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Multiple System Atrophy

Clinical Features, Ataxia, Autonomic Dysfunction, TreatmentCognitive function, Natural history

Multiple system atrophy is a group of disorders that share common clinical features, which include Parkinsonism, problems with balance (ataxia), and dysfunction of the autonomic nervous system. It is a sporadic neurodegenerative disease of adult onset. Its cause remains unknown.

Parkinsonism is a part of the constellation of symptoms, hence multiple system atrophy also falls within the rubric of disorders called Parkinson-plus syndromes. In addition to multiple system atrophy, Parkinson-plus syndromes include progressive supranuclear palsy and corticobasal ganglionic degeneration. Some also consider Lewy-body disease to be one these syndromes. The Parkinson-plus syndromes are distinct from idiopathic Parkinson's disease because of certain aspects of clinical presentations, but more importantly, are differentiated by clinical response to treatment with L-dopa and related drugs, and neuropathology. In early stages, Parkinson-plus syndromes can be difficult to distinguish from idiopathic Parkinson's disease. However, patients with idiopathic Parkinson's disease have significant improvement of symptoms with dopaminergic drugs, while patients with Parkinson-plus syndrome have, at best, a modest response, so that a diagnosis of Parkinson-plus syndrome is often first considered only when patients show an atypically modest response to treatment. Within the context of Parkinson-plus syndromes, multiple system atrophy is a distinct entity because of its clinical features and neuropathological expression.

In 1900, Déjérine and Thomas coined the term olivopontocerebellar atrophy to describe a disorder in which the predominant clinical feature was ataxia, but also included parkinsonism and autonomic dysfunction. In 1960, Shy and Drager described patients in whom there was predominant autonomic dysfunction manifested primarily by a sudden fall in the blood pressure on standing (orthostatic hypotension). These patients also had parkinsonism, and to a lesser degree, ataxia. The disorder has been called Shy-Drager Syndrome. In the 1960s, Adams and his colleagues described a group of patients with predominant parkinsonism who also had autonomic failure and, to a lesser degree, ataxia. They termed this disorder striatonigral degeneration.

The neuropathological description of these disorders shows changes in various structures, predominantly the basal ganglia, cerebellum, and certain brainstem nuclei. Because of the common features, both clinically and neuropathologically, Graham and Oppenheimer suggested that these three sporadic, adult-onset, neurodegenerative disorders be considered as one diagnostic entity, namely multiple system atrophy. This grouping of patients with sporadic olivopontocerebellar atrophy, striatonigral degeneration, and Shy-Drager Syndrome as one entity was further strengthened by the observation that all these disorders had a common neuropathological feature, namely intracytoplasmic inclusion bodies (a collection of abnormal molecules) in the oligodendrocytes, which are cells that provide structural and functional support for the brain cells (neurons).

The majority of patients with multiple system atrophy displays a mild form of cognitive impairment reflecting frontal-subcortical system dysfunction. This is predominantly manifested by disturbances in attention, mild problems with memory, visuospatial dysfunction, and executive dysfunction.

The age range for onset of multiple system atrophy is between 33.3 years to 75.6 years with a mean age of onset of this disease at 52.5 years. The male to female ratio ranges from 1.1:1 to 1.9:1. Mean survival time ranges from 5.5 to 9.5 years.

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