What is post-concussion syndrome?

Post-concussion syndrome, or postconcussive syndrome as it is sometimes referred to ("PCS"), is a diagnostic label applied to a set of symptoms that sometimes arise following a concussion.  These symptoms may last days, weeks or months, but a diagnosis of PCS is usually not made until several months following an injury.  The symptoms are the same as those for a mild traumatic brain injury ("TBI").  They include headache, difficulty concentrating, irritability, and emotional and behavioral changes.