Retrograde amnesia is the temporary or permanent forgetting of things that occur before the event where amnesia was caused, which is often some type of brain injury. This form of amnesia can cover a a small or large portion of a person’s life and, in severe forms, might include the amnesiac’s inability to recognize loved ones or remember how to do things in which he was expert. It usually doesn’t mean forgetting everything, and it also doesn’t have to fully extend very far back through a person’s life. Some people can have mild retrograde amnesia and simply have no recall of events a few hours preceding the event resulting in the amnesiac condition.
There are many forms of amnesia, but retrograde amnesia is often contrasted to anterograde amnesia. The latter is when people have trouble remembering things after some form of trauma or some treatments like drug therapy have occurred. They might have total recall of all events prior to the memory-impairing event or some people experience retrograde and anterograde amnesia at the same time. In other words, memory before and after trauma or treatment is impaired to a certain degree.
Causes of retrograde amnesia are generally attributed to injuries in the brain, particularly the hippocampus and less specifically the temporal lobes. The ability of a person to recover from such damage largely depends on how well these regions can heal, and with severe cases, recovery isn’t always predictable. There isn't a single or standard treatment for this condition, though a number of treatments might be attempteed to help a person regain their memory. Most important, though, is doing everything possible to promote brain healing to avoid damaging the areas of the brain that appear most linked to memory.
Sometimes, very mild amnesia occurs and doesn’t require treatment. A person might have a head injury and lose a few hours before the incident, yet almost all other memory remains intact. In these cases, the head injury is clearly treated, but there wouldn’t be attempts to recover the memories of the hour or two prior to the head injury, unless it was somehow important.
Similarly, some medicines given as anesthesia may result in mild amnesia before they were given. People might have no recall of being wheeled into an operating room or talking to family just before a surgery. This isn’t always retrograde amnesia. If the person was on pain or anesthetic medications prior to getting to an operating room, those medications may be responsible for altering memory.