Falling whilst skiing, tumbling down the stairs or getting hit on the head can cause symptoms such as blurred vision, vomiting, loss of consciousness or memory for about 30 minutes. There is then a risk of mild cerebral trauma, which represents more than 90% of brain injuries admitted to hospitals. But is there really a brain lesion? Or are these symptoms merely the consequence of the violence of the shock, of which will ultimately only leave a bump behind?