You pose an interesting question.
When there is a head injury when should one go to general quarters?
The answer is not quite that clear.
Decades ago the cute female surgeon attending in an ER where I worked slipped on the ice in our parking lot and hit her head.,
"Tut, tut", she said. "Nothing significant."
She went right to work, munching on carrots. She was a vegetarian.
Three (Yes - three) weeks later she decided to have an x-ray film taken (she was experiencing headaches) and lo - she found she had a hairline fracture C3!
With injuries involving falling backwards you generally have two issues. Issue one is the blow to the head which may cause a concusion or a bleed (subdural hematoma).
The second problem is that of a subluxation - or displacement of the vertebra - which is the classical "whiplash injury" and may show up as a lifetime of chronic pain.
To cut to the chase: "How much force is necessary to cause a fracture of the vertebra or cause a subdural bleed?"
The answer is: "it depends".
A mild concusion will generally resolve on its own. In any event there is a window of opportunity to act, and if that is lost treatment a week later doesn't do much good. The swelling causes the damage.
A bleed, or subduralm hematoma USUALLY comes with a package of symptoms, but not always. They is always the non-typical presentation. An MRA is the onloy definitive means of diagnosis.
Any blow to the head resulting in sudden flexure of the next should be evaluated at a minimum by taking a film, preferably with an MRI, ASAP.
Hi
Welcome to the MedHelp forum!
Any head injury should be assessed by a doctor. Symptoms can develop immediately or even weeks later. The injury can be superficial to muscles and soft tissues and this can cause headaches and sore feeling which any pain killer can help reduce. However, the injury could be more serious.
Watch out for nausea, vomiting, excess sleep, severe persisting headache, difficulty in walking and balance, tremors, seizures, vision problems, ringing in ears etc, and if present then consult a doctor immediately. These symptoms develop if there is a brain injury or bleed.
Since I cannot examine your son, it's difficult to comment for sure whether he has suffered a serious injury or just soft tissue injury. Please consult your PCP for primary examination followed by proper referral. Take care!