Ataxia

Definition:
Ataxia (from Greek , meaning “lack of order”) is a neurological sign and symptom consisting of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of 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 rarely used as a synonym.

A sign of an underlying condition, ataxia can affect your movements, your speech, your eye movements and your ability to swallow.
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Persistent ataxia usually results from damage to your cerebellum — the part of your brain that controls muscle coordination. Many conditions may cause ataxia, including alcohol abuse, stroke, tumor, cerebral palsy and multiple sclerosis. It’s also possible to inherit a defective gene that may cause one of many ataxia variants.

Types of ataxia:-

#Cerebellar ataxia:
The term cerebellar ataxia is employed to indicate ataxia 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 depend on which cerebellar structures are lesioned, and whether the lesion is bilateral or unilateral.

*Dysfunction of the vestibulocerebellum impairs balance and control of eye movements. This presents with postural instability, in which the person tends to separate the feet on standing to gain a wider base and avoid oscillations (especially posterior-anterior ones); instability is therefore worsened when standing with the feet together (irrespective of whether the eyes are open or closed: this is a negative Romberg’s test, or more accurately, denotes the inability to carry out the test as the individual is unstable even with open eyes).

*Dysfunction of the spinocerebellum presents with a wide-based “drunken sailor” gait, characterised by uncertain start and stop, lateral deviations, and unequal steps. This part of the cerebellum regulates body and limb movements.

*Dysfunction of the cerebrocerebellum presents with disturbances in carrying out voluntary, planned movements, including intention tremor (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), and a peculiar pattern of dysarthria (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm).

#Sensory ataxia:
The term sensory ataxia is employed to indicate ataxia due to loss of proprioception (sensitivity to joint and body part position), which generally depends on dysfunction of the dorsal columns of the spinal cord, since they carry proprioceptive information up to the brain; in some cases, the cause may instead be dysfunction of the various brain parts that receive that information, including the cerebellum, thalamus, and parietal lobes. Sensory ataxia presents with an unsteady “stomping” gait with heavy heel strikes, as well as postural instability that is characteristically worsened when the lack of proprioceptive input cannot be compensated by visual input, such as in poorly lit environments. Doctors can evidence this during physical examination by having the patient stand with his / her feet together and eyes shut, which will cause the patient’s instability to markedly worsen, 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 examiner, if the eyes are closed, the patient’s finger will tend to “fall down” and be restored to the horizontal extended position by sudden extensor contractions (“ataxic hand”).

#Vestibular ataxia:
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.

Symptoms:-
Symptoms may vary depending on the severity and type of ataxia, of which there are many. If the ataxia is caused by an injury or another health condition, symptoms may emerge at any age, and may well improve and eventually disappear.

Initial ataxia symptoms usually include:
*Poor limb coordination.
*Dysarthria – slurred and slow speech that is difficult to produce. The patient may also have difficulties controlling volume, rhythm, and pitch.

If the ataxia advances other symptoms may also appear:

*Swallowing difficulties, which may sometimes result in choking or coughing.
*Facial expressions become less apparent.
*Tremors – parts of the body may shake or tremble unintentionally.
*Nystagmus – involuntary rapid rhythmic repetitious eye movement. Movements may be vertical, horizontal, or circular.
*Pes cavus – a foot with too high an arch.
*Cold feet – because of a lack of muscle activity.
*Problems with balance.
*Walking difficulties – in severe cases the patient may need a wheelchair.
*Vision problems.
*Hearing problems.
*Depression – as a result of having to live and cope with the symptoms.

Cerebellar ataxias:
Cerebellar ataxia early onset usually emerges between the ages of 4 and 26. Late onset ataxia generally appears after the patient is 20 years old. Late-onset ataxias usually present less severe symptoms, compared to early-onset ataxia.

Ataxia telangiectasia symptoms generally include:
*Small veins appear around the corner of the eyes, cheeks and ears.
*Physical and sexual development is usually delayed.

Friedreich’s ataxia symptoms generally include:
*The spine curves sideways (scoliosis).
*The heart muscle becomes weaker (cardiomyopathy).
*Diabetes.

For patients whose symptoms are caused by injury or illness, symptoms often improve over time, and eventually go away completely.

When to see a doctor:-
If you aren’t aware of having a condition that causes ataxia, such as multiple sclerosis, see your doctor if you:

*Lose balance
*Lose muscle coordination in a hand, arm or leg
*Have difficulty walking
*Slur your speech
*Have difficulty swallowing

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

Focal lesions
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).

