Acute Leukoencephalopathy with Restricted Diffusion Following Dehydration in Infant: A case report

Background: Acute Leukoencephalopathy with Restricted Diffusion (ALERD) is a rare, often underrecognized cause of encephalopathy in children. It is most commonly associated with infections or systemic inflammatory conditions, and typically presents with a biphasic clinical course. Although infection-related triggers are well documented, non-infectious causes such as dehydration are less frequently reported. This case is notable for demonstrating ALERD in an infant following severe dehydration due to acute gastroenteritis, with a central-sparing MRI pattern and complete recovery. Case presentation: We report a case of a 6-month-old female infant who presented with acute gastroenteritis and signs of severe dehydration. She initially responded to fluid resuscitation and conservative management but developed recurrent generalized tonic-clonic seizures on the third and fourth days of admission. Neurologically, the child exhibited lethargy, hypotonia, and decreased reflexes during interictal periods. Routine blood tests and cerebrospinal fluid analysis were non-contributory. On the sixth day of hospitalization, brain MRI revealed bilateral symmetrical diffusion restriction in the periventricular and subcortical white matter with sparing of the perisylvian cortex, consistent with the central-sparing pattern of ALERD. The clinical course was biphasic, with delayed neurological deterioration following initial improvement. With supportive neuroprotective care, seizure control, and hydration, the child made a full recovery. Follow-up imaging at three months showed complete radiological resolution without neurological sequelae. Conclusions: This case highlights dehydration as a rare but important non-infectious trigger for central-sparing ALERD in infants. It underscores the importance of considering ALERD in the differential diagnosis of pediatric encephalopathy with seizures following systemic stress, even in the absence of infection. Early neuroimaging, particularly diffusion-weighted MRI during the later part of the first week, is critical for timely diagnosis and prognostication. Recognizing the central-sparing pattern can help anticipate a favorable outcome with appropriate supportive management.