Define post-traumatic amnesia and explain its prognostic significance.

• A. PTA is a transient mood change after injury; longer PTA predicts better outcomes.
• B. PTA is a period of confusion without memory loss; shorter PTA predicts worse outcomes.
• C. PTA is a subjective experience of amnesia with no impact on prognosis.
• D. PTA is the period of continuous memory loss after injury; longer PTA is associated with worse cognitive and functional outcomes.

Answer: (D)

Post-traumatic amnesia is the period after a brain injury during which the person cannot form new memories and remains disoriented. It starts at the time of injury and ends when the ability to continuously recall ongoing events and new information stabilizes, meaning the person can reliably remember recent experiences and follow day-to-day events.

The longer this memory-formation window lasts, the worse the cognitive and functional prognosis tends to be. A longer PTA duration indicates more extensive brain disruption, and it typically predicts slower overall recovery, longer rehabilitation, and a greater likelihood of lasting deficits. That’s why PTA duration is a key marker used to gauge injury severity and guide prognosis and care planning.

Other descriptions that portray PTA as mood changes, confusion without memory loss, or having no impact on prognosis don’t capture the defining feature—the disruption of forming new memories—and don’t align with how PTA relates to outcomes.