Multiple System Atrophy

Diagnosis

The diagnosis of MSA is a clinical one. Consensus criteria have been developed under the co-sponsorship of the American Autonomic Society and the American Academy of Neurology.

Symptoms are grouped into clinical domains, and the diagnosis is defined as "possible" or "probable" based on the number of criteria met and features present within each domain. The involvement of each domain as part of the MSA diagnosis is as follows:

Autonomic and urinary dysfunction domain
Diagnostic criteria:

• Orthostatic fall in BP by > 30 mm Hg systolic or 15 mmHg diastolic; OR
• Urinary incontinence (persistent involuntary partial or total bladder emptying, accompanied by erectile dysfunction in men); OR
• Both

Parkinsonism domain
Diagnostic criteria:

• Bradykinesia, plus at least one of rigidity, postural instability, or tremor

Cerebellar dysfunction domain
Diagnostic criteria:

• Gait ataxia, plus at least one of ataxic dysarthria, limb ataxia, or sustained gaze-evoked nystagmus

Possible MSA: One criterion (i.e., autonomic, parkinsonism, or cerebellar dysfunction), plus features from the two other domains. Poor levodopa response is considered a feature of parkinsonism in this context.

Probable MSA: Autonomic criteria, plus parkinsonism with poor levodopa response or cerebellar dysfunction.

Exclusion criteria: onset < 30 years of age, family history, non-medication related hallucinations, and dementia.

Other clues to the presence of MSA include orofacial dystonia and REM sleep behavior disorder. Definitive diagnosis occurs only at autopsy.