Ataxia
Encyclopedia
Ataxia is a neurological
sign
and symptom
that consists of gross lack of coordination
of muscle
movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system
that coordinate movement, such as the cerebellum
. Several possible causes exist for these patterns of neurological dysfunction. The term "dystaxia" is a rarely-used synonym.
The International Ataxia Awareness Day is observed on September 25 each year.
is used to indicate ataxia that is due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits, such as antagonist hypotonia
, asynergy
, dysmetria
, dyschronometria
, and dysdiadochokinesia
. How and where these abnormalities manifest themselves depends on which cerebellar structures have been damaged, and whether the lesion is bilateral or unilateral.
is employed to indicate ataxia due to loss of proprioception
, the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the dorsal columns of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain which receive positional information, including the cerebellum, thalamus
, and parietal lobe
s.
Sensory ataxia presents itself with an unsteady "stomping" gait with heavy heel
strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by visual input
, such as in poorly lit environments.
Physicians can find evidence of sensory ataxia during physical examination
by having the patient stand with his/her feet together and eye
s shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall. This is called a positive Romberg's test
. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when the patient is standing with arms and hands extended toward the physician, if the eyes are closed, the patient's finger will tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").
, which in acute and unilateral cases is associated with prominent vertigo
, nausea
and vomiting
. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and dysequilibrium may be the sole presentation.
(such as stroke
, brain tumour, multiple sclerosis
) will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum, sensory if in the dorsal spinal cord (and rarely in the thalamus
or parietal lobe
), vestibular if in the vestibular system (including the vestibular areas of the cerebral cortex
).
, which is capable of causing reversible cerebellar and vestibular ataxia. Other examples include various prescription drugs (e.g. most antiepileptic drugs have cerebellar ataxia as a possible adverse effect
), Lithium level over 1.5mEq/L, cannabis
ingestion and various other recreational drugs (e.g. ketamine
, PCP
or dextromethorphan
, all of which are NMDA receptor antagonist
s that produce a dissociative state at high doses). Exposure to high levels of methylmercury
, through consumption of fish with high mercury concentrations, is also a known cause of ataxia and other neurological disorders
deficiency
may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.
may cause generalised or localised sensory ataxia (e.g. a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.
, high altitude cerebral oedema, coeliac disease
, normal pressure hydrocephalus
and cerebellitis.
, episodic ataxia
, and dentatorubropallidoluysian atrophy, as well as autosomal recessive disorders such as Friedreich's ataxia
(sensory and cerebellar, with the former predominating) and Niemann Pick disease, ataxia-telangiectasia (sensory and cerebellar, with the latter predominating), and abetalipoproteinaemia. An example of X-linked ataxic condition is the rare fragile X-associated tremor/ataxia syndrome
.
is a malformation of the brain
. It consists of a downward displacement of the cerebellar tonsils and the medulla
through the foramen magnum, sometimes causing hydrocephalus
as a result of obstruction of cerebrospinal fluid
outflow.
is an autosomal-recessive gene disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete copper from the body. Copper accumulates in the nervous system and liver and can cause ataxia as well as other neurological and organ impairments.
or a benign tumour), compared to those who have a neurological degenerative condition. A review of the management of degenerative ataxia was published in 2009.
The movement disorders associated with ataxia can be managed by pharmacological treatments and through physical therapy
and occupational therapy
to reduce disability
. Some drug treatments that have been used to control ataxia include: 5-hydroxytryptophan (5-HTP), idebenone, amantadine
, physostigmine, L-carnitine or derivatives, trimethoprim–sulfamethoxazole, vigabatrin, phosphatidylcholine, acetazolamide
, 4-aminopyridine, buspirone, and a combination of coenzyme Q10 and vitamin E
. Physical therapy
requires a focus on adapting activity and facilitating motor learning
for retraining specific functional motor patterns. Gait, coordination, and balance training are large components of therapy. Training will likely need to be intense and focused -- as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining. Their therapy consisted of constraint-induced movement therapy
which resulted in improvements of their arm function. Treatment will likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of balance
or poor coordination
. Severe ataxia may eventually lead to the need for a wheelchair
.
In order to obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increasing fatigue and poorer movement patterns.
, but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between visual-association cortex and the frontal premotor and motor cortex), and ataxic respiration (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the medulla oblongata
).
