Multiple System Atrophy is a serious degenerative neurological disease that affects multiple body systems and quickly robs its victims of the ability to walk, talk, chew, swallow and breathe. There are various symptoms that fall into three general categories: autonomic dysfunction, cerebellar dysfunction and parkinsons-like symptoms. These symptoms can occur in any combination.
You can think of MSA like the three flavored Neapolitan ice cream. Everyone with MSA gets a scoop of the MSA ice cream just as everyone at a birthday party gets a scoop of Neopolitan ice cream in their dish. If you were at the party and looked at your dish and at the dish of the person next to you, you would notice that there is not the exact same amount of vanilla, chocolate and strawberry in both of the dishes.
In someone with Multiple System Atrophy, if their early symptoms are mainly CEREBELLAR like ataxia (loss of balance), slurred speech or difficulty swallowing they have mostly vanilla ice cream in their dish.
If their symptoms are mainly PARKINSONISM like tremors and slowness of movement they have mostly chocolate ice cream in their dish.
If their symptoms are mainly AUTONOMIC like neurogenic orthostatic hypotension or urinary incontinence, urinary retention or sexual dysfunction they have mostly strawberry ice cream in their dish.
Everyone needs to have some strawberry symptoms to have possible MSA.
On top of this they need to have some vanilla and some chocolate symptoms too.
Note that they may have a whole lot of vanilla and a tiny bit of chocolate. If so they are called MSA-C (cerebellar).
If they have a whole lot of chocolate and a tiny bit of vanilla they are called MSA-P (parkinsonism).
People with MSA have a changing bowl of ice cream though, their vanilla and chocolate and strawberry amounts increase over time as they develop more symptoms from the cerebellar or the parkinsons or the autonomic sides but this will vary from person to person. This is because the disease is spreading throughout the brain and is affecting different brain regions. It does not spread exactly the same way in every person.