What is Ataxia?

WHAT IS ATAXIA?

The word ‘ataxia’ comes from the Greek word ‘ataxis’ meaning ‘without order’ or ‘incoordination’. Ataxia can be a symptom of many disorders, including those associated with infections, injuries, or degenerative changes in the central nervous system. However, we are concerned with the hereditary ataxia’s, a special group of inherited diseases which have in common that they cause degeneration of the cerebellum (the ‘coordination center’ of the brain) or it’s pathways.

What Causes Hereditary Ataxia?

The hereditary ataxias are genetic, which means they are caused by a defect in a certain gene present at the beginning of a person’s life. All of us have genes that have little mistakes or variations in them. Most variations do not cause disease. Occasionally, however, variations are significant enough to cause disease, including ataxia.. Disease causing variations are called mutations.

What are common symptoms?

Symptoms and time of onset vary according to the type of ataxia. Recessive disorders commonly cause symptoms to begin in childhood rather than adulthood (although for reasons that are not understood, symptoms are not necessarily present at birth or in infancy). Dominate ataxia begins in the 20’s or 30’s or even later in life. Occasionally, individuals may not show symptoms until they are in their 60’s.

Typically, balance and coordination are affected first. Incoordination of hands, arms and legs, and slurring of speech are other common symptoms. Walking becomes difficult and is characterized by walking with the feet placed farther apart to compensate for poor balance. Impaired coordination of the arms affects the person’s ability to perform task requiring fine motor control such as writing or eating. Slow eye movements or limited range of eye movements can be seen in some forms of ataxia. As time goes on, ataxia can affect speech and swallowing.

The hereditary ataxias are degenerative disorders that 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. Respiratory complications can be fatal in a person who is bed-bound or who has severe swallowing problems. Some children with Friedreich’s ataxia develop serious cardiac complications.

How Is Hereditary Ataxia Diagnosed?

Diagnosis is based on a person’s medical history, family history and a complete neurological evaluation including an MRI scan of the brain. Various blood test may be performed to rule out other possible disorders which may present similar symptoms. Genetic blood test have been developed to diagnose some specific form of ataxia. The symptoms of the different hereditary ataxias often overlap, and only a gene test can tell for sure if a person has SCA1 (spinocerebellar ataxia type 1) or one of the other spinocerebellar ataxias (including SCA2, 3, 6, 7, 8, 10, 11 or 12). Since not all of the abnormal genes that cause ataxia have been discovered, it is also possible to have hereditary ataxia even though all the gene tests are normal.