How is multiple system atrophy (MSA) diagnosed?

Updated: Sep 24, 2018
  • Author: Stephen M Bloomfield, MD; Chief Editor: Selim R Benbadis, MD  more...
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The Movement Disorders Society Scientific Issues Committee Report (MDSSICR) revised the diagnostic criteria for MSA in 2003. These criteria allowed for the classification of MSA by different levels of diagnostic certainty, such as possible, probable, and definite. [2] The report recommended that MSA be subdivided into 2 categories based on the neurosystem predominantly involved. Patients with predominant parkinsonian features are identified as having MSA-P, which replaces the term SND, whereas patients with prominent cerebellar dysfunction have MSA-C, which replaces the term OPCA. Patients with idiopathic PD are distinguished from patients with MSA by the lack of autonomic and cerebellar features, as well as by their response to carbidopa/levodopa. Autonomic dysfunction appears in all forms of MSA. Therefore, the term SDS is not useful. [3, 4]

MSA is most likely to be confused with idiopathic PD. In a prospective clinicopathologic study, the initial diagnosis of PD was correct in 65% of patients, a rate that improved to 76% with follow-up care. MSA was correctly diagnosed in 69% of patients who had been observed for at least 5 years. In MSA, autonomic insufficiency and cerebellar signs are the features most helpful with differential diagnosis. Distinguishing MSA from progressive supranuclear palsy (PSP) can be difficult; patients with the latter sometimes have cerebellar features and orthostatic hypotension. Some spinocerebellar ataxias (SCA) can manifest with clinical findings suggestive of MSA. SCA-3 and SCA-17 in particular can have these findings. [4]

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