Multiple system atrophy

Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by tremors, slow movement, muscle rigidity, postural instability (collectively known as parkinsonism), autonomic dysfunction and ataxia. This is caused by progressive degeneration of neurons in several parts of the brain including the basal ganglia, inferior olivary nucleus, and cerebellum. MSA was first described in 1960 by Milton Shy and Glen Drager and is also known as Shy–Drager syndrome.

Many people affected by MSA experience dysfunction of the autonomic nervous system, which commonly manifests as orthostatic hypotension, impotence, loss of sweating, dry mouth, urinary retention and incontinence. Palsy of the vocal cords is an important and sometimes initial clinical manifestation of the disorder.

A prion of the alpha-synuclein protein within affected neurons may cause MSA. About 55% of MSA cases occur in men, with those affected first showing symptoms at the age of 50–60 years. MSA often presents with some of the same symptoms as Parkinson's disease. However, those with MSA generally show little response to the dopamine agonists used to treat Parkinson's disease and only about 9% of MSA patients with tremor exhibit a true parkinsonian pill-rolling tremor (an involuntary, rhythmic movement of the thumb and index finger suggesting the rolling of a pill between them).

MSA is distinct from multisystem proteinopathy, a more common muscle-wasting syndrome. MSA is also different from multiple organ dysfunction syndrome, sometimes referred to as multiple organ failure, and from multiple organ system failures, an often-fatal complication of septic shock and other severe illnesses or injuries.