Ataxia refers to a disorder of balance and coordination of movements, of neurological origin. It is a symptom and not a disease, which can have several causes. How to recognize it? Explanation by neurologist Olivier Rouaud.
Ataxia is not a pathology, but a symptom : “It’s a type of balance or motor coordination disorder. This symptom is the result of dysfunction of certain structures of the nervous system such as the cerebellum, the vestibular system or the sensory system”, explains Olivier Rouaud, neurologist. ataxia not about musclesso muscle strength is retained. We also talk about “tendon dance” to designate this clinical sign. It is defined by an abnormally significant contraction of the tendons of the foot and ankle muscles (tibialis anterior, extensor digitorum longus, extensor hallucis longus). These disorders can appear when standing, walking or performing a movement. The cause can have several origins: dysfunction of the cerebellum, vestibular damage… We therefore distinguish three types of ataxia: proprioceptive ataxia, cerebellar ataxia and vestibular ataxia.
Proprioceptive ataxia
Proprioceptive ataxia is due to damage to the peripheral or central proprioceptive pathways, which causes a deficit in deep sensitivity. “In this case, in addition to the classic symptoms, the person has a balance disorder which is accentuated if he no longer has visual cues (walking in the dark or with his eyes closed causes imbalance and falls) “, explains the doctor.
Cerebellar ataxia
Cerebellar ataxia is caused by dysfunction of the cerebellum. In this case, it is the ability to coordinate and execute the movement that is affected: “It is distinguished from the others, because the individual will have a so-called “impaired” walk as under the effect of alcohol”, he explains. This type of ataxia can occur after a stroke of the cerebellum.
Vestibular ataxia
In the case of vestibular ataxia, the symptom is caused by a problem with the inner ear: “ There will be a feeling of instability, a bit like when you have fun spinning around very quickly with your eyes closed, then you stop and open your eyes, there is a tendency to the side and we fall”, details the neurologist.
Friedreich’s Ataxia
Friedreich’s disease (for the name of the neurologist who found it) or Friedreich’s ataxia is a genetic and progressive disease. It is therefore not only ataxia, but a real disease with associated symptoms. In addition to disorders of balance and coordination of movements due to ataxia, there is cardiac involvement, osteo-articular disorders and sometimes diabetes.
Ataxia is manifested by a disturbance of walking and balance. There may thus be frequent falls and imprecise movements. “When this symptom integrates a procession of other signs, we move towards a syndrome qualified as cerebellar or vestibular or even sensory proprioceptive”, says the doctor. In children, certain infections due to a virus, such as chickenpox, can cause so-called “acute” ataxias. They disappear spontaneously in a few days.
There are many possible causes of ataxia:
→ stroke (stroke) or a transient ischemic attack (TIA or mini-stroke), that is to say the temporary obstruction of a cerebral artery which resolves naturally, without leaving any sequelae. “Cerebellar stroke can cause acute cerebellar-like balance disorder,” explains the doctor.
→ It can also come from a head trauma, cerebral palsy, damage caused to the brain during birth, but also neurological complications of the varicella virus in the form of cerebellitis or a tumor, cancerous or benign, which affects the cerebellum.
→ You should also know thata small stone (lithiasis) in the inner ear, called benign paroxysmal vertigocan cause vestibular-type ataxia.
→ “There are also progressive forms of these symptoms, adds neurologist Olivier Rouaud. For example, some toxins like chronically consumed alcohol alter the proprioceptive nerve fibers and the cerebellum causing irreversible gait and balance disorders.”
→ Finally, ataxia can be caused by diseases of genetic origin which can alter these organs of balance, such as Friedreich’s ataxia or the various forms of spinocerebellar ataxia.
Ataxia can develop from birth, in the event of a genetic disease for example, or at any age of life.
The clinical examination of the doctor or the neurologist will be able to specify the semiology. “Depending on the context of occurrence, the mode of installation, the evolution, this will make it possible to find a cause and we will do certain examinations to confirm it”, explains the doctor. Among these examinations, we go from blood test at theBrain MRI and the cerebellum most often, sometimes going through an ENT check-up and sometimes Electro-Neuro-Myogram or a spinal cord MRI, to assess proprioceptive sensory pathways.
The treatment of the symptom of ataxia depends on the treatment of its cause, and there are many of them. “Following this, it is possible to also offer physiotherapy, sometimes vestibular”, explains the neurologist.
→ If the cause is a stroke and that it is taken care of very quickly, it is possible not to have any sequelae, hence the importance of calling the SAMU in the slightest doubt.
→ In the case of genetic or degenerative diseases with progressive alteration of the cerebellum, there is currently no curative treatment. But “certain drugs have a metabolic effect in Friedreich’s ataxia to help the cells to remain oxygenated in order to progress more slowly, which must be combined with physiotherapy when walking is impaired or speech therapy when speech is touched”. There are also encouraging prospects with gene therapy or MIN-102, but this possibility is still at the research stage.