Hello dear
Warm  welcome to Healthcaremagic.com
I have evaluated your query in details  .
*  Treatment  depends upon the time of diagnosis largely
@  Within 6 - 8 hours of onset and diagnosis with
     -  
MRI  with DWI  imaging      
     -  Intravenous  or Intra  arterial  
thrombolysis  with  mechanical  
        endovascular  therapies  
     -  treatment  of  vascular  risk  factors  , statins , anti platelets , other
         supportive  care .
*  Prevention  is  mainly  managing avoidance of recurrence  with  proper
    medical  management  with  statins  and  anti platelets .
*  Prognosis  is  dependent  upon multiple  factors  -  extent of vascular
    involvement  -  type of therapy  -  response  of  the  patient  -  medical
    management  -  other  co morbid  conditions  underlying .
Hope this  will help you for sure   .
Wishing  him  fine recovery .
Welcome for any further  guidance .
Regards  .