Ultrasound for Posterior Globe Flattening in Idiopathic Intracranial Hypertension: Pilot Study

Idiopathic intracranial hypertension (IIH) is a rare disorder, primarily affecting obese women of reproductive age, characterized by elevated intracranial pressure without detectable mass lesions or hydrocephalus. It presents with symptoms like headaches, visual disturbances, and diplopia. Diagnosis is based on the revised Friedman criteria, which consider papilledema, elevated lumbar puncture opening pressure, and exclusion of other causes through neuroimaging and cerebrospinal fluid (CSF) analysis. Posterior globe flattening (PGF) is a neuroimaging marker of IIH, traditionally assessed through qualitative neuroradiological evaluation. This pilot study aimed to evaluate the potential of transorbital B-mode ultrasound in detecting and quantifying PGF in IIH patients. Using a novel angular measurement, the Posterior Globe Angle (PGA), researchers compared 31 IIH patients to 28 healthy controls in a prospective case-control design. The PGA was measured at a fixed distance from the optic nerve, with angle legs tangentially aligned to the vitreous body. Results revealed that PGF was present in 39% of IIH patients and absent in controls, with PGA3mm measurements significantly higher in IIH patients (116.5° ± 5.5) than in controls (111.7° ± 2.9). A PGA3mm cutoff of ≥118.5° achieved 100% specificity and 37.5% sensitivity in distinguishing IIH from controls. These findings suggest transorbital ultrasound is a promising non-invasive tool for detecting and quantifying PGF in IIH. However, larger, multicenter studies with blinded designs are necessary to validate its diagnostic accuracy and clinical applicability.