Teaching NeuroImage: Opioid-Associated Amnestic Syndrome

A 36-year-old man with polysubstance use disorder presented with confusion.Examination demonstrated orientation to self only, impaired delayed recall, anterograde amnesia, and preserved remote memory.He was found to have rhabdomyolysis and troponinemia.Fentanyl, cocaine, and opiates were detected on urine drug screen.EEG showed generalized rhythmic delta activity.MRI brain the day after presentation revealed gyriform hippocampal diffusion restriction and FLAIR hyperintensity (Figure 1) consistent with opioid-associated amnestic syndrome (OAS) and a splenial FLAIR hyperintensity with potential etiologies in this clinical context including toxic/metabolic encephalopathy related to substance use and hypoxicischemic injury (Figure 2). 1 After 2 weeks of supportive care, memory improved but remained below baseline.At three-month follow-up, cognition further improved and he returned to work.OAS causes anterograde amnesia and encephalopathy and may occur after fentanyl use. 2 OAS may cause persistent cognitive deficits lasting months or longer.Although not demonstrated in this case because of absent follow-up imaging, MRI abnormalities associated with OAS often resolve.