What is ataxia?

The word "ataxia" comes from the Greek word "a taxis," which means "without order or without coordination." Thus, ataxia means without coordination.

Persons who are diagnosed with ataxia experience a failure of muscle control in their arms and legs which may result in a lack of balance, coordination, and possibly a disturbance in gait. Ataxia may affect the fingers, hands, arms, legs, body, speech, and even eye movements.

The word ataxia is often used to describe the symptom of incoordination that may accompany infections, injuries, other diseases, and/or degenerative changes in the central nervous system. The symptom of ataxia can be caused by stroke, multiple sclerosis, tumors, alcoholism, peripheral neuropathy, metabolic disorders, and vitamin deficiencies. in these cases, treating the condition that caused ataxia my improve it.

While the term ataxia usually describes symptoms, it also describes a group of specific degenerative diseases of the central nervous system called the hereditary and sporadic ataxias. The remainder of this article discusses these disorders.

What causes ataxia?

Most disorders that result in ataxia are found to have degeneration, or atrophy, of the cells in the part of the brain called the cerebellum. The cerebellum is located at the back of the head. Its function is to coordinate voluntary muscle movements and to maintain posture, balance, and equilibrium.

The spine can also be affected. The terms cerebellar degeneration and spinocerebellar degeneration may be used to refer to this type of damage to the nervous system. 

The various abnormal genes that cause ataxia do have something in common: they make abnormal proteins that affect nerve cells, primarily in the cerebellum and in the spinal cord. They may also affect other parts of the brain.

The affected nerve cells begin to function poorly and ultimately degenerate. As the disease progresses, muscles become less and less responsive to the commands of the brain. This causes balance and coordination to become a greater problem.

Types of ataxia

As discussed above, there are two types of ataxia:

  • Sporadic ataxias

    Ataxias of this type usually begin in adulthood and have no known family history.

  • Hereditary ataxias

    These ataxias are caused by a defect in a gene that is present from the start of a person's life and can be either dominantly inherited or recessively inherited. Recessive disorders commonly cause symptoms to begin in childhood rather than in adulthood.

    Genetic testing is now available. Friedreich's ataxia is recessively inherited and occurs in childhood, but can have an adult onset in up to one third of patients. Dominant ataxia often begins in the twenties or thirties or sometimes even later in life.

    Hereditary ataxias are degenerative disorders that may progress over a number of years. How severe the disability depends on the type of ataxia, the age of onset of symptoms, and other factors that are poorly understood.

What are common symptoms of ataxia?

Symptoms and time of onset may vary according to the type of ataxia. Each individual may experience symptoms differently.

Typically the most common are listed below:

  • Balance and coordination are affected first

  • Incoordination of hands, arms, and legs

  • Slurring of speech

  • Wide-based gait

  • Difficulty with writing and eating

  • Slow eye movements

The symptoms of ataxia may resemble other conditions or medical problems. Always consult your physician for a diagnosis.

How is ataxia diagnosed?

In addition to a thorough medical history, family history, and complete neurological and physical examination, the following diagnostic procedures may be performed:

  • Laboratory tests (including blood and urine studies)

  • Magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and  a computer to produce detailed images of organs and structures within the body

  • Genetic testing - tests performed to determine if a person has certain gene changes (mutations) or chromosome changes which are known to increase risk for certain inherited conditions

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