The MOST reliable sign of a head injury is:

• A. Severe headache
• B. Decreased level of consciousness
• C. Nausea
• D. Amnesia

Answer: (B)

Decreased level of consciousness best indicates brain involvement after head trauma. Consciousness reflects how well the brain’s function is intact, particularly the cortex and the reticular activating system. A drop in alertness or responsiveness shows that the brain is not functioning normally, which is a stronger and more direct sign of injury than other symptoms. Severe headache, nausea, and amnesia can occur with many conditions or less severe head injuries and don’t always reflect the brain’s current functional state. In practice, any change in consciousness after head trauma is a red flag, requiring careful monitoring, airway support, and prompt transport for evaluation.