Most head injuries, even ones that look alarming, are managed without surgery — with observation, imaging and monitoring for warning signs. Surgery becomes necessary when there is bleeding inside the skull that is building pressure on the brain, a significant skull fracture pressing on brain tissue, or swelling severe enough to threaten the brain's blood supply.
In these situations, timing matters more than almost anything else. A blood clot pressing on the brain (a haematoma) that is evacuated within a narrow window has a very different outlook to one addressed after the brain has already been damaged by sustained pressure. This is why severe head injury is treated as a race against time from the moment a patient reaches the hospital — rapid imaging, rapid decision-making, and surgery without delay when it is indicated.
For families, the practical takeaway is simple: any head injury with worsening headache, repeated vomiting, drowsiness, confusion or a seizure needs emergency evaluation, not a wait-and-see approach at home.