Ataxia: causes, symptoms and treatments
We discover a clinical sign that causes the inability to coordinate body movements.
Ataxia is a Greek term meaning "disorder". We refer to ataxia as a clinical sign characterized by the incoordination of movementAtaxia is characterized by: lack of stability in gait; clumsiness or weakness in the upper and lower limbs, body or eye movements, etc. as a consequence of an involvement of the central nervous system (CNS).
In general terms, ataxia is usually secondary to an involvement of the cerebellum or its efferent or afferent nerve pathways, although other brain structures may cause this symptomatology. In this article we will review the characteristics of this phenomenon.
Symptoms of ataxia
Although the main features of ataxia are uncoordinated limb and saccadic eye movements, other types of symptoms may occur. All of 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.
Difficulties in visuospatial perception due to oculomotor incoordination.
Visuoconstructive apraxia as a consequence of incoordination.
Dysphagia -swallowing problems-.
Difficulties in walking, with a tendency to open the legs.
Total loss of the capacity to walk.
As we have said, in the clinic ataxia usually appears as a sign that can manifest itself in different acquired pathologies. -i.e.: cerebral infarcts, tumors, craniocerebral trauma, etc.- although it can also present as an isolated disease in its hereditary forms.
Classifications (types of ataxias)
Ataxia could be classified according to different criteria, although in this review we will explain the main types of ataxia. we will explain the main types of ataxia depending on whether the pathology has been acquired or is hereditary.. Another possible way of classification would be according to the regions of the Central Nervous System that present lesions or anomalies susceptible to produce ataxia.
1. Acquired ataxias
Acquired ataxia implies that it is produced as a consequence of a main pathology suffered by the patient. Thus, cerebral infarcts, 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.thalamus or dorsal root ganglia. A very frequent cause of ataxia is cerebellar hemorrhage.
The anamnesis, the study of the case and the appropriate selection of diagnostic tests are necessary to find the correct etiology. Treatment will be focused on the intervention of the acquired pathology and the prognosis will depend on the severity of the lesions.
2. Recessive hereditary ataxias
Unlike acquired ataxias, these types of ataxia usually have an early onset, during childhood or between 20 and 30 years of age. That the disease is recessive implies that we must have inherited two equal copies of the "defective" gene from our parents.
This implies that many people are simply carriers of the disease even if it does not manifest itself, since one "healthy" gene is enough to avoid developing 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. Its prevalence in developed countries is estimated to be 1 person per 50,000 cases. Its onset is usually in childhood, presenting gait problems, clumsiness, sensory neuropathy and eye movement abnormalities. Other less frequent consequences may include skeletal deformities and hypertrophic cardiomyopathy.
As the disease progresses, dysarthria - alteration in the articulation of words - dysphagia - difficulty in swallowing -, weakness in the lower extremities, etc. are more apparent. It is estimated that between 9 and 15 years after the onset of symptoms, the person loses the ability to walk.
This clinical picture is a consequence of neurodegeneration of dorsal root ganglion cells, spinocerebellar tracts, cells of the dentate nucleus -a deep nucleus of the cerebellum- and corticospinal tracts. Purkinge cells - the main cells of the cerebellum - are not affected. Neuroimaging usually does not show any apparent involvement of the cerebellum.
There is currently no cure and the treatments administered are usually symptomatic.. The risk due to dysphagia, cardiomyopathy, etc., means that patients should be followed regularly. Several clinical trials are underway to observe the potential of various drugs such as, among others, interferon-gamma.
With an estimated prevalence of 1 case in 20,000-100,000 cases, ataxia-telangiectasia (AT) is the most common cause of recessive ataxia in patients under 5 years of age. As the disease develops we can find hypotonia -decreased Muscle tone-, polyneuropathy -affection of the peripheral nervous system-, oculomotor apraxia -problems in shifting the gaze towards a stimulus that must be fixed-, etc. Patients with TA usually present immunodeficiencies that cause recurrent pulmonary infections.
In the neuroimaging study, atrophy of the cerebellum can be observed, unlike in Friederich's ataxia.. As in the previous case, treatment is directed at the symptoms and there is no cure.
2.3. Other recessive hereditary ataxias
We find many more types of hereditary ataxias such as Ataxia with oculomotor apraxia, Cayman Ataxia, Ataxia with vitamin E deficiency, infantile spinocerebral Ataxia, etc.
3. Dominant hereditary ataxias
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 they 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 thing.
From a neuropsychological point of view, the main differential diagnosis to be made is to distinguish ataxia from apraxia.. Although they may involve similar cognitive deficits, especially in the acquired forms, they are significantly different from a clinical point of view. Apraxia is defined as a disturbance in the execution of certain learned movements in response to a command and out of context that is not attributable to sensory or motor impairments, lack of coordination or attentional deficits.
Ataxia, on the other hand, is a motor coordination deficit as such. Although a patient may not be able to execute the required action on command, it will be due to motor inability. In apraxia the problem arises because the "verbal input" -i.e., the command- cannot be associated with the motor response or "motor output".
On the other hand**, in apraxia we should not encounter other problems such as gait instability**, swallowing problems, etc. Thus, in these cases, neurological evaluation will be mandatory if we observe signs incompatible with apraxia. However, it should also be noted that both clinical manifestations may occur concomitantly.
The incidence of ataxia at the national level
With the prevalences we have mentioned in the case of ataxia in its hereditary form, we can consider these diseases as rare -a rare disease in Europe being one case in every 2000 persons-. When diseases are classified as rare, it is generally more difficult to advance in their research to find effective treatments. to find effective treatments.
In addition, as we have seen, the hereditary forms of the disease mostly affect 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. These include the Catalan Association of Hereditary Ataxias, the Sevillian Association of Ataxias and the Madrid Association of Ataxias.
Ataxia, although not very prevalent in its hereditary manifestation, is a disorder that affects the activities of daily living and independence in the lives of many people, especially in the young population.especially in the young population. In addition, pharmaceutical and business priorities mean that research in this field is progressing slowly, so that treatment proposals are focused on palliative care.
That is why its existence must be publicized and its affectations made known. Each step, however small, can represent improvements in the quality of life of these patients, with the relief for the healthcare system that this entails. The study and development of early detection and automation of treatment systems will benefit patients, families, caregivers and healthcare professionals alike. When we advance in these fields, everyone wins and, for this reason, we must publicize and support these social causes.
(Updated at Mar 28 / 2023)