Sorry to hear about your husband's declining health. If I'm totally honest I hadn't heard of Multiple System Atrophy until you mentioned it and I did some research on the NHS website. Symptoms appear to be almost identical to Parkinson's only, with PD medication can help to relieve the symptoms.
You may want to have a look here for more indepth information http://www.nhs.uk/conditions/multiple-system-atrophy/Pages/Introduction.aspx
Hopefully the original diagnosis stands least that though it cannot be cured, it can be treated.
Best wishes and please keep us up to date with his progress.
One day at a time is all I can say to you Philips one day at a time just live for that and try to stay happy , switch Off your thoughts as best you can and try to enjoy , your never going to make them all go away but try your best to , enjoy each day we all have to