**4. Essential evaluation and differential diagnosis**

The progression of ataxia from symptom onset to maximum deficit is to be known whether it is acquired, genetic or non-hereditary sporadic degenerative. Acquired ataxias usually present acutely and progress rapidly from vascular, immunemediated, infectious, and toxic causes. Substrate deficiencies (e.g., vitamin B1, B12, E, or A) and iatrogenic insults, other than acute drug overdose, present subacutely (**Table 1**) [27, 28].

A detailed history should be obtained to assist in identifying the cause of the ataxia. A detailed history and physical and neurological examinations should be performed. Neurological examination allows the clinician to identify the type of ataxia. Once the type of ataxia has been identified, other diagnostic tests should be performed according to the type of ataxia and the location of the lesion. Although most patients with ataxia have a primary neurological disease, it is important to know the cause can be metabolic disorders (e.g., hypoglycemia and hypocalcemia), toxins (e.g., lead and organophosphates), and medications (e.g., phenobarbital and metronidazole). Once a detailed history is obtained, physical and neurological examinations should be performed. The neurological examination can help clinicians to identify the type of ataxia. Once the type of ataxia is presumed, further diagnostic tests can be performed according to the type of ataxia and the lesion localization suspected [27].

Congenital diseases are also important causes of ataxia, specifically chronic ataxic syndromes such as Dandy–Walker Syndrome and Arnold Chiari Malformations. The Dandy–Walker syndrome is characterized by enlargement of the fourth ventricle in the posterior fossa, absence of the cerebellar vermis, and a cystic formation close to the internal base of the skull [28]. In Arnold Chiari malformations, the affected patient shows a downward displacement of the cerebellar tonsils through the foramen magnum with a presumed risk of complicating with a non-obstructive hydrocephalus [29].

Genetic ataxias can be highlighted as an autosomal dominant, autosomal recessive, or X-linked manner inheritance. The presence of a genetic disease does not exclude


### **Table 1.**

*Identifiable causes for non-hereditary ataxia.*

*Introductory Chapter: Insights into Ataxia DOI: http://dx.doi.org/10.5772/intechopen.113755*

the presence of an acquired etiology that may alter the presentation and course of ataxia symptoms and warrant further investigation. Likewise, the absence of a clear family history does not exclude the role of genetics within an apparently sporadic disorder. Often, the fact that family history has not been adequately obtained because the information is not straight available (adoption, loss of contact, non-cooperation, and paternity issues), due to non-dominant inheritance patterns (recessive, X-linked, and maternal/mitochondrial) or due to specific genetic processes that modify the presentation of the disease in the pedigree (anticipation, incomplete penetrance, and mosaicism) [24].

Adult-onset genetic ataxias may not appear to clinicians until later in the course of the disease due to their insidious onset and slow progression.

Progressive muscular atrophy appears much more quickly compared to tardive idiopathic ataxia and genetic ataxia, causing significant disability in a short space of time, with death occurring 6–10 years after the onset of symptoms. Genetic counseling and risk assessment depend on determining the specific cause of hereditary ataxia in an individual.
