Neuroimaging in FDXR-related mitochondriopathy.

Ferredoxin reductase (FDXR)-related mitochondriopathy is a rare autosomal recessive disorder caused by biallelic pathogenic variants in the FDXR gene. The clinical presentation is highly variable, ranging from isolated sensory neuropathies to severe infantile-onset encephalopathy with early demise. Neuroimaging is typically normal. However, oxidative stress in the setting of systemic infection can precipitate severe symptoms with distinct imaging manifestations, including confluent white matter signal abnormality, longitudinally extensive spinal cord lesions, and optic nerve enhancement. We describe a previously healthy and asymptomatic 2-year-old female with genetically confirmed FDXR-related mitochondriopathy who was found to have a distinct pattern of diffusion restriction, rapid parenchymal atrophy, and optic nerve changes following a respiratory illness. Early recognition and management of this rare but potentially devastating entity can help prevent vision loss and improve functional outcomes.