MRI findings in pediatric idiopathic intracranial hypertension: evaluating the oculomotor nerve sheath as a potential new diagnostic marker.

purposeIdiopathic intracranial hypertension (IIH) in the pediatric population remains diagnostically challenging, particularly in the absence of papilledema, and increasingly depends on ancillary neuroimaging findings to support clinical assessment. The aim of this study was to systematically evaluate established magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) markers of elevated intracranial pressure in children and to investigate oculomotor nerve cistern (OMC) distention as a potential novel adjunctive imaging biomarker of pediatric IIH.

methodsThis retrospective study included patients aged 0-18 years who underwent brain MRI and contrast-enhanced MRV for suspected intracranial hypertension and had cerebrospinal fluid (CSF) opening pressure measured by lumbar puncture. Patients with secondary causes of intracranial hypertension were excluded. MRI and MRV examinations were independently assessed by two blinded senior pediatric radiologists. Imaging parameters analyzed included pituitary gland height and superior contour, perioptic CSF distention with optic nerve sheath diameter (ONSD) measurements, optic nerve tortuosity, posterior globe flattening, Meckel's cave dimensions, transverse sinus stenosis, jugular vein stenosis, and qualitative assessment of OMC distention. Patients were stratified according to CSF opening pressure, with values ≥28 cm H

resultsSixty-six patients met the inclusion criteria, of whom 44 demonstrated elevated CSF opening pressure. The mean ONSD was significantly greater in the elevated-pressure group compared with controls (5.60 ± 0.91 mm vs 5.04 ± 0.68 mm; p=0.012), and perioptic CSF distention exhibited the highest diagnostic sensitivity (90.9%). OMC distention was more frequently observed in patients with elevated CSF pressure (52.3% vs 27.3%), yielding moderate sensitivity (52.2%) and specificity (72.7%). Additionally, the anteroposterior diameter of Meckel's cave was significantly increased in the elevated-pressure cohort.

conclusionConventional MRI and MRV markers provide robust supportive evidence for the diagnosis of pediatric IIH. OMC distention appears to be a plausible adjunctive imaging biomarker that may enhance diagnostic confidence when interpreted in conjunction with established neuroimaging findings.