Microstructural White Matter Alterations in Pediatric Idiopathic Intracranial Hypertension: A Diffusion Tensor...

Background/Objectives: Idiopathic intracranial hypertension (IIH) is an uncommon but clinically important cause of elevated intracranial pressure in children. Conventional MRI findings such as perioptic subarachnoid space (SAS) distension and posterior globe flattening are helpful but may lack sensitivity or specificity in certain cases. Diffusion tensor imaging (DTI), which quantifies white matter microstructure through metrics such as fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), offers additional diagnostic potential, yet its role in pediatric IIH remains insufficiently defined. Methods: This retrospective case-control study included 26 pediatric patients with IIH and 26 age- and sex-matched controls who underwent brain MRI with DTI between 2010 and 2025. DTI parameters were measured in major white matter tracts, and conventional MRI findings associated with raised intracranial pressure were recorded. Associations between DTI metrics and conventional imaging markers were analyzed using standardized statistical tests. Results: Children with IIH demonstrated significantly reduced FA and increased MD and RD values in several key white matter regions, particularly within the optic radiation, splenium of the corpus callosum, and posterior limb of the internal capsule. FA values showed a negative correlation with perioptic SAS width, while RD and MD were positively correlated with posterior globe flattening and empty sella grade. Receiver operating characteristic analysis identified FA in the optic radiation as the strongest discriminator between IIH and controls (AUC = 0.83). Inter-observer reliability for FA measurements was excellent (ICC = 0.91). Conclusions: Pediatric IIH appears to be associated with pressure-related microstructural alterations in white matter, detectable through DTI. Among the diffusion metrics, FA demonstrated the strongest diagnostic potential and may serve as a complementary tool to conventional MRI. Validation in larger, prospective pediatric cohorts is required to establish its clinical utility.