Complete Hippocampal Ischemic Amnestic Syndrome: A Recently Discovered Type Of Amnesia
In 2012, a 22-year-old boy was taken to a Massachusetts hospital suffering from leg problems and what was initially considered a high level of confusion. He constantly repeated the same phrases and asked the same questions. After passing several tests, it was soon evident that What was considered confusion was actually severe amnesia
This had appeared suddenly, being associated with the consumption, the night before admission, of what the young man believed to be heroin. Since then, around 16 similar cases of what has come to be considered a new amnestic syndrome, associated with the use of opioids, have been detected.
Complete hippocampal ischemic amnestic syndrome as the doctors who discovered its existence have called it for the moment, is characterized by the presence of the sudden onset of anterograde amnesia, often shortly after consumption or after surviving an overdose of some type of opiate (being heroin and /or fentanyl the most common).
This means that patients lose the ability to record new information and store it in memory. Beyond memory problems, those who suffer from this syndrome may have other alterations, but they are not defining of this syndrome. In some cases there has been improvement over time (as occurred with the first of the known cases), largely recovering the memory capacity to record new information.
At a neuropsychological level, The existence of brain damage has been observed in a very specific area this aspect being what is most striking (since they do not tend to have large brain lesions in other areas): the greatest damage and the most characteristic of this obvious syndrome is the presence of a major lesion in both hippocampi, being the bilateral injury.
Suffering from amnesia due to damage to the hippocampus or different areas is not so unusual, and it is also known that hypoxia and stroke affect the hippocampus to a greater extent than to other regions, but it is not so simple for damage to occur in both hippocampi at the same time in such a sudden manner and without some type of trauma that also damages other areas.
Cause?
The causes of the appearance of massive lesions in both hippocampi and the appearance of this type of amnesia are largely unknown. Despite this, the immediate cause, the trigger, seems to be associated with the aforementioned opioid consumption. In many of the cases, the patients had a history of opioid use (especially heroin), suffering from a substance abuse disorder, and in some other cases the presence of other drugs such as cocaine, marijuana, amphetamines, hallucinogens or medications such as benzodiazepines have been observed through analysis.
Another element to take into account is that we are mostly dealing with more or less young patients (mostly between twenty and fifty), of which around half of known cases suffer from some vascular disorder such as hypertension or diabetes. Vascular alterations could facilitate the appearance of ischemia that caused hippocampal damage, but how they are really related is little known.
Suffering from a dependency or substance use disorder, in addition to being one of the possible causes or triggers, can have different repercussions for your health that can complicate your recovery if you continue using after the amnesic episode.
Not much is known about this syndrome, but it has been observed that it is undergoing some expansion: since the first case was observed in 2012 until today, a total of 16 identified cases have been detected in the United States that meet the criteria. same characteristics.
However, we must keep in mind that it is possible that there are more, since There is a possibility that people without resources have not gone to the hospital (these 14 cases have been observed in the United States), or that previous cases have been associated with other disorders.
But except for the aforementioned findings, little is known about this syndrome. Much more research is needed to determine the causes of this disorder and establish action and treatment protocols more appropriate to this problem.
