Welcome to NT. Regarding your question on the measurement, attached are the verbatim comments from the neuropsychologist that conducted my NPA (this following a TBI categorized as severe):

“On examination, the patient demonstrated intact cognition in all domains assessed including learning and memory, attention, processing speed, language skills and executive functions. He has shown an excellent recovery from his severe injury only five months age. From a cognitive standpoint there are no concerns with respect to the patient returning to work full time or returning to driving.”

I personally have spoken to several people who have had concussions and are symptom free. That said most studies suggest that once a person sustains a concussion or other type of TBI, they are more susceptible to long term problems if they suffer additional head injury.

I hope this helps assuage some of your fears.

Some links that may be useful:

http://www.cdc.gov/concussion/feel_better.html

http://www.webmd.com/brain/post-concussion-syndrome

Best to you in your recovery.