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.