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
sign
Neurological sign
A neurological sign is a class of medical signs. Neurological soft signs are minor neurological signs indicating non-specific cerebral dysfunction. Their presence has been documented in cases of schizophrenia.* Focal neurologic signs...
and symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
that consists of gross lack of coordination
Motor coordination
thumb|right|Motor coordination is shown in this animated sequence by [[Eadweard Muybridge]] of himself throwing a diskMotor coordination is the combination of body movements created with the kinematic and kinetic parameters that result in intended actions. Such movements usually smoothly and...
of muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
that coordinate movement, such as the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
. Several possible causes exist for these patterns of neurological dysfunction. The term "dystaxia" is a rarely-used synonym.
The International Ataxia Awareness Day is observed on September 25 each year.
Cerebellar
The term cerebellar ataxiaCerebellar ataxia
Cerebellar ataxia is a form of ataxia originating in the cerebellum.-References:...
is used to indicate ataxia that is due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits, such as antagonist hypotonia
Hypotonia
Hypotonia is a state of low muscle tone , often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength...
, asynergy
Asynergy
Asynergy is defective or lack of co-ordination between organs, muscles, limbs or joints, resulting in a loss in movement or speed. Asynergy is most likely to occur during complex movements, where several individual muscle contractions are needed to act in unison. Asynergy may be caused by...
, dysmetria
Dysmetria
Dysmetria refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye...
, dyschronometria
Dyschronometria
Dyschronometria is the medical term to describe a patient who is unable to accurately estimate the amount of time that has passed. This can be a sign of cerebellar ataxia....
, and dysdiadochokinesia
Dysdiadochokinesia
Dysdiadochokinesia, dysdiadochokinesis, dysdiadokokinesia, dysdiadokokinesis, or DDK is the medical term for an inability to perform rapid, alternating movements.-Causes:It is a feature of cerebellar ataxia, and is the result of lesions to the cerebellar hemispheres, the posterior or...
. How and where these abnormalities manifest themselves depends on which cerebellar structures have been damaged, and whether the lesion is bilateral or unilateral.
- Dysfunction of the vestibulocerebellum impairs the balance and the control of eye movements. This presents itself with postural instability, in which the person tends to separate his/her feet upon standing, in order to gain a wider base and to avoid titubation (bodily oscillations tending to be forward-backward ones). The instability is therefore worsened when standing with the feet together, regardless of whether the eyes are open or closed. This is a negative Romberg's testRomberg's testRomberg's test or the Romberg maneuver is a test used by doctors in a neurological examination, and also as a test for drunken driving. The exam is based on the premise that a person requires at least two of the three following senses to maintain balanced while standing:Proprioception ; Vestibular...
, or more accurately, it denotes the individual's inability to carry out the test, because the individual feels unstable even with open eyes. - Dysfunction of the spinocerebellum presents itself with a wide-based "drunken sailor" gait (called truncal ataxia), characterised by uncertain starts and stops, lateral deviations, and unequal steps.
- Dysfunction of the cerebrocerebellum presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia). These include:
- intention tremorIntention tremorIntention tremor, also known as cerebellar tremor, is a dyskinetic disorder characterized by a broad, course, and low frequency tremor. The amplitude of an intention tremor increases as an extremity approaches the endpoint of deliberate and visually guided movement...
(coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes as well as the limbs and torso); - peculiar writing abnormalities (large, unequal letters, irregular underlining);
- a peculiar pattern of dysarthriaDysarthriaDysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
(slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm). - inability to perform rapidly alternating movements, known as dysdiadochokinesiaDysdiadochokinesiaDysdiadochokinesia, dysdiadochokinesis, dysdiadokokinesia, dysdiadokokinesis, or DDK is the medical term for an inability to perform rapid, alternating movements.-Causes:It is a feature of cerebellar ataxia, and is the result of lesions to the cerebellar hemispheres, the posterior or...
. This could involve rapidly switching from pronationPronationIn anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar and talocalcaneonavicular joints. For the forearm, when standing in the anatomical position, pronation will move the palm of the hand from an anterior-facing position to a...
to supinationSupinationSupination is a position of either the forearm or foot; in the forearm when the palm faces anteriorly, or faces up . Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the anterior of their feet.The hand is supine in the anatomical position...
of the forearm. Movements become more irregular with increases of speed. - inability to judge distances or ranges of movement. This is known is dysmetriaDysmetriaDysmetria refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye...
and is often seen as undershooting, hypometria, or overshooting, hypermetria, the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someone's finger or touch their own nose. - the rebound phenomenon, also known as the loss of the check reflex is also sometimes seen in patients with cerebellar ataxia. For example, when a patient is flexing their elbow isometrically against a resistance. When the resistance is suddenly removed without warning, the patient's arm may swing up and even strike themselves. With an intact check reflex, the patient will check and activate the opposing triceps to slow and stop the movement.
