Post-Concussion Syndrome is worth mentioning because in my experience it is most often the result of poor communication and error in diagnosis, and therefore of iatrogenic (physician generated) origin. Anatomically, the cerebrum is the brain, and a true cerebral concussion is a temporary physiological (not neurological and no MRI abnormality) dysfunction of the brain, followed by full recovery (as occurs when the leg “falls asleep” during a movie). It includes being unconscious and losing short term memory of the accident. This differs from a cerebral contusion which causes clear injury to the brain, with neurological and MRI changes, and may have long term consequences.
Pliny the Elder said “He who saw the lightning and heard the thunder is not the one who was struck.” So when a patient who had a blow to the scalp (remember the brain is protected by a bony skull) tells me all the details of the accident, I know he wasn’t brain injured even if he believes he was momentarily unconscious. The correct diagnosis is a scalp contusion, and that’s like a contusion to the arm, leg, or any other part of the body that happens in any football game. The scalp is sore for a while, and gets well.
The word “concussion” has meaning to lay persons very different from what I have written above. When a doctor tells a patient he had a concussion, without pointing out that his neurological exam is perfectly normal and his prognosis is excellent (whether he thinks he was unconscious or not), a bag of worms is opened up. He goes home and tells his wife that the doctor said he had a concussion, she tells her friends, there are questions about any headaches or behavior changes (nocebos, Thing 54), and so on, and when the doctor sees the patient next week he’s full of subjective symptoms that are not explainable on a physical basis, and disability may have set in already. There are exceptions to this, but in head injuries we must be particularly careful what we say.
Mittenberg et al. (1992) showed that “Imaginary concussion reliably showed expectations in controls of a coherent cluster of symptoms virtually identical to the post-concussion syndrome reported by patients with head trauma.”