Reader Response: Amnestic Syndrome and Bilateral Hippocampal Diffusion Abnormalities From Opioid Use

Reports of opioid-associated amnestic syndrome¹ have increased with the rising use of opioids, particularly among young men.² At our institution in British Columbia, which has one of the highest rates of opioid-related hospitalizations in Canada,³ we have observed at least 3 such cases in the last 4 years with similar initial imaging. All were positive for fentanyl on urine toxicology. One of these was associated with a delayed leukoencephalopathy causing akinetic mutism, which developed roughly 3 weeks after initial presentation with isolated anterograde amnesia. Diffuse delayed leukoencephalopathy was recently reported as an unexpected outcome of acute opioid-associated amnestic syndrome.⁴ It would be interesting to know the eventual outcome in this case, and if any follow-up was provided. Monitoring for a delayed leukoencephalopathy should be considered by neurologists caring for these vulnerable patients. Prognosis should be deferred until these patients have been stable for at least 1 month after presentation.