Cluster of an Unusual Amnestic Syndrome Associated with Substance Use — Massachusetts, 2012–2016

In a recent communication in CDC’s Morbidity and Mortality Weekly Reports, Barash, Somerville, and DeMaria identified an unusual cluster involving 14 cases of recent, complete bilateral hippocampal ischemia on MRI. All patients presented to hospitals in eastern Massachusetts between 2012 and 2016. There was a strong history of substance use in these patients, and 13 of the 14 patients had either a history of opioid use or a positive toxicology screen for opioids on presentation. Extrahippocampal involvement was noted in a number of the cases. The clustering, relatively young age (19–52 years), and significant substance use associated of these patients warrants, according to MMWR, “broader surveillance … to determine whether this represents an emerging syndrome related to substance use or other causes, including introduction of a toxic substance.”

Radiologists that identify similar cases or have questions are urged to contact Dr. Jed Barash (

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