Which term best describes the progression of brain injury due to hypoxia, hypotension, or swelling?

• A. Primary Brain Injury
• B. Head Injury
• C. Secondary Brain Injury
• D. Concussion

Answer: (C)

Secondary brain injury describes the progression of damage that follows the initial trauma. After the initial insult causes primary brain injury, the brain is vulnerable to further injury from systemic factors such as low oxygen (hypoxia), reduced blood flow (hypotension), or swelling that raises pressure inside the skull. These conditions deprive brain cells of oxygen and nutrients, triggering a damaging cascade: energy failure, calcium overload, excitotoxic neurotransmitter release, inflammation, edema, and free-radical injury. This cascade worsens tissue damage over hours to days, extending beyond the original injury site. By contrast, the immediate damage from trauma is the primary brain injury, while a concussion is a milder form of traumatic brain injury, and “head injury” is a broad term.