- intention tremor
Sensory
The term sensory ataxiaSensory ataxia
Sensory ataxia is both a symptom and a sign in neurology. It is a form of ataxia caused not by cerebellar dysfunction but by loss of sensory input into the control of movement....
is employed to indicate ataxia due to loss of proprioception
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
, the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the dorsal columns of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain which receive positional information, including the cerebellum, thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, and parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
s.
Sensory ataxia presents itself with an unsteady "stomping" gait with heavy heel
Heel
In human anatomy, the heel is the prominence at the posterior end of the foot. It is based on the projection of one bone, the calcaneus or heel bone, behind the articulation of the bones of the lower leg.- Human anatomy :...
strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by visual input
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
, such as in poorly lit environments.
Physicians can find evidence of sensory ataxia during physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
by having the patient stand with his/her feet together and eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall. This is called a positive Romberg's test
Romberg's test
Romberg's test or the Romberg maneuver is a test used by doctors in a neurological examination, and also as a test for drunken driving. The exam is based on the premise that a person requires at least two of the three following senses to maintain balanced while standing:Proprioception ; Vestibular...
. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when the patient is standing with arms and hands extended toward the physician, if the eyes are closed, the patient's finger will tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").
Vestibular
The term vestibular ataxia is employed to indicate ataxia due to dysfunction of the vestibular systemVestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
, which in acute and unilateral cases is associated with prominent vertigo
Vertigo (medical)
Vertigo is a type of dizziness, where there is a feeling of motion when one is stationary. The symptoms are due to a dysfunction of the vestibular system in the inner ear...
, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
and vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and dysequilibrium may be the sole presentation.
Causes
The three types of ataxia have overlapping causes, and therefore can either coexist or occur in isolation.Focal lesions
Any type of focal lesion of the central nervous systemCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(such as stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, brain tumour, multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
) will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum, sensory if in the dorsal spinal cord (and rarely in the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
or parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
), vestibular if in the vestibular system (including the vestibular areas of the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
).
Exogenous substances
Exogenous substances that cause ataxia mainly do so because they have a depressant effect on central nervous system function. The most common example is ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, which is capable of causing reversible cerebellar and vestibular ataxia. Other examples include various prescription drugs (e.g. most antiepileptic drugs have cerebellar ataxia as a possible adverse effect
Adverse effect (medicine)
In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...
), Lithium level over 1.5mEq/L, cannabis
Cannabis
Cannabis is a genus of flowering plants that includes three putative species, Cannabis sativa, Cannabis indica, and Cannabis ruderalis. These three taxa are indigenous to Central Asia, and South Asia. Cannabis has long been used for fibre , for seed and seed oils, for medicinal purposes, and as a...
ingestion and various other recreational drugs (e.g. ketamine
Ketamine
Ketamine is a drug used in human and veterinary medicine. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA receptor antagonist...
, PCP
Phencyclidine
Phencyclidine , commonly initialized as PCP and known colloquially as angel dust, is a recreational dissociative drug...
or dextromethorphan
Dextromethorphan
Dextromethorphan is an antitussive drug. It is one of the active ingredients in many over-the-counter cold and cough medicines, such as Robitussin, NyQuil, Dimetapp, Vicks, Coricidin, Delsym, and others, including generic labels. Dextromethorphan has also found other uses in medicine, ranging...
, all of which are NMDA receptor antagonist
NMDA receptor antagonist
NMDA receptor antagonists are a class of anesthetics that work to antagonize, or inhibit the action of, the N-methyl d-aspartate receptor . They are used as anesthesia for animals and, less commonly, for humans; the state of anesthesia they induce is referred to as dissociative anesthesia...
s that produce a dissociative state at high doses). Exposure to high levels of methylmercury
Methylmercury
Methylmercury is an organometallic cation with the formula . It is a bioaccumulative environmental toxicant.-Structure:...
