have people seen this? if so, why isn't this the standard rec after a concussion?

http://www.ncbi.nlm.nih.gov/pubmed/23372680

There have been numerous studies that have shown specific substances to be beneficial after concussion, but, like this one, they all require administering the substance within a short window after the concussion. For those concussions that result in an ER visit, NAC would be worthwhile. But, getting doctors to follow this protocol would be difficult.

Many concussions that include an ER visit are overlooked because there are other injuries that stand out. Concussion specialists have acknowledged this situation and have recommended that complete trauma history be take, yet, it rarely is. When concussion symptoms persist or even manifest for the first time days later, there protocols are no longer effective.

It sounds like these and other protocols are most valuable in preventing the escalation of concussion symptoms. If the ER presentation is of what appears to be a very mild concussion, getting the doctor and/or patient to follow the protocol would be unlikely.

Welcome to the convoluted thought process of doctors as they see concussion patients.