Ataxia literally means lack of order and is used in clinical neurology to denote the symptom of incoordination. Ataxia is also used to denote a group of progressive neurodegenerative disorders in which ataxia as the prominent clinical manifestation. Most of the ataxia disorders are due to degeneration of the cerebellum and its afferent and efferent connections.

Current classifications distinguish between hereditary and non-hereditary ataxias. The hereditary ataxias are further divided into the autosomal recessive ataxias, the most frequent of which is Friedrich ataxia (FRDA), and the autosomal dominant spinocerebellar ataxias (SCA). Recently, the causative mutations of many hereditary ataxias have been identified.

The non-hereditary ataxias are separated into the acquired ataxias, such as alcoholic cerebellar degeneration (ACD) or paraneoplastic cerebellar degeneration (PCD), which are due to known exogenous or endogenous causes, and the sporadic degenerative ataxias, such as multiple system atrophy (MSA) or sporadic adult onset ataxia (SAOA).

Treatment of ataxias remains a challenge. Although not shown in formal trials, it is assumed that physiotherapy and speech therapy are helpful in ataxia. The goal should be to maintain the highest possible level of autonomy, to cope with physical disability and to prevent secondary complications. With progression of the disease many patients will require walking aids and a wheelchair. To date, there is no medication that improves the symptom of ataxia. Therapies based on the knowledge of the underlying molecular pathogenesis are available only for a limited number of quite rare ataxia disorders, such as ataxia with isolated vitamin E deficiency (AVED) or cerebrotendinous xanthomatosis (CTX). There are no treatments for the more prevalent ataxias, such as FRDA or the SCAs. However, a number of promising clinical trials in FRDA are underway, and clinical trials in SCAs are in preparation.