A primary brain injury results from a severe brain injury that occurs suddenly. When it occurs, it is regarded as more or less complete and may either be closed or penetrating. This typically occurs after a shooting, fall, or car accident. A secondary brain injury, on the other hand, describes the status of the brain as it changes over the subsequent hours and days after the accident. The extent of secondary brain damage is determined by changes in the brain’s cellular, chemical, blood-vascular, and tissue components. Second Impact Syndrome, often known as SIS, is connected to secondary brain damage that results from repeated brain trauma. Second Impact Syndrome serves as a cautionary tale about the importance of taking concussions and other head injuries seriously to promote healing and stop further harm.