Ataxia: causes, symptoms and treatments
Ataxia It is a Greek term meaning "disorder". We refer to the ataxia as a clinical sign characterized by the lack of coordination of movement: lack of stability in walking; clumsiness or weakness in the upper, lower extremities, body or eye movements, etc. as a consequence of an affectation of the Central Nervous System (CNS).
In general, ataxia is usually secondary to involvement of the cerebellum or its efferent or afferent nerve pathways, although other brain structures could cause this symptomatology. In this article we will review the characteristics of this phenomenon.
Symptoms of ataxia
Although the main characteristics of ataxia are the uncoordination of the extremities and the saccades of the eyes, other types of symptoms can occur. All the symptoms of ataxia, however, have to do with the ability to move parts of the body. These signs that ataxia is affecting normal body functions are described below.
- Speech problems
- Difficulties in visuospatial perception due to oculomotor uncoordination.
- Visuoconstructive apraxia as a consequence of the lack of coordination.
- Dysphagia-problems to swallow.
- Difficulties in walking, with a tendency to open the legs.
- Total loss of the ability to walk.
As we said, in the clinic, Ataxia usually appears as a sign that can manifest itself in different pathologies acquired - that is to say: cerebral infarcts, tumors, cranio-encephalic traumatisms, etc. - although it can also present itself as an isolated disease in its hereditary forms.
Classifications (types of ataxias)
We could classify ataxia according to different criteria, although in this review We will explain the main types of ataxia depending on whether the pathology has been acquired or is hereditary . Another possible classification mode would be based on the regions of the Central Nervous System that present lesions or anomalies capable of producing ataxia.
1. Acquired ataxias
That an ataxia is acquired implies that it occurs as a consequence of a major pathology suffered by the patient. In this way, cerebral infarctions, cerebral anoxia - lack of oxygen in the brain - brain tumors, trauma, demyelinating disease - multiple sclerosis - are common causes of ataxia.
Among other less common causes we could find congenital anomalies, infections, other autoimmune diseases, Human Immunodeficiency Virus, Creutzfeldt-Jakob disease, etc. In general terms, For ataxia to occur, these pathologies must cause damage to the cerebellum or related structures such as the spinal cord. , thalamus or ganglia of the dorsal root. A very frequent cause of ataxia is cerebellar hemorrhage.
The anamnesis, the case study and the appropriate selection of diagnostic tests are necessary to find the correct etiology. The treatment will be focused on the intervention of the acquired pathology and the prognosis will depend on the severity of the injuries.
2. Recessive hereditary ataxias
Unlike acquired ataxias, these types of ataxia are usually early onset, during childhood or between 20 and 30 years. That the disease is recessive implies that we must have inherited two equal copies of the "defective" gene from our parents.
This implies that a large population is simply carriers of the disease even if it does not manifest itself, since with a "healthy" gene it is enough not to develop it. In this group we find some of the most common types of ataxia such as Friederich's Ataxia or Ataxia-Telangiectasia.
2.1. Friederich's ataxia
It is the most common type of hereditary ataxia. It is estimated that its prevalence in developed countries is 1 person for every 50,000 cases. Its onset is usually in childhood, presenting gait problems, awkwardness, sensory neuropathy and abnormalities in the movement of the eyes. Other less frequent consequences may be skeletal deformities and hypertrophic myocardipathies.
As the disease progresses, dysarthria - alteration in the articulation of the words -, dysphagia - difficulty in swallowing, weakness in the lower extremities, etc. they are more apparent It is estimated that between 9 and 15 years of the onset of symptoms the person loses the ability to walk.
This clinical picture is a consequence of the neurodegeneration of the ganglion cells of the dorsal root, the spinocerebellar tracts, the cells of the dentate nucleus -a deep nucleus of the cerebellum- and the corticospinal tracts. The Purkinge cells - the main cells of the cerebellum - are not affected.The neuroimaging study does not usually show any apparent involvement of the cerebellum.
Currently there is no cure and the treatments administered are usually symptomatic . The risk due to dysphagia, cardiomyopathy, etc., implies that patients should be followed regularly. Several clinical trials are under way to observe the potential of various drugs such as, inter alia, interferon-gamma.
With an estimated prevalence of 1 case between 20,000-100,000 cases, ataxia-telangectasia (AT) is the most common cause of recessive ataxia in patients younger than 5 years. As the disease develops we can find hypotonia - decreased muscle tone - polyneuropathy - involvement of the peripheral nervous system - oculomotor apraxia - problems in changing the look towards a stimulus to be fixed -, etc. Patients with AT usually have immunodeficiencies that cause recurrent lung infections.
In the neuroimaging study, atrophy of the cerebellum can be observed, unlike Friederich's ataxia . As in the previous case, the treatment is directed to the symptoms and there is no cure.
2.3. Other hereditary recessive ataxias
We found many more types of hereditary ataxias such as Ataxia with oculomotor apraxia, Ataxia Cayman, Ataxia with vitamin E deficiency, infantile spinocerebral ataxia, etc.
3. Dominant hereditary ataxia
The dominant hereditary ataxias occur in each generation of a family with a 50% risk of receiving the disease from one of the parents . In this case, a single copy of the affected gene is sufficient to develop the disease. Depending on the course of the disease can be divided into episodic or progressive. There are different genetic tests for the diagnosis of these pathologies. As in the previous cases, there are no cures either.
Ataxia and apraxia: they are not the same
From a neuropsychological point of view, the biggest differential diagnosis that must be made is to distinguish ataxia from apraxia . Although they can lead to similar cognitive deficits, especially in the acquired forms, they are significantly different from a clinical point of view. Apraxia is defined as an alteration in the execution of certain movements learned in response to an order and outside the context that is not attributable to sensory or motor impairments, lack of coordination or attentional deficits.
Ataxia, on the other hand, is a coordination motor deficit as such. Although a patient can not perform the required action before an order, it will be due to motor disability. In apraxia the problem arises because the "verbal input" - that is, the order - can not be associated with the motor response or "motor output".
On the other hand, in apraxia we should not find other problems such as the instability of walking , problems in swallowing, etc. Thus, in these cases the neurological evaluation will be mandatory if we observe signs incompatible with apraxia. However, it should also be taken into account that both clinical manifestations can be presented concomitantly.
The incidence of ataxia nationwide
With the prevalences that we have cited in the case of ataxia in its hereditary form, we can consider these diseases as rare - being in Europe a rare disease that is one case every 2000 people-. When diseases are classified as rare, it is generally more difficult to advance their research to find effective treatments.
In addition, as we have seen, the hereditary forms of the disease will affect mainly children and young people. This has led to the emergence of various non-profit associations that promote the treatment, dissemination and improvement of the quality of life of these patients. Among them we find the Catalan Association of Hereditary Ataxias, the Sevillian Association of Ataxias and the Madrilenian Association of Ataxias.
Ataxia, although not very prevalent in its hereditary manifestation, is a disorder that affects the activities of daily life and independence in the lives of many people , especially in young population. In addition, pharmaceutical and business priorities mean that research in this field advances slowly, which is why the proposals regarding treatment focus on palliative care.
That is why you should disclose their existence and let know their affectations. Each step, however small, may represent improvements in the quality of life of these patients, with the relief for the health system that this entails. The study and development in early detection and the automation of treatment systems will be beneficial for patients, family members, caregivers and health professionals. When we advance in these fields, we all win and, for this reason, we must make known and support these social causes.
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