Complete Hippocampal Ischemic Amnesic Ischemic Syndrome: a newly discovered type of amnesia

Not much is yet known about this disorder, but everything seems to indicate that it is associated with drugs.

In 2012, a 22-year-old boy was brought to a Massachusetts hospital, afflicted with leg problems and what was at first thought to be a high level of confusion. He was constantly repeating the same phrases and asking the same questions. After several tests, it soon became apparent that what was what was considered confusion was in fact severe amnesia..

This had appeared suddenly and was associated with the consumption, the night before admission, of what the young man believed to be heroin. Since then, about 16 similar cases of what has come to be considered a new amnesic syndrome associated with opioid use have been detected.

What is this syndrome?

The complete hippocampal ischemic amnesic amnesic syndromeas it has been called for the time being by the doctors who discovered its existence, is characterized by the presence of the abrupt onset of anterograde amnesia, often shortly after consumption or after surviving an overdose of some type of opiate (heroin and/or fentanyl being the most frequent).

This means that patients lose the ability to record new information and store it in memory. Beyond memory problems, sufferers of this syndrome may have other alterations, but they do not define this syndrome. In some cases there has been an improvement with the passage of time (as occurred with the first of the known cases), recovering to a large extent the memory capacity to record new information.

At the neuropsychological level, the existence of brain damage in a very specific area has been observed, this aspect being the most striking (since they do not tend to have large brain lesions in other areas).This aspect is what is most striking (since they do not tend to have large brain lesions in other areas): the major damage and the most characteristic of this syndrome is the presence of a major lesion in both hippocampi, the lesion being bilateral.

The suffering of amnesia due to damage in the hippocampus or in different areas is not so unusual, and it is also known that hypoxia and stroke affect the hippocampus to a greater extent than other regions but it is not as but it is not so easy for damage to occur in both hippocampi at the same time in such a sudden way and without some kind of trauma that also damages other areas.

Causes?

The causes of the appearance of massive lesions in both hippocampi and the appearance of this type of amnesia are largely unknown. However, the immediate cause, the trigger, seems to be associated with the aforementioned opioid use. In many of the cases, the patients had a history of opioid use (especially heroin), suffering from a substance abuse disorder. (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 has been observed by analysis.

Another element to take into account is that most of the patients are more or less young (mostly between twenty and fifty), of whom around half of the known cases suffer from some vascular alteration such as hypertension or diabetes. Vascular disorders could facilitate the onset of ischemia, leading to hippocampal damage. that cause hippocampal damage, but how they are actually related is poorly understood.

Having a substance use dependence or 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 to use after the amnesic episode.

A little-known amnesic syndrome

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 same characteristics.

However, we must bear in mind that it is possible that there are more, since there is a possibility that people without resources may not have gone to the hospital (these 14 cases have been (these 14 cases have been observed in the United States), or that previous cases have been associated with other disorders.

But except for the above findings, little is known about this syndrome. Much more research is needed to determine the causes of this disorder and to establish protocols and treatment and to establish protocols for action and treatment more appropriate to this problem.

Bibliographic references:

• Barash, J.A.; Somerville, N. & DeMaria, A. (2017). Cluster of an unusual amnestic syndrome - Massachusetts, 2012-2016. MMWR.: 66(3); 76-79.
• Duru, U.B.; Pawat, G.; Barash, J.A.; Miller, L.E.; Thiruselvam, I.K. & Haut, M.W.. (2018). An Unusual Amnestic Syndrome Associated With Combined Fentanyl and Cocaine Use. Annals of Internal Medicine. American College of Physicians.
• Lim, C.; Alexander, M.P.; LaFleche, G.; Schnyer, D.M.; Verfaellie, M. (2004). The neurological and cognitive sequelae of cardiac arrest. Neurology, 63 (10): 1774-1778.