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Concussion can be caused by body hits too


Because concussion is a type of mild traumatic brain injury (TBI), it’s often assumed there must be a blow to the head to cause its effects.

But that is not the case. In concussion, injury to the brain occurs when there is sudden acceleration or deceleration of the brain inside the skull, where it hits the side of the skull and/or twists on itself or deforms its shape, causing damage.

So anything that causes the brain to rapidly change direction with a big force of energy may cause concussion. That could be a sharp or dull blow to the head, a hit to the jaw, whiplash, or a tackle to the body.

"It’s easier to generate a lot of acceleration if there’s a hit to the head, but you still generate acceleration of the head when you tackle someone across the chest," says Professor Mike O’Sullivan, neurologist and concussion researcher at QBI.

"I saw a bit of that in rugby union – people who definitely had concussion or head injury-related symptoms. When I saw the video, there was no actual contact to the head, but they had obvious head acceleration or change of direction from a body impact."

It’s less common to have a brain injury that doesn’t involve a hit to the head, says Professor O'Sullivan, because it’s hard to generate that much movement of the brain when the neck, shoulders and body also absorb energy from an impact.

However, concussion still should be considered in sporting situations if a player has the symptoms but no obvious impact to the head.