MRI-based evaluation of cerebrospinal fluid dynamics and optic nerve subarachnoid space alterations in idiopathic intracranial hypertension and normal tension glaucoma: a systematic review

BACKGROUND: Idiopathic intracranial hypertension (IIH) and normal tension glaucoma (NTG) are optic nerve-related disorders linked to cerebrospinal fluid (CSF) abnormalities but driven by distinct mechanisms. Continuity between the intracranial and optic nerve subarachnoid spaces allows CSF pressure and flow alterations to affect the optic nerve. This study aims to evaluate optic nerve subarachnoid space structure and CSF dynamics. METHODS: The Protocol was registered in the PROSPERO database (CRD420251267099). A systematic literature search of PubMed, Springer Nature, ScienceDirect, Scopus, and Web of Science was performed for studies published between 2010 and 2025. Two independent reviewers screened titles, abstracts, and full texts using predefined PECO criteria, resulting in the inclusion of 13 studies. Data were extracted using a standardized form capturing study characteristics, MRI methodologies, and key findings. RESULTS: Magnetic Resonance Imaging (MRI) demonstrates distinct CSF-optic nerve imaging patterns in NTG and IIH. NTG is characterized by impaired CSF dynamics, narrowing of the optic nerve sheath, and optic nerve kinking, consistent with reduced CSF pressure. In contrast, IIH shows optic nerve sheath distension, posterior globe flattening, and pituitary gland flattening, reflecting elevated intracranial pressure. In addition to conventional T1- and T2-weighted sequences, STIR, and HASTE imaging, advanced MRI techniques such as diffusion-weighted imaging, 4D flow MRI, and functional MRI enable the detection of subtle CSF flow alterations, supporting their potential role as non-invasive imaging biomarkers. CONCLUSION: MRI provides valuable insights into alterations in peri-optic cerebrospinal fluid dynamics and optic nerve morphology observed in idiopathic intracranial hypertension and normal tension glaucoma. Although these conditions are typically differentiated clinically, MRI findings may contribute to understanding disease mechanisms and may serve as supportive imaging markers.