Opioid-Induced Leukoencephalopathies: A Report of Two Cases.

Acute toxic leukoencephalopathy (ATL) and delayed post-hypoxic leukoencephalopathy (DPHL) are two possible adverse entities related to opioid intoxication (OI), each having a distinct clinical course. While ATL shows a monophasic course with gradual neurological deterioration, DPHL has a distinct biphasic course. We report a case of ATL along with a case of DPHL happening in young male patients with OI, including their clinical courses as well as imaging characteristics with comparable time intervals. Initially, both leukoencephalopathies typically show magnetic resonance imaging findings with confluent and symmetric white matter (WM) abnormalities in the periventricular regions on T2 and fluid-attenuated inversion recovery images along with restricted diffusion on diffusion-weighted imaging. The DPHL patient however also presented with WM cystic substance loss in the deterioration phase, several weeks after hospital admission, which was previously described in a case of DPHL. Interestingly, similar WM changes have recently been observed in virus-associated necrotizing disseminated acute leukoencephalopathy in patients with coronavirus disease 2019 which may suggest a common pathophysiological mechanism. Knowing the distinct imaging features of ATL and DPHL along with their typical clinical courses can provide a faster and more reliable differentiation between these two entities.