Postoperative Cognitive Alterations and Functional Brain Reorganization in Children With Middle Cranial Fossa Arachnoid Cysts: A Pilot fMRI Study

BACKGROUND AND OBJECTIVES: Middle fossa arachnoid cysts (MFACs) are congenital benign lesions for which the indication for surgical intervention remains controversial. Although numerous studies have demonstrated that surgery can improve cognitive function in affected children, investigations into the neural mechanisms underlying these improvements are scarce. Our aim was to quantify neurocognitive outcomes and functional brain network alterations before and after microsurgical fenestration of MFAC in children. METHODS: We acquired resting-state functional MRI data from 18 pediatric MFAC patients both preoperatively and at a mean of half year postoperatively, and obtained preoperative and postoperative cognitive test scores in 13 of these children. Twelve age-matched and sex-matched healthy participants served as controls. As primary outcome measures, we computed the amplitude of blood oxygen level–dependent fluctuations across multiple frequency bands and seed-based functional connectivity within the contralateral hemisphere. RESULTS: We observed significant postoperative improvements in cognitive function among the children. Neuroimaging demonstrated that spontaneous neural activity and functional‐connectivity strength were reduced across multiple frequency bands in the contralateral hemisphere—changes that may correlate the observed cognitive gains. By contrast, preoperative comparisons with healthy controls revealed elevated spontaneous activity and enhanced connectivity across the same bands in patients' contralateral hemispheres. These findings suggest that surgical decompression induces large‐scale reorganization of brain networks, promoting normalization of neural function, potentially through cross‐frequency modulation. CONCLUSION: Microsurgical decompression of MFAC in children yields cognitive improvements and drives large‐scale network reorganization, normalizing contralateral hyperactivation through cross-frequency modulation. These findings support surgical consideration even in minimally symptomatic cases, though further studies with larger cohorts are warranted.