Ataxia: classification

Ataxia: definition

From the Greek ataxiā (disorder, uncoordination), ataxia is the cardinal symptom of ataxic syndromes, characterized by the progressive and inevitable loss of muscular control, associated with a difficulty in performing voluntary movements: the ataxia expresses the final product of a series of genetic disorders or secondary lesions affecting the central nervous system. It should be remembered that, in ataxic syndromes, poor muscle coordination occurs in the absence of paralysis.

This article is dedicated to the classification of various forms of ataxia, while the next will be treated the triggering causes and the complete symptom picture.

Classification

There are many forms of ataxia, classified according to the affected anatomical region, the cause, age of onset and characteristics.

General classification of ataxia

First of all, it is necessary to draw a first general classification: the ataxia can affect both the trunk and the limbs, and the march. In the first case, limb ataxia is diagnosed by focusing only on the patient's posture, through the assessment of the individual limbs: in similar situations, the patient is not able to maintain an upright position despite maintaining a static position. The ataxic march, instead, appears only during the movement [taken from Netter's Neurology, by Karl E. Misulis, Thomas C. Head]

Another useful criterion for classifying the forms of ataxia is hyposthenia, as well as the reduction of muscle strength, a possible cause of ataxia: hypostenia, responsible for the lack of motor regulation, can only affect the proximal muscles or be con-cause of cerebellar ataxia and provoke, together with the loss of kinesthetic sensitivity (ability to control the movement of a body segment), walking deficits.

Anatomic classification of ataxia

Depending on the site affected, ataxias can be classified into four large groups:

Cerebellar ataxia : often associated with tumors, inflammatory and vascular lesions at the level of the cerebellum;
Cerebral ataxia : the cortex of the temporal, parietal or frontal site is involved;
Ataxiabirintica : the inner ear is affected;
Sensitive ataxia : the neoplasms associated with inflammatory processes characterize this ataxic form

Hereditary and secondary ataxias

Furthermore, ataxic syndromes can be hereditary or secondary, therefore a consequence of brain injury, such as trauma, viral infections, drug or alcohol abuse and repeated exposure to radiation.

Among the inherited ataxic forms we recall:

Friedreich's ataxia (very common), characterized by bone changes that mainly involve hands and feet, associated with progressive deterioration of the nervous system.
Spino-cerebellar ataxias (widespread forms): classified in turn in many other forms, depending on the triggering cause. Generally, the spino-cerebellar arteries are characterized by vertigo, tremor, lack of balance, areflexia (lack of reflexes).
Telangiectatic ataxia (Louis-Bar syndrome), characterized by immunodeficiency, eye and skin telangiectasia, and cerebellar ataxia
Cerebellar atrophy, neuro-vegetative pathology, usually generated by neoplasms, degenerative, toxic or vascular diseases
Charcot-Marie ataxia (or hereditary motor-sensory neuropathy) affects the peripheral nervous system
Sensitive ataxia (not to be confused with the cerebellar): due to lesions at the level of the dorsal columns or peripheral polyneuropathies [taken from Netter's Neurology, by Karl E. Misulis, Thomas C. Head]

Classification based on age of onset

Considering the age of onset of the disease, some types of ataxia are distinguished:

Actasia-teleagectasia and Hypoxic-ischemic syndrome (generally, occur within the child's two years of age)
Autosomal-dominant cerebellar ataxia, Friedreich's ataxia (between 2 and 5 years of age)
Spino-cerebellar ataxia, typical of adolescents

These ataxic syndromes are caused by a number of factors, such as: metabolic-type diseases, neuroblastoma, infections, poisoning, trauma, severe migraine, multiple sclerosis, Hodgkin's lymphoma and hereditary diseases.