Overview of Multisystem Atrophy
Multisystem atrophy (MSA) is a group of rare, multisystem degenerative diseases that have several clinical features of Parkinson's disease and are sometimes referred to as the "Parkinsonism-plus syndromes."
When MSA was first identified in 1960, it was named "Shy-Drager Syndrome" after the two physicians who first described its symptoms. Now, Shy-Drager Syndrome is recognized as one of three manifestations of multisystem atrophy. The other two are striatonigral degeneration and olivopontocerebellar atrophy (OPCA). The three are classified together because of their clinical overlap and neuroanatomical similiarities.
Multisystem atrophy has three cardinal features:
- Parkinsonism (see Parkinson's disease)
- Autonomic failure (including orthostatic hypotension, erectile dysfunction, and urinary incontinence or retention)
- Cerebellar ataxia (failure of muscular coordination)
All three characteristics occur in the majority of MSA cases, but with considerable variation with regards to specific attributes, and any one of the three may predominate. If autonomic failure predominates, MSA is known as Shy-Drager Syndrome. If parkinsonism predominates, it is known as striatonigral degeneration. Striatonigral degeneration is usually indistinguishable from Parkinson's disease, except that it does not respond to Parkinson's treatment. If cerebellar ataxia predominates, MSA is known as olivopontocerebellar atrophy (OPCA).
Although cognitive dysfunction may appear minimal, most patients do experience frontal system impairment and many develop dementia late in the course of the disease. MSA is generally more severe than Parkinson's. More than 40% of MSA patients are confined to a wheelchair or otherwise severely disabled within 5 years of initial diagnosis. Except in a few cases, the drug of choice for Parkinson's patients (levedopa) has no effect on MSA and may even worsen symptoms.
Incidence and Prevalence of Multisystem Atrophy
MSA affects men twice as often as women. The average age of onset is 50 years old, and the average survival time after initial diagnosis is 10 years. As many as 10% of Parkinson's cases that are diagnosed incorrectly are identified as MSA upon autopsy.