Ataxia is defined as an inability to coordinate movements. Ataxia produces, for example, balance problems, gait and speech disturbances as well as jerky movements. The underlying pathology is often a dysfunction of the cerebellum and its connecting pathways, but ataxia may also be associated with a dysfunction of the posterior funiculus of the spinal cord or the sensory peripheral nervous system (sensory ataxia). Ataxia may be a symptom of a variety of neurological disorders. In these cases the clinical picture will usually also include other neurological abnormalities. However, the most usual cause of ataxia is prolonged abuse of alcohol. True ataxia is caused by the degeneration of the cerebellum or its connecting pathways of either hereditary or unknown (idiopathic) aetiology.