Someone loses consciousness for a BRIEF MOMENT, after an impact to the head.
It could be an aged parent, who slipped and fell, hitting his/her head; a child playing with other kids, who got hit in the head; a toddler, who fell from a table, or chair; or a spouse, who received a blow to the head.
Whatever the mechanism of impact, the person loses consciousness for a brief moment, and then comes around almost immediately, with an "I am fine," and a smile of reassurance.
Well, they may not be fine, even though they look fine. While it may be "just" a concussion, the person may be experiencing what is called a LUCID INTERVAL.
A lucid interval is a period, following a brief loss of consciousness from an impact, during which the person is apparently normal, with no noticeable symptoms or sign of brain dysfunction.
This is a trap, as it creates a false sense of well being, and could be reassuring to an onlooker. A fraction of such people may have sustained an injury to the brain, and may be bleedig inside. Such people would remain normal for minutes, sometimes for hours, or even days, until the blood accumulating inside their head is enough to cause significant compression of the brain. Then they'd lose consciousness a second time, this time going into a coma, with risk of brain herniation, and DEATH.
For this reason, anyone that sustains an impact to the head, and loses consciousness-- no matter how brief the loss of consciousness, or how mild the impact-- MUST be reviewed by a doctor, and if possible do a CT scan, to rule out an occult brain bleed [ notice that I used MUST, and not SHOULD].
Do not be tricked by a lucid interval into believing that they're okay; they're not okay until we say they are!