. If one or more facial nerve branches are paralysed, the corresponding mimetic muscles lose their ability to contract. This may lead to several symptoms such as incomplete eye closure with or without exposure keratitis, oral incompetence, poor articulation, dental caries, drooling, and a low self-esteem. This is because the different branches innervate the frontalis muscle, orbicularis oculi and oris muscles, lip elevators and depressors, and the platysma. The elevators of the upper lip and corner of the mouth are innervated by the zygomatic and buccal branches. When these branches are paralysed, there is an inability to create a symmetric smile.

<span class="mw-page-title-main">Vertebral column</span> Bony structure found in vertebrates

The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord found in all chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as lumbar punctures. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.


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  3. Liddell & Scott 1940 , παρά
  4. Liddell & Scott 1940 , λύσις
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  7. Liddell & Scott 1940 , ψεῦδος
  8. TheFreeDictionary > pseudoparalysis, in turn citing The American Heritage Medical Dictionary 2007, 2004
  9. Workowski KA, Berman SM (August 2006). "Sexually transmitted diseases treatment guidelines, 2006". MMWR Recomm Rep. 55 (RR–11): 1–94. PMID   16888612. ... evidence of congenital syphilis (e.g., nonimmune hydrops, jaundice, hepatosplenomegaly, rhinitis, skin rash, and/or pseudoparalysis of an extremity).
  10. "". Archived from the original on 2018-07-30. Retrieved 2017-06-06.
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  13. MedlinePlus Encyclopedia : Tick paralysis
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