Definition of Multiple system atrophy:

Multiple system atrophy (MSA) is a rare degenerative condition that causes symptoms similar to Parkinson's disease. However, patients with MSA have more widespread damage to the autonomic nervous system, the part of the nervous system that controls involuntary functions.

Causes, incidence, and risk factors:

MSA is characterized by the following:

• Progressive damage to the nervous system, leading to low blood pressure when standing, difficulty urinating, and abnormal breathing during sleep
• Muscle tremor and rigidity
• Slow movement
• Disrupted REM sleep patterns

The cause is unknown. MSA develops gradually and is most often diagnosed in men older than 60.