wllanos,
I am sorry to say it may not grow back. I am almost 5 years post op. I had the STA-MCA and EMS (indirect bypass -> muscle (and it's bloody supply) is laid down on the surface of the brain and left to grow). I have one larger bare patch behind my ear, and the thin line from my for head connectind the larger patch. I am a girl so i have benable to hide the patch and the lin with my hair. I would not worry about it. It gives me strength since i had open brain surgey and I am still alive to tell the tail!! I look at my scar as a opertunity to tell my story to other so they are more aware of MM. Since i am a girl I have an option to show it or not.  But i am only one of many, so maybe others have had more luck with regrowth.
I hope this helps!
Becky

wllanos,
I also had the indirect by-pass surgery like Becky. Mine was done almost six years ago. I have always worn my hair very short even before surgery. I have a thin scar line and a small patch by the ear like Becky. I am lucky to have a hairdresser who knows about my surgery and is able to cover my scar. Tell your brother to give it time and he may have to let his hair grow longer than he did before to cover the scar.
Sharon

Wherever there is scar tissue, the hair will not grow back, but all the surrounding hair should, just give it some time. Becky, I love your attitude! The scars on our heads are a badge of honor and triumph over something that can be really scary. They are also a great conversation starter!