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 ethanol, 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), marijuana ingestion[2] and various other recreational drugs (e.g. ketamine, PCP or dextromethorphan, all of which are NMDA receptor antagonists that produce a dissociative state at high doses).

Vitamin B12 deficiency
Vitamin B12 deficiency may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.

Causes of isolated sensory ataxia

Peripheral neuropathies 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 degeneration, high altitude cerebral oedema, coeliac disease, normal pressure hydrocephalus and cerebellitis.

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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 ataxia, 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.

GeneReview/NIH/UW entry on Hereditary Ataxia Overview

Arnold-Chiari Malformation
Arnold-Chiari malformation 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 CSF (cerebrospinal fluid) outflow.

Diagnosis:-
Besides conducting a physical exam and a neurological exam, including checking your memory and concentration, vision, hearing, balance, coordination and reflexes, your doctor may request these laboratory tests:

#Blood tests. Certain blood tests can confirm or exclude the suspected condition. A sample of your blood will be drawn from your arm through a needle. You may be required to fast from midnight the night before your appointment until after your blood is drawn. The specific tests will depend on the suspected cause, but most likely will include a complete blood count (CBC), which helps evaluate your overall health and detect a range of disorders, including infection and heavy metal poisoning.

#Urine tests. Examining a sample of your urine under a microscope (urinalysis) may suggest certain systemic abnormalities that can be related to some forms of ataxia. If your doctor suspects Wilson’s disease, you may be asked for a 24-hour urine collection to help determine the amount of copper in your system.

#Imaging studies. A computerized tomography (CT) scan or magnetic resonance imaging (MRI) of your brain may help determine potential causes.

#Genetic testing. Your doctor may recommend genetic testing to determine whether you or your child has the gene mutation that causes one of the hereditary ataxic conditions. Gene tests are available for many but not all of the hereditary ataxias.

Treatments:-
There’s no treatment specifically for ataxia and it is not curable  but a great deal can be done to ease symptoms and improve the quality of life of the patient. Treatment for coordination and balance problems usually involves the use of adaptive devices which help the patient attain as much independence as possible. These may include the use of a cane (walking stick), crutches, walker or a wheelchair. Symptoms such as tremor, stiffness, spasticity, sleep disorders, muscle weakness, depression (or frustration, sadness and anger) may be addressed with targeted physical therapy, speech therapy, medications and counseling.

Occupational therapy – the occupational therapist can help the patient manage better around the house and work. This may involve some home adaptations, wheelchair assessments, and making the kitchen more practical for the patient.

#Speech therapy – the speech therapist can help with swallowing, coughing, choking and speech problems. If speech becomes very difficult the speech therapist can help the patient learn how to use speech aids.

#Orthopedic care – this can help patients with curvature of the spine (scoliosis).

Physical therapy (physiotherapy) – a physical therapist (physiotherapist) can help maintain strength and improve mobility.

#Physical therapy to help you build strength and enhance your mobility
#Occupational therapy to help you with daily living tasks, such as feeding yourself
#Speech therapy to improve speech and aid swallowing

*Counseling – patients with ataxia commonly become frustrated and depressed; this usually results from having to cope with some symptoms which affect physical mobility and coordination. Talking to a well qualified counselor, such as a psychotherapist can help.

*Supplements and nutrition – some patients with ataxia have very low levels of vitamin E and require supplements and/or a special diet. As sensitivity to gluten is more common among ataxia patients, a gluten-free diet also helps.

*Medication – some patients with ataxia telangiectasia are prescribed gamma-globulin injections to boost their immune systems. There are also drugs for muscle spasms and uncontrollable eye movements.

Coping and support:-
The challenges you face when living with ataxia, such as loss of independence, or having a child with the condition, may make you feel alone or lead to depression and anxiety. Talking to a counselor or therapist may lessen your sense of isolation and help you cope. Or you may find encouragement and understanding in a support group, either for ataxia or for your underlying condition, such as cancer or multiple sclerosis.

Although support groups aren’t for everyone, they can be good sources of information. Group members often know about the latest treatments and tend to share their own experiences. If you’re interested, your doctor may be able to recommend a group in your area.

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, usually part of Balint’s syndrome, 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).

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Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.mayoclinic.com/health/ataxia/DS00910
http://en.wikipedia.org/wiki/Ataxia
http://www.medicalnewstoday.com/articles/162368.php

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