Types of Ataxia
The word ataxia means ‘loss of full control of bodily movements.’ It occurs when parts of the nervous system are damaged. Ataxia is a symptom of an underlying problem, but the term is also used to describe a group of degenerative diseases of the nervous system, many of which are inherited. There are many different types of ataxia, each with different symptoms and causes. Learn more about different ataxia types, including Friedreich’s ataxia, ataxia telangiectasia, spinocerebellar ataxia, and cerebellar ataxia.
Friedreich’s ataxia is the most common hereditary ataxia in the United States, affecting approximately 1 in every 50,000 people. In order to develop Friedreich’s ataxia, a person must have inherited two abnormal copies of a specific gene (the FXN gene), one from their mother and one from their father.
Symptoms of Friedreich’s ataxia usually begin in childhood, between the ages of 5 to 15 years. Only about 15% of people with Friedreich’s ataxia first develop symptoms after age 25. Early symptoms include loss of sensation in the arms and legs, difficulty walking, and poor balance. Slowed, slurred speech is another symptom of ataxia. Over time, muscle weakness increases, and affected individuals may experience involuntary, spastic movements.
Eventually, individuals develop hearing and vision problems and difficulty swallowing. Up to two-thirds of people with Friedreich’s ataxia develop scoliosis, and approximately one-third develop diabetes. Some people develop heart problems as well.
The rate of progression of the disease varies. Most people with Friedreich’s ataxia need a wheelchair within 10 to 20 years of when symptoms start. Life expectancy is shorter than what is typical for men and women; some people with this form of ataxia live into their 60s, but many pass away sooner. Heart disease is a common cause of death.
Ataxia telangiectasia (A-T) is a rare form of ataxia that affects children. It is an inherited disease that affects approximately 1 out of 40,000 to 1 out of 100,000 persons worldwide.
Children with A-T appear normal at birth. Symptoms usually develop during the toddler years and become apparent as children learn to walk. Toddlers with A-T tend to sway or wobble when walking, sitting, or standing still, and their balance becomes progressively worse over time, instead of better. By school-age, children usually have difficulty controlling their eye movements and develop slurred speech and swallowing problems.
A visible hallmark of A-T are telangiectasias, or tiny red spider veins that appear at the corners of the eyes or where the ears and cheeks are exposed to the sun.
Unfortunately, A-T increases the risk of other health complications. Approximately 70% of children with A-T have weakened immune systems and are particularly prone to lung infections. Children with A-T are also 1000X more likely than healthy children to develop a blood cancer; A-T also increases the body’s sensitivity to radiation, so it’s difficult to treat their cancers.
By age 10, most children with A-T are dependent on wheelchairs and unable to write or read. Speech is also difficult and slurred.
Most people with A-T live into their late teens or twenties; a few people survive until their 40s or 50s.
Spinocerebellar ataxias (SCAs) are a group of hereditary ataxias that typically begin in adulthood.
Spinocerebellar ataxia type 1 (SCA1) affects 1 to 2 people per 100,000 worldwide. Symptoms of SCA1 include difficulty with balance and coordination, speech, and swallowing, as well as uncontrolled rapid eye movements. In time, affected individuals may develop numbness, tingling, and involuntary movements. Most people with SCA1 live 10 to 20 years after the appearance of symptoms.
Spinocerebellar ataxia type 3 (SCA3) is also called Machado-Joseph disease (MJD). This disease is most common in people of Portuguese/Azorean descent.
Cerebellar ataxia, also known as cerebellar ataxia syndrome, is an acquired type of ataxia that results from injury to the cerebellum, the part of the brain that controls movement. This type of ataxia is not inherited. Instead, it can be caused by a stroke; exposure to alcohol, illicit drugs, or insecticides; bleeding; multiple sclerosis; head trauma; or a viral infection, including chickenpox infection.
The symptoms of cerebellar ataxia include clumsy speech and movement and repetitive eye movements.
If a viral infection causes ataxia, full recovery usually occurs within several months. In other cases, ataxia is progressive, worsening with time.
Currently, there is no cure for hereditary ataxias and ongoing cerebellar ataxias. Treatment focuses on symptom control and comfort (supportive measures). Physical therapy, speech therapy, and occupational therapy, along with assistive devices can help the affected individual function independently. However, people with progressive ataxia become dependent on caregivers in later stages.