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Permanent URI for this collectionhttps://hdl.handle.net/11443/932

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Subject: search.filters.subject.Optical coherence tomography

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    In Xenopus ependymal cilia drive embryonic CSF circulation and brain development independently of cardiac pulsatile forces
    (BMC, 2020-01-01) Dur, A. H.; Tang, T.; Viviano, S.; Sekuri, A.; Willsey, H. R.; Tagare, H. D.; Kahle, K. T.; Deniz, E.
    Background Hydrocephalus, the pathological expansion of the cerebrospinal fluid (CSF)-filled cerebral ventricles, is a common, deadly disease. In the adult, cardiac and respiratory forces are the main drivers of CSF flow within the brain ventricular system to remove waste and deliver nutrients. In contrast, the mechanics and functions of CSF circulation in the embryonic brain are poorly understood. This is primarily due to the lack of model systems and imaging technology to study these early time points. Here, we studied embryos of the vertebrate Xenopus with optical coherence tomography (OCT) imaging to investigate in vivo ventricular and neural development during the onset of CSF circulation. Methods Optical coherence tomography (OCT), a cross-sectional imaging modality, was used to study developing Xenopus tadpole brains and to dynamically detect in vivo ventricular morphology and CSF circulation in real-time, at micrometer resolution. The effects of immobilizing cilia and cardiac ablation were investigated. Results In Xenopus, using OCT imaging, we demonstrated that ventriculogenesis can be tracked throughout development until the beginning of metamorphosis. We found that during Xenopus embryogenesis, initially, CSF fills the primitive ventricular space and remains static, followed by the initiation of the cilia driven CSF circulation where ependymal cilia create a polarized CSF flow. No pulsatile flow was detected throughout these tailbud and early tadpole stages. As development progressed, despite the emergence of the choroid plexus in Xenopus, cardiac forces did not contribute to the CSF circulation, and ciliary flow remained the driver of the intercompartmental bidirectional flow as well as the near-wall flow. We finally showed that cilia driven flow is crucial for proper rostral development and regulated the spatial neural cell organization. Conclusions Our data support a paradigm in which Xenopus embryonic ventriculogenesis and rostral brain development are critically dependent on ependymal cilia-driven CSF flow currents that are generated independently of cardiac pulsatile forces. Our work suggests that the Xenopus ventricular system forms a complex cilia-driven CSF flow network which regulates neural cell organization. This work will redirect efforts to understand the molecular regulators of embryonic CSF flow by focusing attention on motile cilia rather than other forces relevant only to the adult.
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    Shunt Valve Rupture in Ventriculoperitoneal Shunt Failure
    (ELSEVIER SCIENCE INC, 2021-01-01) Guduk, Mustafa; Akbas, Ahmet; Tuzunalp, Muruvvet Ayten; Berikol, Gurkan; Eksi, Murat Sakir
    BACKGROUND: Shunt complications are common despite advances in surgial techniques and shunting technology. Proximal and/or distal catheter malfunctions are detected in pediatric and adult patients. However, valve dysfunction is rare in such cases. CASE DESCRIPTION: A 24-year-old woman presented with a history of veotriculostomy and ventriculoperitoneal shunt (VPS) secondary to hydrocephalus concomitant with Dandy-Walker syndrome. She has had undulant headache and vision loss episodes in both eyes for 15 days. Her VPS valve was normal when manually checked, and the VPS was observed as intact on x-ray and computed tomography scan. She had high-grade papilledema in both eyes with an optical coherence tomography scan value of 55/99. Lumbar puncture was performed. Cerebrospinal fluid opening pressure was 560 mm H2O under sedation. VPS exploration surgery was performed. There was a tiny defect over the shunt valve from where clear cerebrospinal fluid was leaking. We revised the old VPS valve with a new valve of 1.5 regular pressure. Her vision improved shortly after the surgery. CONCLUSIONS: This case is a very rare example of shunt valve dysfunction that required further investigation and a new valve replacement even though the preoperative imaging was normal.
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    Shallow Anterior Chamber in a Severe Case of Unilateral Acute Central Serous Retinal Detachment
    (KARGER, 2017-01-01) Colakoglu, Ahmet; Cosar, Banu
    Background: Atypical serous chorioretinopathy can present with symptoms similar to those of other pachychoroid diseases