, through consumption of fish with high mercury concentrations, is also a known cause of ataxia and other neurological disorders
Radiation poisoning
Ataxia can be induced as a result of severe acute radiation poisoning with an absorbed dose of more than 30 Grays.Vitamin B12 deficiency
Vitamin B12Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
deficiency
Vitamin B12 deficiency
Vitamin B12 deficiency or hypocobalaminemia is a low blood level of vitamin B12, it can cause permanent damage to nervous tissue as a long term effect. Vitamin B12 was discovered from its relationship to the disease pernicious anemia, which is an autoimmune disease that destroys parietal cells in...
may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.
Causes of isolated sensory ataxia
Peripheral neuropathiesPeripheral neuropathy
Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....
may cause generalised or localised sensory ataxia (e.g. a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.
Non-hereditary cerebellar degeneration
Non-hereditary causes of cerebellar degeneration include chronic ethanol abuse, paraneoplastic cerebellar degenerationParaneoplastic cerebellar degeneration
Paraneoplastic cerebellar degeneration is a paraneoplastic syndrome associated with lung, ovarian, breast, and other cancers.As is the case with other paraneoplastic syndromes, PCD is believed to be due to an autoimmune reaction targeted against components of the central nervous system...
, high altitude cerebral oedema, coeliac disease
Coeliac disease
Coeliac disease , is an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward...
, normal pressure hydrocephalus
Normal pressure hydrocephalus
Normal pressure hydrocephalus , also termed symptomatic hydrocephalus, occurs when there is an increase in intracranial pressure due to an abnormal accumulation of cerebrospinal fluid in the ventricles of the brain, which can cause ventriculomegaly...
and cerebellitis.
Hereditary ataxias
Ataxia may depend on hereditary disorders consisting of degeneration of the cerebellum and/or of the spine; most cases feature both to some extent, and therefore present with overlapping cerebellar and sensory ataxia, even though one is often more evident than the other. Hereditary disorders causing ataxia include autosomal dominant ones such as spinocerebellar ataxiaSpinocerebellar ataxia
Spinocerebellar ataxia is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a disease in its own right.-Classification:...
, episodic ataxia
Episodic ataxia
Episodic ataxia is an autosomal dominant disorder characterized by sporadic bouts of ataxia with or without myokymia . There are seven types recognised but the majority are due to two recognized entities. Ataxia can be provoked by stress, startle, or heavy exertion such as exercise. Symptoms can...
, and dentatorubropallidoluysian atrophy, as well as autosomal recessive disorders such as Friedreich's ataxia
Friedreich's ataxia
Friedreich's ataxia is an inherited disease that causes progressive damage to the nervous system, resulting in symptoms ranging from gait disturbance to speech problems; it can also lead to heart disease and diabetes....
(sensory and cerebellar, with the former predominating) and Niemann Pick disease, ataxia-telangiectasia (sensory and cerebellar, with the latter predominating), and abetalipoproteinaemia. An example of X-linked ataxic condition is the rare fragile X-associated tremor/ataxia syndrome
Fragile X-associated tremor/ataxia syndrome
Fragile X-associated tremor/ataxia syndrome is a late onset neurodegenerative disorder associated with problems with movement, memory, and the autonomic nervous system...
.
Arnold-Chiari malformation
Arnold-Chiari malformationArnold-Chiari malformation
Arnold–Chiari malformation, or often simply Chiari malformation, is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils through the foramen magnum , sometimes causing non-communicating hydrocephalus as a result of obstruction of cerebrospinal fluid outflow...
is a malformation of the brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
. It consists of a downward displacement of the cerebellar tonsils and the medulla
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
through the foramen magnum, sometimes causing hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
as a result of obstruction of cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
outflow.
Wilson's Disease
Wilson's DiseaseWilson's disease
Wilson's disease or hepatolenticular degeneration is an autosomal recessive genetic disorder in which copper accumulates in tissues; this manifests as neurological or psychiatric symptoms and liver disease...
is an autosomal-recessive gene disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete copper from the body. Copper accumulates in the nervous system and liver and can cause ataxia as well as other neurological and organ impairments.
Treatment
The treatment of ataxia and its effectiveness depend on the underlying cause. Treatment may limit or reduce the effects of ataxia, but it is unlikely to eliminate them entirely. Recovery tends to be better in individuals with a single focal injury (such as strokeStroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
or a benign tumour), compared to those who have a neurological degenerative condition. A review of the management of degenerative ataxia was published in 2009.
