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.