No abstract

OBJECTIVE Transependymal flow (TEF) of CSF, often delineated as T2-weighted hyperintensity adjacent to the lateral ventricles on MRI, is a known imaging finding, usually in the setting of CSF flow disturbances. Specific radiological features of TEF and their relationships with clinical markers of hydrocephalus and underlying disease pathology are not known. Here, the authors describe the radiological features and clinical associations of TEF with implications for CSF circulation in the setting of intracranial pathology. METHODS After obtaining IRB review and approval, the authors reviewed the radiological records of all patients who underwent intracranial imaging with CT or MRI at St. Louis Children’s Hospital, St. Louis, Missouri, between 2008 and 2019 to identify individuals with TEF. Then, under direct review of imaging, TEF pattern, degree, and location and underlying pathology and other radiological and clinical features pertaining to CSF circulation and CSF disturbances were noted. RESULTS TEF of CSF was identified in 219 patients and was most prevalent in the setting of neoplasms (72%). In 69% of the overall cohort, TEF was seen adjacent to the anterior aspect of the frontal horns and the posterior aspect of the occipital horns of the lateral ventricles, and nearly half of these patients also had TEF dorsal to the third ventricle near the splenium of the corpus callosum. This pattern was independently associated with posterior fossa medulloblastoma when compared with pilocytic astrocytoma (OR 4.75, 95% CI 1.43–18.53, p = 0.0157). Patients with congenital or neonatal-onset hydrocephalus accounted for 13% of patients and were more likely to have TEF circumferentially around the ventricles without the fronto-occipital distribution. Patients who ultimately required permanent CSF diversion surgery were more likely to have the circumferential TEF pattern, a smaller degree of TEF, and a lack of papilledema at the time of CSF diversion surgery. CONCLUSIONS CSF transmigration across the ependyma is usually restricted to specific periventricular regions and is etiology specific. Certain radiological TEF characteristics are associated with tumor pathology and may reflect impaired or preserved ependymal fluid handling and global CSF circulation. These findings have implications for TEF as a disease-specific marker and in understanding CSF handling within the brain.

The Salton Sea Trough has a range of geothermal features, including mud volcanoes, pots, and seeps that express fluids at temperatures ranging from ambient to 65 to 100 C. The features produce 99% CO2/0.5% CH4 gas of a thermogenic origin and contain hydrothermally-produced petroleum. The mud/clay from the Davis-Schrimpf mud volcanoes has an elemental sulfur (S0) concentration of 317 microM, suggesting that sulfur metabolism should be important in the system. Surprisingly, there has been very little microbiological characterization of these features. Described here are microbial communities, determined by Illumina sequencing of the 515F – 806R 16S rRNA gene fragment, from mud volcanoes/seeps from the Davis-Schrimph seep field and nearby areas with surface feature temperatures from ambient, 65 C, and 100 C. In addition, we have characterized the communities that developed over 1 month at 65 C in enrichment cultures from the 65 C mud volcanoes incubated with a range of electron acceptors (ferrihydrite, S0, SO42-, and S2O32-) and electron donors (tryptone/yeast/casamino acids, crude oil, and CH3CO2-). The 65 C mud and enrichment culture communities were generally predominated by autotrophic H2-oxidizers and organotrophic H2-producers, acetogens, acetotrophs and heterotrophic S0, SO42-, and S2O32- reducers, including many relatives of microbes previously observed in the deep subsurface and from petroleum fields or production waters. While methanogens were present, they were generally at low levels, and few obvious methylotrophs or anaerobic methane oxidizers were detected. Overall, these results provide evidence for a subsurface lithoautotrophic microbial ecosystem (or SliME) in the Salton Sea trough subsurface.

Purpose Pediatric brain tumor patients often experience significant cognitive sequelae. Resting-state functional MRI (rsfMRI) provides a measure of brain network organization, and we hypothesize that pediatric brain tumor patients treated with proton therapy will demonstrate abnormal brain network architecture related to cognitive outcome and radiation dosimetry. Participants and Methods Pediatric brain tumor patients treated with proton therapy were enrolled on a prospective study of cognitive assessment using the NIH Toolbox Cognitive Domain. rsfMRI was obtained in participants able to complete unsedated MRI. Brain system segregation (BSS), a measure of brain network architecture, was calculated for the whole brain, the high-level cognition association systems, and the sensory-motor systems. Results Twenty-six participants were enrolled in the study for cognitive assessment, and 18 completed rsfMRI. There were baseline cognitive deficits in attention and inhibition and processing speed prior to radiation with worsening performance over time in multiple domains. Average BSS across the whole brain was significantly decreased in participants compared with healthy controls (1.089 and 1.101, respectively; P = 0.001). Average segregation of association systems was significantly lower in participants than in controls (P < 0.001) while there was no difference in the sensory motor networks (P = 0.70). Right hippocampus dose was associated with worse attention and inhibition (P < 0.05) and decreased segregation in the dorsal attention network (P < 0.05). Conclusion Higher mean dose to the right hippocampus correlated with worse dorsal attention network segregation and worse attention and inhibition cognitive performance. Patients demonstrated alterations in brain network organization of association systems measured with rsfMRI; however, somatosensory system segregation was no different from healthy children. Further work with preradiation rsfMRI is needed to assess the effects of surgery and presence of a tumor on brain network architecture.