Functional connectivity of the default mode, dorsal attention and fronto-parietal executive control networks in glial tumor patients.

PURPOSE: Resting state functional magnetic resonance imaging (rsfMRI) is an emerging tool to explore the functional connectivity of different brain regions. We aimed to assess the disruption of functional connectivity of the Default Mode Network (DMN), Dorsal Attention Network(DAN) and Fronto-Parietal Network (FPN) in patients with glial tumors. METHODS: rsfMRI data acquired on 3T-MR of treatment-naive glioma patients prospectively recruited (2015-2019) and matched controls from the 1000 functional-connectomes-project were analyzed using the CONN functional toolbox. Seed-Based Connectivity Analysis (SBCA) and Independent Component Analysis (ICA, with 10 to 100 components) were performed to study reliably the three networks of interest. RESULTS: 35 patients with gliomas (17 WHO grade I-II, 18 grade III-IV) and 70 controls were included. Global increased DMN connectivity was consistently found with SBCA and ICA in patients compared to controls (Cluster1: Precuneus, height: p < 10-6; Cluster2: subcallosum; height: p < 10-5). However, an area of decreased connectivity was found in the posterior corpus callosum, particularly in high-grade gliomas (height: p < 10-5). The DAN demonstrated small areas of increased connectivity in frontal and occipital regions (height: p < 10-6). For the FPN, increased connectivity was noted in the precuneus, posterior cingulate gyrus, and frontal cortex. No difference in the connectivity of the networks of interest was demonstrated between low- and high-grade gliomas, as well as when stratified by their IDH1-R132H (isocitrate dehydrogenase) mutation status. CONCLUSION: Altered functional connectivity is reliably found with SBCA and ICA in the DMN, DAN, and FPN in glioma patients, possibly explained by decreased connectivity between the cerebral hemispheres across the corpus callosum due to disruption of the connections.

Cranial nerve VI palsy in chronic sphenoid sinusitis.

Sphenoid sinusitis is a rare disease associated with life-threatening complications that can be avoided with early recognition and timely treatment. Here, we present a case of a woman in her 80s admitted for symptomatic anaemia likely secondary to a gastrointestinal bleed with left cranial nerve (CN) VI palsy incidentally discovered on physical examination. CT and MRI were suggestive of chronic left sphenoid sinusitis with possible involvement of the left cavernous sinus. Surgical treatment was deferred due to high cardiac risk for perioperative mortality and recent ischaemic stroke. Despite antibiotic treatment, the patient's CN VI palsy remained unchanged. This report contributes to the current understanding of sphenoid sinusitis by presenting a complex case of chronic sphenoid sinusitis in which urgent surgical intervention was deferred due to the patient's multiple comorbidities. Furthermore, it highlighted the importance of the CN examination and imaging modalities in diagnosing sphenoid sinusitis.