Neuroimaging in cerebral folate deficiencies

Cerebral folate deficiency refers to neurological disorders associated with a reduced cerebrospinal fluid (CSF) concentration of 5-methyltetrahydrofolate (5-MTHF), arising from primary defects in folate transport or metabolism, or secondarily from acquired or other inherited conditions. Clinical presentation ranges from infancy to adulthood, with manifestations including developmental delay, seizures, cognitive impairment, and neuropsychiatric symptoms. Folate plays a central role in one-carbon metabolism, requiring interaction with other B-vitamins, most notably vitamin B12, to support nucleotide synthesis, methylation reactions, and myelin production. Disruption of folate-dependent pathways contributes to the imaging findings of cerebral folate deficiencies, which include abnormal white matter, calcifications, cerebral or cerebellar atrophy, and in some cases, stroke, or stroke-like lesions. This review outlines folate biochemistry, transport mechanisms into the central nervous system, and associated genetic defects, followed by a discussion of imaging features in primary and secondary cerebral folate deficiencies. Relevant differential diagnoses, particularly cobalamin-related disorders, are also examined. Importantly, many cerebral folate deficiencies are potentially reversible with timely recognition and therapy, underscoring the important role of neuroimaging in diagnosis and follow-up of these disorders.