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Background and Objectives:Existing tools to diagnose spontaneous intracranial hypotension (SIH), namely spinal opening pressure (OP) and brain MRI, have limited sensitivity. We investigated whether evaluation of brain MRI using the Bern Score, combined with calculated craniospinal elastance, would aid in diagnosing SIH and provide insight into its pathophysiology.Methods:A retrospective chart review was performed of patients who underwent brain MRI and pressure-augmented dynamic CT myelography (dCTM) for suspicion of SIH. Two blinded Neuroradiologists assigned Bern Scores for each brain MRI. OP and incremental pressure changes after intrathecal saline infusion were recorded to calculate craniospinal elastance. The relationship between Bern Score, OP, elastance, and whether a leak was found were analyzed.Results:72 consecutive dCTMs were performed in 53 patients. 12 CSF-venous fistulae, two ruptured meningeal diverticula, two dural defects, and one dural bleb were found (17/53=32%). Among patients with imaging proven CSF leak/fistula, OP was normal in all but one patient, and was not significantly different in those with a leak compared to those without (15.1 vs 13.6 cm H2O, p = 0.24, A=0.40). Average Bern Score in individuals with a leak was significantly higher than in those without (5.35 vs 1.85, p < 0.001, A=0.85), even when excluding pachymeningeal enhancement from the score (3.77 vs 1.57, p = 0.001, A=0.78). Average elastance in those with a leak was higher than in those without, but this difference was not statistically significant (2.05 vs 1.20 mL/cm H2O, p = 0.19, A=0.40). Increased elastance was significantly associated with an increased Bern Score (p < 0.01, 95% CI -0.55, 0.12), and was significantly associated with venous distention, pachymeningeal enhancement, prepontine narrowing, and subdural collections, but not a narrowed mamillopontine or suprasellar distance.Discussion:OP is not an effective predictor for diagnosing CSF leak, and if used in isolation would result in misdiagnosis of 94% of patients in our cohort. The Bern Score was associated with a higher diagnostic yield of dCTM. Elastance was significantly associated with certain components of the Bern Score.

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OBJECTIVEFunctional connectivity magnetic resonance imaging (fcMRI) is a form of fMRI that allows for analysis of blood oxygen level–dependent signal changes within a task-free, resting paradigm. This technique has been shown to have efficacy in evaluating network connectivity changes with epilepsy. Presurgical data from patients with unilateral temporal lobe epilepsy were evaluated using the fcMRI technique to define connectivity changes within and between the diseased and healthy temporal lobes using a within-subjects design.METHODSUsing presurgical fcMRI data from pediatric patients with unilateral temporal lobe epilepsy, the authors performed seed-based analyses within the diseased and healthy temporal lobes. Connectivity within and between temporal lobe seeds was measured and compared.RESULTSIn the cohort studied, local ipsilateral temporal lobe connectivity was significantly increased on the diseased side compared to the healthy temporal lobe. Connectivity of the diseased side to the healthy side, on the other hand, was significantly reduced when compared to connectivity of the healthy side to the diseased temporal lobe. A statistically significant regression was observed when comparing the changes in local ipsilateral temporal lobe connectivity to the changes in inter–temporal lobe connectivity. A statistically significant difference was also noted in ipsilateral connectivity changes between patients with and those without mesial temporal sclerosis.CONCLUSIONSUsing fcMRI, significant changes in ipsilateral temporal lobe and inter–temporal lobe connectivity can be appreciated in unilateral temporal lobe epilepsy. Furthermore, fcMRI may have a role in the presurgical evaluation of patients with intractable temporal lobe epilepsy.

Prior studies of functional connectivity following callosotomy have disagreed in the observed effects on interhemispheric functional connectivity. These connectivity studies, in multiple electrophysiological methods and functional MRI, have found conflicting reductions in connectivity or patterns resembling typical individuals. The authors examined a case of partial anterior corpus callosum connection, where pairs of bilateral electrocorticographic electrodes had been placed over homologous regions in the left and right hemispheres. They sorted electrode pairs by whether their direct corpus callosum connection had been disconnected or preserved using diffusion tensor imaging and native anatomical MRI, and they estimated functional connectivity between pairs of electrodes over homologous regions using phase-locking value. They found no significant differences in any frequency band between pairs of electrodes that had their corpus callosum connection disconnected and those that had an intact connection. The authors’ results may imply that the corpus callosum is not an obligatory mediator of connectivity between homologous sites in opposite hemispheres. This interhemispheric synchronization may also be linked to disruption of seizure activity.