Fatal Presentation of Leigh Syndrome in a Neonate: Comprehensive Neuroimaging Findings With MT-ND5 Mutation.

Leigh syndrome represents a severe mitochondrial disorder characterized by progressive neurodegeneration, typically manifesting in infancy with devastating outcomes. We present a 30-day-old male infant who presented with acute neurological deterioration, including seizures, dystonia, and respiratory failure. Laboratory evaluation revealed elevated levels of lactate and pyruvate. Brain magnetic resonance imaging (MRI) demonstrated characteristic bilateral symmetric T2 hyperintensity with restricted diffusion involving the basal ganglia, thalami, brainstem structures, and multiple other regions. Single-voxel spectroscopy confirmed an elevated lactate peak in the basal ganglia. Genetic testing identified a 95% heteroplasmic pathogenic variant in MT-ND5, confirming mitochondrial DNA-associated Leigh syndrome. Despite intensive supportive care including mechanical ventilation and anticonvulsant therapy, the patient's condition progressively deteriorated, resulting in death 16 days after admission. This case highlights the fulminant presentation of neonatal Leigh syndrome and emphasizes the critical role of neuroimaging in establishing this diagnosis, particularly when combined with biochemical and genetic findings.