It will occur due to any kind of accident or blow over head, which leads profuse bleeding from head either internal or external. That form hematoma (clots), tumors, blockage, etc that may cause convulsions, paralysis, loss of vision, loss of sensation in any part of body, etc
What happen in injury that may leads to clotting internally? After injury body try to heal the affected side, so bleeding more on that side which help to heal it fast & that may lead to clotting over it was good to blood clotting but not for brain & heart that leads other problems so we need to dissolved them.
How Homeopathy helps to make you out of this? Some Homeopathic remedies have power to dissolved blood clots in anywhere it in your body, after head injury it may cause memory loss or vision loss like etc, which can be treatable with Homeopathy, that may lead to increased memory power very nicely without any side effects