Mixed Presentation of Heroin-Associated Spongiform Leukoencephalopathy and CHANTER Syndrome After Fentanyl Use: A Case Report

BACKGROUND: Toxic leukoencephalopathy is a heterogenous syndrome characterized by destruction of brain white matter. Inhalational heroin has been linked to a specific set of neuroimaging findings termed heroin-associated spongiform leukoencephalopathy (HSLE). Clinical findings in HSLE generally develop and progress through an initial, intermediate, and terminal stage. Fentanyl has been linked to a separate set of neuroimaging findings and neurological symptoms labeled Cerebellar Hippocampal And Basal Ganglia Transient Edema with Restriction (CHANTER) syndrome, in which patients often present with an acute onset of stupor or coma hours to days after opioid use. Fentanyl has also been documented to cause a constellation of white matter changes mirroring HSLE. CASE SUMMARY: A 50-year-old man presented with an acute onset of somnolence, dysarthria, and ataxia following a subacute history of headaches, memory deficits, weight loss, and diaphoresis. He endorsed regular fentanyl use though details about quantity and route of administration remained unclear. Brain imaging suggested a mixed picture as findings were consistent with both HSLE and CHANTER syndrome. The patient's clinical course fluctuated until 3 weeks after admission, when he began showing signs of the terminal stage of HSLE, ultimately resulting in death 1 week later. CONCLUSIONS: HSLE and CHANTER syndrome have not previously been reported as occurring concurrently, nor has fentanyl previously been linked to HSLE. This case highlights the potential for HSLE and CHANTER syndrome to coexist and for fentanyl to cause a set of findings consistent with both syndromes. The patient's spouse provided written and verbal consent to publish the information in this report.