Idiopathic brain herniations in children: anatomical distribution and clinical correlation in the largest pediatric MRI series.

BACKGROUND

Idiopathic brain herniation (IBH) is a rare and underrecognized neuroimaging finding defined as focal protrusion of normal brain parenchyma through a dural defect or into a dural venous sinus without evidence of prior trauma, neurosurgery, or intracranial hypotension. Although IBH has been increasingly identified in adults, its prevalence, anatomical features, and clinical relevance in children remain poorly characterized.

PURPOSE: To evaluate the MRI characteristics, anatomical distribution, venous sinus relationships, and clinical associations of idiopathic brain herniation in a pediatric cohort.

MATERIALS AND

METHODS

This retrospective study included 19 pediatric patients (≤ 17 years) diagnosed with IBH on brain MRI between 2021 and 2025. Two pediatric neuroradiologists independently assessed the herniation site, laterality, depth, and venous sinus involvement. Clinical data were retrieved from medical records. Statistical analysis was performed using Chi-square and Cramer's V tests.

RESULTS

The most common IBH location was the precuneus (52.6%), followed by the temporal lobe (36.8%), lingual gyrus (5.3%), and occipital lobe (5.3%). Temporal IBH was strongly associated with seizures (85.7%, p = 0.0009; Cramer's V = 0.71), whereas most precuneal herniations were asymptomatic. Smooth intraluminal impressions mimicking dural venous sinus thrombosis were observed in two temporal cases (10.5%); however, venous flow was preserved in all patients. Interobserver agreement for IBH diagnosis was excellent (κ = 0.91). No patient required surgery or anticoagulation, and all follow-up MRIs showed stable lesions.

CONCLUSION

IBH in children is not always incidental. Temporal IBH shows a significant association with seizures and may represent a subtle structural correlate of pediatric epilepsy. Recognition of IBH and differentiation from dural venous sinus thrombosis are essential to prevent misdiagnosis and unnecessary anticoagulation. Conservative management appears sufficient in most pediatric cases.