Reduced Dynamic Brain Activity and Functional Connectivity in Nonfunctioning Pituitary Adenomas with Visual Impairment

BACKGROUND AND PURPOSE: Visual disturbance is a major complication in nonfunctioning pituitary adenoma (NFPA) due to chiasmal compression. While neuroimaging studies have established brain dysfunction in visually impaired patients from chiasmal compression, the brain dynamic features of spontaneous activity and functional connectivity remain underexplored. This cross-sectional study aims to explore changes in temporal variability of spontaneous activity and connectivity in visually impaired patients with NFPA by resting-state functional MRI.

MATERIALS AND METHODS: Thirty-six patients with NFPA with visual impairment and 36 healthy controls were recruited and underwent resting-state fMRI scans. Dynamic amplitude of low-frequency fluctuation (dALFF) and dynamic functional connectivity (dFC) analyses were performed to assess temporal variability in brain activity and interregional communication. Associations between altered dALFF/dFC and the severity and duration of chiasmal compression, as well as visual field defect severity (quantified by mean deviation), were further evaluated.

RESULTS: Compared with healthy controls, patients with a nonfunctioning pituitary exhibited significantly reduced dALFF in the right lingual gyrus (LING) and bilateral calcarine fissure and surrounding cortex (CAL). Additionally, patients showed a significant reduction in dFC between the right LING and the bilateral precuneus. Our exploratory correlation analyses revealed that the altered dALFF values in the bilateral CAL and right LING were positively correlated with chiasmal volume, and the altered dALFF in the left CAL was negatively correlated with suprasellar extension distance. Additionally, the altered dALFF values in the bilateral CAL were positively correlated with mean deviation.

CONCLUSIONS: Patients with NFPA with visual impairment exhibited decreased temporal variability in brain activity and functional connectivity within visual-related regions, offering new insights into the neuropathologic mechanisms underlying visual disturbance in nonfunctioning pituitary adenoma.