Ataxia (from Greek - [a negative prefix] + - [order] = "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that includes gait abnormality. 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. Dystaxia is a mild degree of ataxia. Friedrich's ataxia has gait abnormality as the most common presenting symptom.[1]

The term cerebellar ataxia is used to indicate ataxia that is due to dysfunction of the cerebellum. The cerebellum is responsible for integrating a significant amount of neural information that is used to coordinate smoothly ongoing movements and to participate in motor planning. Although ataxia is not present with all cerebellar lesions, many conditions affecting the cerebellum do produce ataxia.[2] People with cerebellar ataxia may have trouble regulating the force, range, direction, velocity and rhythm of muscle contractions.[3] This results in a characteristic type of irregular, uncoordinated movement that can manifest itself in many possible ways, such as asthenia, asynergy, delayed reaction time, and dyschronometria.[citation needed] Individuals with cerebellar ataxia could also display instability of gait, difficulty with eye movements, dysarthria, dysphagia, hypotonia, dysmetria and dysdiadochokinesia.[2] These deficits can vary depending on which cerebellar structures have been damaged, and whether the lesion is bilateral or unilateral.

People with cerebellar ataxia may initially present with poor balance, which could be demonstrated as an inability to stand on one leg or perform tandem gait. As the condition progresses, walking is characterized by a widened base and high stepping, as well as staggering and lurching from side to side.[2] Turning is also problematic and could result in falls. As cerebellar ataxia becomes severe, great assistance and effort are needed to stand and walk.[2]Dysarthria, an impairment with articulation, may also be present and is characterized by "scanning" speech that consists of slower rate, irregular rhythm and variable volume.[2] There may also be slurring of speech, tremor of the voice and ataxic respiration. Cerebellar ataxia could result with incoordination of movement, particularly in the extremities. There is overshooting with finger to nose testing, and heel to shin testing; thus, dysmetria is evident.[2] Impairments with alternating movements (dysdiadochokinesia), as well as dysrhythmia, may also be displayed. There may also be tremor of the head and trunk (titubation) in individuals with cerebellar ataxia.[2]

It is thought that dysmetria is caused by a deficit in the control of interaction torques in multijoint motion.[4] Interaction torques are created at an associated joint when the primary joint is moved. For example, if a movement required reaching to touch a target in front of the body, flexion at the shoulder would create a torque at the elbow, while extension of the elbow would create a torque at the wrist. These torques increase as the speed of movement increases and must be compensated and adjusted for to create coordinated movement. This may, therefore, explain decreased coordination at higher movement velocities and accelerations.

The term sensory ataxia 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 lobes.

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 eyes 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").

The term vestibular ataxia is employed to indicate ataxia due to dysfunction of the vestibular system, 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.

The three types of ataxia have overlapping causes, and therefore can either coexist or occur in isolation.

Any type of focal lesion of the central nervous system (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).

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Ataxia - Wikipedia, the free encyclopedia

Ataxia-telangiectasia is a rare, childhood neurological disorder that causes degeneration in the part of the brain that controls motor movements and speech. The first signs of the disease are unsteady walking and slurred speech, usually occurring during the first five years of life. Telangiectasias (tiny, red "spider" veins), which appear in the corners of the eyes or on the surface of the ears and cheeks, are characteristic of the disease, but are not always present and generally do not appear in the first years of life. About 35 percent of those with A-T develop cancer, most frequently acute lymphocytic leukemia or lymphoma. The most unusual symptom is an acute sensitivity to ionizing radiation, such as X-rays or gamma rays. Many individuals with A-T have a weakened immune system, making them susceptible to recurrent respiratory infections. Other features of the disease may include mild diabetes mellitus, premature graying of the hair, difficulty swallowing, and delayed physical and sexual development. Children with A-T usually have normal or above normal intelligence.

There is no cure for A-T and, currently, no way to slow the progression of the disease. Treatment is symptomatic and supportive. Physical and occupational therapy help to maintain flexibility. Speech therapy is important, teaching children to control air flow to the vocal cords. Gamma-globulin injections may be useful if immunoglobulin levels are sufficiently reduced to weaken the immune system. High-dose vitamin regimens and antioxidants such as alpha lipoic acid also may also be used.

Average lifespan has been improving for years, for unknown reasons, and varies with the severity of the underlying mutations, ATM (ataxia-telangiectasia mutated) protein levels, and residual ATM kinase activity. Some individuals with later onset of disease and slower progression survive into their 50s.

NINDS-supported researchers discovered the gene responsible for A-T, known as ATM (ataxia-telangiectasia mutated) in 1995. This gene makes a protein that activates many (probably more than 700) other proteins that control cell cycle, DNA repair, and cell death. Without it, cells are unable to activate the cellular checkpoints that protect against the damage of ionizing radiation and other agents that can harm DNA. In addition to supporting basic research on A-T, NINDS also funds research aimed at A-T drug development, including development of animal models, gene and stem-cell based therapies, and high-throughput drug screens. The NINDS also leads a trans-NIH A-T Working Group whose members include NINDS, NHLBI, NIEHS, NCI, NEI, NIGMS, NHGRI, NIA, NIAID, NICHD, and ORD.

Prepared by: Office of Communications and Public Liaison National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda, MD 20892

NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.

All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.

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Welcome to the National Ataxia Foundation

As a member you help provide those with ataxia a better life and hope for a brighter tomorrow. NAF is a membership based nonprofit organization dedicated to serving ataxia families. We are grateful for the support of our members and welcome others to also join.

As a thank you for being a valued member, you will receive discounts in attending the annual membership meeting as well as a subscription to the NAFs in-depth quarterly ataxia news publication, Generations.

