This depends strongly on what kind of work they perform normally, as well as whether they have received treatment for the avm.
If avm is ruptured and actively bleeding, it's highly unlikely the person will be able to perform any kind of work.
Once treated, it's possible to slowly ease back into work, provided the work is easy and not very physical.
All brain trauma causes extreme fatigue, headaches, nausea, and a general feeling bad, so working can be tricky.