Hi,
Thank you for posting your query.
Brain stem 
stroke is generally a serious issue and is associated with high morbidity (sickness) and mortality (death rate).
Regarding the swelling, it would be useful if you can upload the 
MRI brain reports.
As of now, supportive care and 
mechanical ventilation should be continued.
I hope my reply has helped you.
I would be pleased to answer, if you have any follow up queries or if you require any further information.     
Best wishes,
Dr Sudhir Kumar MD (Internal Medicine), DM (Neurology)
Senior Consultant Neurologist
Apollo Hospitals, Hyderabad,
For DIRECT QUERY to me:  http://bit.ly/Dr-Sudhir-kumar 
My blog: http://bestneurodoctor.blogspot.com/