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The development of ataxia is a neurologic sign that
may provide a clue to the nature of the underlying disorder. Interruption of
afferent and efferent connections within the spinocerebellar system results
in ataxic gait, scanning dysarthria, explosive speech, intention tremor,
dysdiadochokinesia, dysmetria, and abnormalities of eye movements. Many
variations are encountered in the clinical phenotype, ranging from findings
of pure cerebellar dysfunction to mixed patterns of involvement reflecting
extrapyramidal, brainstem, and cerebral cortical involvement.
Spinocerebellar Ataxia represents a group of hereditary ataxia of varying
inherited degrees of rarity, which is in contrast to a related group of
neurological disorders that are acquired following traumatic injuries or
other external agents. Until recently, all autosomal dominant ataxias were
called Marie Ataxia and all autosomal recessive ataxias were called
Friedreich Ataxia. They may be present at almost any time between infancy
and adulthood. (Table S-2)
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