I have a concussion and smoke 2 cigs a day? i know nicotine decreases blood flow, will this cause permanent damage?

Concussion: It is likely there will be no long term effects from your concussion, but an exam and possible CT of the brain would be in order, if not already done. The nicotine does not play in here, directly.

Yes but not that way: Smoking damages many body parts, &may be permanent. Smoking causes cell mutation in respiratory tract, which can be permanent &eventually lead to cancer. Smoking also damages circulatory system so eventually can cause stroke &heart attack, which again causes permanent damage. Smoking also damages lung tissue which leads to emphysema, also permanent. But won't affect a concussion.