The main danger after a head injury is intracranial hemorrhage, most of which occurs within 24 hours. However, there are some head injuries in which the lesion that damages the blood vessel exists in two ways. If the endothelium of the blood vessel is damaged, it will cause a kind of post-traumatic cerebral infarction, and it often takes a few days for the symptoms to appear after the blood vessel is completely occluded; there is also a situation where it will cause a pseudoaneurysm, and as long as the pseudoaneurysm has not been broken, it will not show any symptoms at that time. If the blood vessel is not broken at that time, the treatment is awake, and then suddenly bleeding occurs, and after angiography, it is found to be a ruptured aneurysm bleeding. Therefore, no matter how long it has been since the trauma, as long as there are symptoms, you should go for a timely review, and the doctor will choose whether to do angiography, CT, or MRI according to the situation.