It can mean a lot of different things as each and every brain injury is different. They vary in recovery times, amount of recovery and symptoms. Some common symptoms are memory loss, problems with complex speech, problems communicating, easily frustrated, loss of self esteem causing more frustration. Some have vision problems and coordination problems. It really depends on which part of the brain is injured and because he fell, it's probably a diffuse axonal injury, meaning axons are ripped and damaged throughout the brain and only time will tell. I advise you find a brain injury support group and meet people dealing with the same problems so you can best support your brother.

I'm sorry for your brother's struggles right now. Your and other emotional support is very important for him right now. Brain injuries are accumulative. In other words, a person gets trauma to the head neck or spine and recovers with no seemingly lasting affects. After a couple of more though, the person doesn't bounce back and maybe he can't balance his check book anymore, or planning is not good or short term memory is very bad. He seems to suffer more pain and has more digestive problems or doesn't sleep well at all.

What do you mean by recover. Will the person ever go back to exactly the way they were,like a cut healing? No. Can the person learn new strategies to cope and have a good life? To various degrees this may true depending on the challenges.

Cognitive means his ability to use his brain to problem solve and plan strategies. It may also include his ability to see patterns and respond appropriately in a "normal" time frame. It may also mean his ability to remember. It may also mean the ability to read body language and understand social conversation and/or directions while applying an appropriate work/physical response. It can also involve balance, eyesight, eye-brain coordination and many other related things.

I hope you seek out a good brain injury rehab doctor. A neuropsychologist may be of much more help to you than a neurologist. Be aware that medications have side affects and sometimes they are needed and sometimes other strategies are just as good without side affects. Research, ask lots of questions, keep notes on everything that is tried, names, medications, therapy names, and what the outcome is. Make sure humor and joy are constantly a part of the picture of your lives. The passion and love of doing things will help a person succeed much more than oughts or shoulds.

And it is important to honor the person for who they still are from their core, no matter how their brain works. Head injuries are very much like strokes in many ways. There is a good indie movie out called "Still Me" . Is is a short and may be of help.

My best to you and your brother.

Do not trust rehab all that much. They get paid to keep him unhealed. It all depends on the person. I have a brain injury, but I remember all my life, but I am "supposed" to have "memory problems." Whatever that means. Just test him daily to exercise the brain. Give him things to remember, then ask him later on for the stuff he still remembers, in any order. Either increase the list with time or test on "order" as an "advanced" quiz.
I am OutOfMind210:
http://forum.bodybuilding.com/showthread.php?p=493 113421#post493113421