ALERD: acute leukoencephalopathy with restricted diffusion—a newly emerging diagnosis

Acute leukoencephalopathy with restricted diffusion (ALERD) is a distinct, severe clinical-radiological syndrome characterised by encephalopathy, seizures and restricted diffusion in the subcortical white matter. ALERD is one of the infection-associated encephalopathy syndromes seen in childhood having a higher incidence of neurological sequelae. We report three cases of ALERD, all following a prodrome of fever and gastroenteritis, progressing to seizures and encephalopathy with varying outcomes. Case 1 was diagnosed as complicated dengue fever with multiple organ dysfunction syndrome (MODS), developed diffuse ALERD but improved with immunotherapy and had mild neurologic sequelae. Case 2 presented earlier, had normal initial MRI, developed diffuse ALERD later and had significant neurologic sequelae. Case 3, despite the central-sparing pattern, had rapid progression, MODS and severe cardiac dysfunction, and ultimately succumbed to death due to aspiration. These cases underscore ALERD as a significant cause of acute encephalopathy, requiring a high index of suspicion and prompt initiation of immunotherapy for better outcomes.