Amnesia and hippocampal ischemia in 4 opiate abusers: a case series
February 1, 2017, 12:26 am
Complete, bilateral hippocampal ischemia: a case series. Small JE et al. Neruocase 2016 Oct;22:411-415.
Last week, we reviewed an MMWR investigation into a cluster of 14 cases of acute anterograde amnesia with MRI evidence of bilateral hippocampal ischemia identified in Massachusetts during the years 2012-2016. This constellation of features is distinctly unusual — especially when symmetric and accompanied by scant pathology outside the hippocampus — but has in the past been associated with cocaine abuse and carbon monoxide poisoning.
The MMWR review contained limited clinical information. This paper, from Lahey Medical Center in Burlington MA, describes the initial 4 cases ins somewhat more detail. Some key features of these cases:
- Three patients had opiate-positive drug screens (the other had a history of opiate abuse but no drug screen was sent)
- Two patients were unresponsive when brought to hospital (the other 2 had abrupt-onset amnesia but no history of unconsciousness)
- Neurological deficits persisted to some extent on long-term follow-up in two patients (one of the others died before repeat test, the fourth did not return to clinic)
The authors propose that “MRI finding of acute pyriform ischemia in the hippocampi should be considered strongly suggestive of a toxic exposure.” While they concede that these 4 cases do not prove a causative link between abuse of any specific drug and this amnesia syndrome, this article serves as a head-up that should alert clinicians to be on the look for additional cases, and report any that are identified.