Be Part of Team NAFbecome a member today! Please ask your friends, family, co-workers, and neighbors to also become a member. Thank you!

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The National Ataxia Foundation (NAF) is pleased to announce that 23 promising ataxia research studies from the United States, Belgium, Mexico, United Kingdom, Portugal, and Germany were awarded funding at the December 2014 NAF Board of Directors meeting for fiscal year 2015. With the funding of these 23 research studies and the previous research studies funded earlier in 2014, nearly one million dollars were committed for ataxia research. Click here for more information.

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Ataxia telangiectasia (A-T) (also referred to as LouisBar syndrome) is a rare, neurodegenerative, inherited disease causing severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease.[1]

A-T affects many parts of the body:

Symptoms most often first appear in early childhood (the toddler stage) when children begin to walk. Though they usually start walking at a normal age, they wobble or sway when walking, standing still or sitting, and may appear almost as if they are drunk. In late pre-school and early school age they develop difficulty moving the eyes in a natural manner from one place to the next (oculomotor apraxia). They develop slurred or distorted speech, and swallowing problems. Some have an increased number of respiratory tract infections (ear infections, sinusitis, bronchitis, and pneumonia). Because not all children develop in the same manner or at the same rate, it may be some years before A-T is properly diagnosed. Most children with A-T have stable neurologic symptoms for the first 45 years of life, but begin to show increasing problems in early school years.

A-T is caused by a defect in the ATM gene,[2] which is responsible for managing the cells response to multiple forms of stress including double-strand breaks in DNA. In simple terms, the protein produced by the ATM gene recognizes that there is a break in DNA, recruits other proteins to fix the break, and stops the cell from making new DNA until the repair is complete.[3]

There is substantial variability in the severity of features of A-T between affected individuals, and at different ages. The following symptoms or problems are either common or important features of A-T:

Many children are initially misdiagnosed as having ataxic cerebral palsy. The diagnosis of A-T may not be made until the preschool years when the neurologic symptoms of impaired gait, hand coordination, speech and eye movement appear or worsen, and the telangiectasia first appear. Because A-T is so rare, doctors may not be familiar with the symptoms, or methods of making a diagnosis. The late appearance of telangiectasia may be a barrier to the diagnosis. It may take some time before doctors consider A-T as a possibility because of the early stability of symptoms and signs.

The first indications of A-T usually occur during the toddler years.[4][5] Children start walking at a normal age, but may not improve much from their initial wobbly gait. Sometimes they have problems standing or sitting still and tend to sway backward or from side to side. In primary school years walking becomes more difficult, and children will use doorways and walls for support. Children with A-T often appear better when running or walking quickly in comparison to when they are walking slowly or standing in one place. Around the beginning of their second decade children with typical forms of A-T start using a wheelchair for long distances. During school years children may have increasing difficulty with reading because of impaired coordinating of eye movement. At the same time other problems with fine motor functions (writing, coloring, and using utensils to eat), and with slurring of speech (dysarthria) may arise. Most of these neurologic problems stop progressing after the age of about 12 15 years, though involuntary movements may start at any age and may worsen over time. These extra movements can take many forms, including small jerks of the hands and feet that look like fidgeting (chorea), slower twisting movements of the upper body (athetosis), adoption of stiff and twisted postures (dystonia), occasional uncontrolled jerks (myoclonic jerks), and various rhythmic and non-rhythmic movements with attempts at coordinated action (tremors).

Prominent blood vessels (telangiectasia) over the white (sclera) of the eyes usually occur by the age of 58 years, but sometimes later or not at all.[6] The absence of telangiectasia does not exclude the diagnosis of A-T. Potentially a cosmetic problem, the ocular telangiectasia do not bleed or itch, though they are sometimes misdiagnosed as chronic conjunctivitis. It is their constant nature, not changing with time, weather or emotion, that marks them as different from other visible blood vessels. Telangiectasia can also appear on sun-exposed areas of skin, especially the face and ears. They occur in the bladder as a late complication of chemotherapy with cyclophosphamide, have been seen deep inside the brain of older people with A-T, and occasionally arise in the liver and lungs.

About two-thirds of people with A-T have abnormalities of the immune system.[7] The most common abnormalities are low levels of one or more classes of immunoglobulins (IgG, IgA, IgM or IgG subclasses), not making antibodies in response to vaccines or infections, and having low numbers of lymphocytes (especially T-lymphocytes) in the blood. Some people have frequent infections of the upper (colds, sinus and ear infections) and lower (bronchitis and pneumonia) respiratory tract. All children with A-T should have their immune systems evaluated to detect those with severe problems that require treatment to minimize the number or severity of infections. Some people with A-T need additional immunizations (especially with pneumonia and influenza vaccines), antibiotics to provide protection (prophylaxis) from infections, and/or infusions of immunoglobulins (gamma globulin). The need for these treatments should be determined by an expert in the field of immunodeficiency or infectious diseases.

People with A-T have a highly increased incidence (approximately 25% lifetime risk) of cancers, particularly lymphomas and leukemia, but other cancers can occur.[8] When possible, treatment should avoid the use of radiation therapy and chemotherapy drugs that work in a way that is similar to radiation therapy (radiomimetic drugs), as these are particularly toxic for people with A-T. The special problems of managing cancer are sufficiently complicated that treatment should be done only in academic oncology centers and after consultation with physicians who have specific expertise in A-T. Unfortunately, there is no way to predict which individuals will develop cancer. Because leukemia and lymphomas differ from solid tumors in not progressing from solitary to metastatic stages, there is less need to diagnose them early in their appearance. Surveillance for leukemia and lymphoma is thus not helpful, other than considering cancer as a diagnostic possibility whenever possible symptoms of cancer (e.g. persistent swollen lymph glands, unexplained fever) arise.

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