"CHANTER likely represents a severe form of acute opioid-induced neurotoxicity falling within a pathophysiologic spectrum that includes paediatric opioid use‐associated neurotoxicity with cerebellar oedema (POUNCE) syndrome (which occurs in children) and opioid-associated amnestic syndrome (which involves the hippocampi alone) 2. It is most commonly seen in the setting of fentanyl overdose 2."
"In addition to cerebellar oedema, with or without obstructive hydrocephalus, MRI demonstrates bilateral, symmetric restricted diffusion in the grey matter of the cerebellum and hippocampi, as well as asymmetric involvement of the basal ganglia 1,2. Although initially the cerebral cortex was reported as being spared 1, subsequenly published cases do include occasional cortical involvement, particularly in the occipital poles 2. Subcortical white matter involvement is uncommon 1,2."
"Prognosis is dependent on the degree to which the above therapies are able to prevent brainstem compression and herniation. If successful some patients make a near-complete recovery whereas others remain debilitated by memory, motor and speech deficits 1,2."