The movement disorders associated with ataxia can be managed by pharmacological treatments and through physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
and occupational therapy
Occupational therapy
Occupational therapy is a discipline that aims to promote health by enabling people to perform meaningful and purposeful activities. Occupational therapists work with individuals who suffer from a mentally, physically, developmentally, and/or emotionally disabling condition by utilizing treatments...
to reduce disability
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...
. Some drug treatments that have been used to control ataxia include: 5-hydroxytryptophan (5-HTP), idebenone, amantadine
Amantadine
Amantadine is the organic compound known formally as 1-adamantylamine or 1-aminoadamantane. The molecule consists of adamantane backbone that has an amino group substituted at one of the four methyne positions. This pharmaceutical is sold under the name Symmetrel for use both as an antiviral and an...
, physostigmine, L-carnitine or derivatives, trimethoprim–sulfamethoxazole, vigabatrin, phosphatidylcholine, acetazolamide
Acetazolamide
Acetazolamide, sold under the trade name Diamox, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, Idiopathic intracranial hypertension , altitude sickness, cystinuria, and dural ectasia...
, 4-aminopyridine, buspirone, and a combination of coenzyme Q10 and vitamin E
Vitamin E
Vitamin E is used to refer to a group of fat-soluble compounds that include both tocopherols and tocotrienols. There are many different forms of vitamin E, of which γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings...
. Physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
requires a focus on adapting activity and facilitating motor learning
Motor learning
Motor learning is a “relatively permanent” change, resulting from practice or a novel experience, in the capability for responding...
for retraining specific functional motor patterns. Gait, coordination, and balance training are large components of therapy. Training will likely need to be intense and focused -- as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining. Their therapy consisted of constraint-induced movement therapy
Constraint-induced movement therapy
Constraint-induced movement therapy is a form of rehabilitation therapy that improves upper extremity function in stroke and other Central Nervous System damage victims by increasing the use of their affected upper limb....
which resulted in improvements of their arm function. Treatment will likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of balance
Balance
- Equipment :* Balance beam, a piece of gymnastics apparatus.* Balance board, a piece of training equipment.* Balancing machine, a machine that balances mechanical rotating parts to lessen vibration.* Balance wheel, a watch component....
or poor coordination
Coordination
Coordination is the act of coordinating, making different people or things work together for a goal or effect to fulfill desired goals in an organization.Coordination is a managerial function in which different activities of the business are properly adjusted and interlinked.Coordination may also...
. Severe ataxia may eventually lead to the need for a wheelchair
Wheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...
.
In order to obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increasing fatigue and poorer movement patterns.
Other uses of the term
The term "ataxia" is sometimes used in a broader sense to indicate lack of coordination in some physiological process. Examples include optic ataxia (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects. Optic ataxia may be caused by lesions to the posterior parietal cortex. The posterior parietal cortex is responsible for combining and expressing positional information and relating it to movement. Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention. Optic ataxia is usually part of Balint's syndromeBalint's syndrome
Bálint's syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole , difficulty in fixating the eyes , and inability to move the hand to a specific object by using vision...
, but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between visual-association cortex and the frontal premotor and motor cortex), and ataxic respiration (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the medulla oblongata
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
).
External links
- Ataxia UK Charity
- Brasil, Rio Grande do Sul - Associação dos Amigos, Parentes e Portadores de Ataxias Dominantes
- University of Minnesota Ataxia Center
- Ataxia Connect Social Network
- Overview at National Institute of Neurological Disorders and StrokeNational Institute of Neurological Disorders and StrokeThe National Institute of Neurological Disorders and Stroke is a part of the U.S. National Institutes of Health . It conducts and funds research on brain and nervous system disorders and has a budget of just over US$1.5 billion...
(NINDS) - US National Ataxia Foundation
- Ataxia UK, including guidelines
- GeneReview/NIH/UW entry on Hereditary Ataxia Overview
- International Ataxia Awareness Day
- Ataxia Forums
- LivingWithAtaxia Forums & Community
- Canadian Association for Familial Ataxias - Claude St-Jean Foundation
- The latest news and research on Ataxia
- Video from the US Department of Agriculture of a sheep with scrapieScrapieScrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies , which are related to bovine spongiform encephalopathy and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie...
- GeneReview/NIH/UW entry on Hereditary Ataxia Overview