Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying disfunction of the parts of the nervous system that coordinate movement, such as the cerebellum.
Several possible causes exist for these patterns of neurological dysfunction.
The International Ataxia Awareness Day is observed on September 25 each year.
The term "ataxia" is sometimes used in a broader sense to indicate lack of coordination in some physiological process.
Examples include optic ataxia (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects.
Optic ataxia may be caused by lesions to the posterior parietal cortex. The posterior parietal cortex is responsible for combining and expressing positional information and relating it to movement.
Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention.
Optic ataxia is usually part of Balint's syndrome, but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between visual-association cortex and the frontal premotor and motor cortex), and ataxic respiration (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the medulla oblongata).
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