Ataxia, what is it?

Ataxia is not a disease in itself, but a symptom which results from damage to the cerebellum (the part of the brain that controls the coordination of muscles).

Ataxia consists of loss of coordination in the muscles of the arms and legs during voluntary movements such as walking or gripping objects. Ataxia can also affect the passwords, the eye movements andability to swallow. Ataxia is also called cerebellar ataxia or cerebellar syndrome.

There are also several variations ofataxies hereditary. These are neurological and genetic diseases that affect the cerebellum. They are most of the time degenerative, that is to say that the coordination problems become more pronounced over time.

Causes

Ataxia can be caused by multiple conditions:

• Un head trauma. Damage caused to the spine or the brain as a result of a traffic accident, for example.
• A cerebrovascular accident (stroke) or transient ischemic attack (TIA or mini-stroke), that is to say the temporary obstruction of a cerebral artery which resolves naturally, without leaving any after-effects.
• A cerebral palsy. Damage to the brain before, during or very soon after birth that affects the coordination of movements.
• Complications following a viral infection such as chickenpox or the Epstein-Barr virus.
• Multiple sclerosis.
• A toxic reaction to heavy metals, such as lead or mercury or solvents.
• A reaction to certain medications, such as barbituriques (for example phenobarbital) or sedatives (eg benzodiazepines), used to treat anxiety, agitation or insomnia.
• Drug or alcohol abuse.
• Metabolic disorders.
• Vitamin deficiency.
• A tumor, cancerous or benign that affects the cerebellum.

Dominant hereditary ataxias are caused by a gene from a single parent.

For example:

• THEspinocerebellar ataxia. There are approximately 36 variants (designated SCA1 to SCA30) of the disease, characterized by different ages of onset and different organs affected in addition to the cerebellum (eg the eye).
• THEataxia episodic. There are 7 types of episodic ataxias (designated EA1 to EA7) which manifest as acute attacks affecting balance and coordination.

Hereditary recessive ataxias are caused by a gene from both parents.

For example:

• THEataxia de Friedreich.

This inherited progressive neuromuscular disease causes decreased energy production in the body. Nerve and heart cells are the most affected. People with abnormal gait, clumsiness and one speech disorder, which appears in childhood or early adolescence. These abnormalities lead to skeletal changes, such as twisting of the spine (scoliosis), distortion of the feet, as well as enlargement of the heart. In Europe, around 1 in 50 people are thought to have the disease. In France, there are around 000 patients.

• THEataxia spastic Charlevoix-Saguenay (ARSACS).

This rare hereditary disease is specific to people from the Saguenay-Lac-St-Jean and Charlevoix regions in Quebec. It results in a spinal cord degeneration, accompanied by progressive damage to the peripheral nerves. About 250 people are affected by this disease in the affected areas. About 1 in 22 people carry the ARSACS gene in these areas.

• L’ataxia telangiectasia or Louis-Bar Syndrome.

This rare genetic disease affects the locomotion, the blood vessels (dilation) and the immune system. The disease usually appears at the age of 1 or 2 years. Its frequency is estimated to be around 1 in 40 to 000 births worldwide.

It can also sometimes happen that neither parent suffers from the disease and in this case there is no obvious family history (silent mutation).