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Abstract
Background Idiopathic intracranial hypertension (IIH) is a neurological condition characterized by symptomatology of elevated intracranial pressure in the absence of an identifiable cause. Transverse sinus stenosis (TSS) is also the most sensitive and specific neuroimaging feature of IIH. However, it remains poorly understood if brain volume might be related with extent of TSS.
Methods Patients with IIH were retrospectively identified from our tertiary healthcare system from 2016–2023. Quantitative neuroimaging segmentation and parcellation was completed on Brain MRIs using FreeSurfer software. Non-normalized estimated whole intracranial volume (eICV), total brain parenchymal volume, and total intracranial CSF volumes were calculated. Extent of TSS was determined using the quantitative semi-automatic measurement (QSAM) technique. Mean TSS was calculated as the mean percent stenosis of both transverse sinuses. Associations between TSS severity and eICV/CSF volume were calculated.
Results In total, 79 IIH patients met full inclusion criteria (mean age: 30.2; 86% female). Overall, there was a significant association between increasing eICV and mean TSS (P=0.028, R=0.25). Similarly, when stratifying sinus stenosis based on mild (0–33%), moderate (33–66%), severe (>66%) stenosis, there was a stepwise increase in eICV between groups (ANOVA, P=0.02). TSS severity was directly associated with total brain parenchymal volume (P=0.026, R=0.25) with no relationship between TSS stenosis and total cerebrospinal fluid volume (P=0.88, R=0.02). There was, however, a significant negative association between increasing brain volume and total intracranial CSF volume (P=0.002, R= -0.34).
Conclusion Quantitative neuroimaging brain segmentation is a novel modality supporting the conceptualization of IIH as interstitial edema related to impaired venous outflow. There was a direct association between the magnitude of transverse sinus stenosis (TSS), total intracranial volume, and total brain parenchymal volume. The causal relationship between brain volume and sinus stenosis remains unresolved.
Disclosures D. Schartz: None. A. Finkelstein: None. S. Akkipeddi: None. D. George: None. T. Furst: None. V. Dhar: None. N. Ellens: None. C. Houk: None. P. Valdes Barrera: None. Z. Williams: None. E. Vates: None. J. Zhong: None. M. Bender: None.