Retrograde Amnesia

Retrograde amnesia (from Latin retro – backward, gradus – step, and Greek amnesia – forgetting) is a specific memory disorder in which an individual completely or partially loses the ability to recall events occurring just before experiencing a traumatic brain injury.

Etiology and pathophysiology

The formation of any memory is a complex electrochemical process. Initially, information enters short-term memory, after which brain structures (primarily the hippocampus) recode it and store it in long-term storage. The process of transition is called memory consolidation and requires a certain amount of time.

At the moment of a severe head impact, powerful bioelectrical and metabolic impulses spread across the brain. Due to the abrupt concussion of the brain, the process of consolidation is immediately and grossly interrupted. Events that occurred minutes or hours before the trauma simply do not have the chance to undergo consolidation. In contrast to old, well-rooted memories that remain intact, recent information is erased.

Clinical significance

This type of amnesia is the main and most reliable clinical sign of a concussion. The patient may be conscious, respond appropriately to questions, but may not remember the moment of the impact or the preceding circumstances.

The duration of the period wiped from memory (ranging from a few seconds to several days) directly correlates with the severity of the sustained trauma. It is important to understand that the lost memories of the moment of injury usually never return. Doctors do not attempt to treat the amnesia itself; it solely serves as a crucial diagnostic marker for assessing the degree of nervous system damage.