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Understanding Brain Delivery
Published in Carla Vitorino, Andreia Jorge, Alberto Pais, Nanoparticles for Brain Drug Delivery, 2021
Joana Bicker, Ana Fortuna, Gilberto Alves, Amílcar Falcäo
As previously mentioned, about two-thirds of the CSF are secreted at high capacity by four choroid plexuses in the lateral right, lateral left, third and fourth brain ventricles [36, 37]. The CSF circulates from the lateral to the third ventricle via the interventricular foramina and then to the fourth ventricle through the cerebral aqueduct. Afterwards, it flows down the central canal of the spinal cord and circulates in the subarachnoid space, where it is reabsorbed by arachnoid villi or granulations, which are valve-like structures which enable the CSF to flow out into cerebral veins when its pressure is higher than venous pressure [36]. Lastly, the CSF is directed into the systemic venous circulation or to regional and cervical lymph nodes through cranial and spinal nerves [38, 39]. Regular CSF flow is critical for balanced cerebral metabolism and propelled by several mechanisms, including arterial pulsations in the choroid plexus, a hydrostatic pressure gradient from the CSF to venous blood and the movement of ciliary processes which extend from the apical surfaces of ependymal cells [24]. The rate of production and the composition of the CSF are altered by circadian oscillations [40, 41].
Computational modeling and simulation of stenosis of the cerebral aqueduct due to brain tumor
Published in Engineering Applications of Computational Fluid Mechanics, 2022
Uzair Ul Haq, Ali Ahmed, Zartasha Mustansar, Arslan Shaukat, Sasa Cukovic, Faizan Nadeem, Saadia Talay, M. Junaid Iqbal Khan, Lee Margetts
Brain tumors can be benign or malignant. Compressive forces of the brain tumor may constrict the flow of cerebrospinal fluid (CSF), thereby causing stenosis of the cerebral aqueduct (CA). Likewise, during stenosis of the CA, obstructive hydrocephalus (which is a direct consequence of the constriction caused by brain tumor on the walls of the CA) can be seen as well. It is important to understand the core mechanisms of stenosis of the CA, and the nature, pathophysiology and biomechanics of the brain tumor and obstructive hydrocephalus, along with their relationship with each other. The study of stenosis of the CA primarily helps in understanding the increase in intracranial pressure (ICP) under particular circumstances. According to a survey conducted by CancerNet (2021), around 23,890 adults in the USA would be diagnosed with brain cancers in 2021; furthermore, every year about a million Americans are affected by hydrocephalus (Hydrocephalus Association, 2021). Stenosis of the CA is an important domain and a topical area for clinical discussion. Continuous monitoring of CSF pressure (and ICP) inside the cranium usually involves surgical interventions. The invasive mechanisms for clinically sensitive procedures are risky and cannot be performed as a matter of routine. However, a numerical model may overcome this clinical and practical limitation in a non-invasive manner. This would provide clinicians with better analytic methods to understand the interaction of the brain tumor with the walls of the CA and its effects, including stenosis, without surgical intervention.
The individual and combined effects of spaceflight radiation and microgravity on biologic systems and functional outcomes
Published in Journal of Environmental Science and Health, Part C, 2021
Jeffrey S. Willey, Richard A. Britten, Elizabeth Blaber, Candice G.T. Tahimic, Jeffrey Chancellor, Marie Mortreux, Larry D. Sanford, Angela J. Kubik, Michael D. Delp, Xiao Wen Mao
Microgravity is also a major stressor on the CNS, inducing changes in the structure of the brain (rotation of the cerebral aqueduct, changes in ventricular volume, and narrowing of cerebrospinal fluid (CSF) spaces at the vertex,142 and a cephalic fluid shift. It also produces significant effects on the brain, particularly in cerebellar, sensorimotor, and vestibular brain regions (Reviewed in 143) Brain activity may also change in response to the need for increased processing required for postural stabilization, and integration of conflicting vestibular information in the microgravity environment.144 Despite all these changes, the evidence that prolonged microgravity leads to a permanent loss of cognitive function is sparse. Astronauts report a “Space fog” for 1-2 days into a mission, but this typically resolves.