Ataxias (etymologically disorders), also known as cerebellar syndromes, are a group of neurodegenerative diseases of the cerebellum and/or brain stem, which result in problems with the coordination of voluntary movements without muscular weakness, balance and ocular damage. They affect around 1 in 10,000 people in France and most other European countries.
These diseases are due to dysfunctions in neuronal transmission in the cerebellum and in the nerve bundles connected to it. The cerebellum is the part of the brain responsible for coordinating voluntary movements. The first sign of ataxia is often a loss of balance, which progresses steadily towards incoordination affecting walking, posture, speech or eye movements, for example.
A distinction is made between ataxia of genetic origin, which affects both sides of the body and progresses slowly, and acquired ataxia, which occurs suddenly after a sudden brain injury. Acquired ataxia may be caused by a tumour, ruptured aneurysm or cerebral infection, but also by alcohol abuse or chemical intoxication. There are also congenital ataxias due to developmental malformations of the brain.
The causes and biological mechanisms of ataxia
Ataxias do not result from muscular weakness, but are caused by dysfunction of the central nervous system. Cerebellar ataxias occur when the cerebellum is affected; sensory ataxias are caused by damage to the spinal cord, and vestibular ataxias can also be distinguished. There are ataxias of genetic origin due to mutations in various genes (over 50 known to date) and acquired ataxias of sudden onset, caused by damage to the brain or spinal cord. To find out more about the causes of ataxia, visit our dedicated page.
Symptoms and diagnosis of ataxia
Cerebellar ataxias are characterised by a loss of coordination, with apraxia preventing patients from controlling the position of their limbs or their posture. Depending on the type of ataxia, dysmetria (loss of control over the amplitude of voluntary movements), dysarthria (loss of control over speech and its amplitude), nystagmus (loss of control over eye movements) and tremors may appear.
The diagnosis of ataxia is based on a clinical examination, brain imaging, electrophysiology tests and genetic analysis in family cases.
Treatments for ataxia
There is currently no approved treatment for cerebellar ataxia of genetic origin, for which physiotherapy, occupational therapy or speech therapy can relieve the symptoms.
Acquired ataxias can be treated according to their origin, whether toxic, traumatic or inflammatory. In the case of ataxia resulting from a brain tumour, for example, treatment with chemotherapy or surgery to eliminate the tumour will reduce or even eliminate the symptoms of ataxia.
