====== Cerebrospinal fluid dynamics ======

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===== Cerebrospinal fluid motion =====

see [[Cerebrospinal fluid motion]].

===== Cerebrospinal fluid flow =====

Although CSF dynamics has been studied for an entire century, many of its aspects are still insufficiently understood. Today there are two hypotheses on [[cerebrospinal fluid physiology]]
((Bateman GA, Brown KM. The measurement of CSF flow through the aqueduct in normal and hydrocephalic children: from where does it come, to where does it go? Childs Nerv Syst. 2012 Jan;28(1):55-63. doi: 10.1007/s00381-011-1617-4. Epub 2011 Oct 27. PMID: 22038153.))
((Naidich TP, Castillo M, Cha S, Smirniototpoulos JG. Imaging of the brain. Philadelphia: Saunders Elsevier; 2013.))
: a) traditional [[hypothesis]] and b) microcirculatory/microvessel hypothesis.

[[Cerebrospinal fluid Secretion]]

[[Cerebrospinal fluid Circulation]]	

[[Cerebrospinal fluid Absorption]]	


===== Studies =====

[[Cerebrospinal fluid flow studies]].

===== Foramen Magnum flow =====

Both fast cine-PC and [[pencil beam]] imaging demonstrated expected changes in CSF flow with Valsalva maneuver in healthy participants. The real-time capability of pencil-beam imaging may be necessary to detect Valsalva-related transient CSF flow obstruction in patients with pathologic conditions such as Chiari I malformation
((Bhadelia RA, Madan N, Zhao Y, Wagshul ME, Heilman C, Butler JP, Patz S.
Physiology-based MR imaging assessment of CSF flow at the foramen magnum with a
valsalva maneuver. AJNR Am J Neuroradiol. 2013 Sep;34(9):1857-62. doi:
10.3174/ajnr.A3509. Epub 2013 Apr 25. PubMed PMID: 23620074.
)).

Real-time MR imaging noninvasively showed a transient decrease in CSF flow across the [[foramen magnum]] after coughing in symptomatic patients with [[Chiari I malformation]], a phenomenon not seen in healthy participants. The results provide preliminary evidence that the physiology-based imaging method used here has the potential to be an objective clinical test to differentiate symptomatic from asymptomatic patients with Chiari I malformation
((Bhadelia RA, Patz S, Heilman C, Khatami D, Kasper E, Zhao Y, Madan N.
Cough-Associated Changes in CSF Flow in Chiari I Malformation Evaluated by
Real-Time MRI. AJNR Am J Neuroradiol. 2015 Dec 24. [Epub ahead of print] PubMed
PMID: 26705321.
)).
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Disturbed cerebrospinal fluid (CSF) dynamics are part of the pathophysiology of normal pressure hydrocephalus (NPH) and can be modified and treated with shunt surgery.
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[[Intracranial pressure]] (ICP) pulsations are generally considered a passive result of the [[pulsatility]] of [[blood flow]]. Active experimental modification of ICP pulsations would allow investigation of potential active effects on [[blood flow]] and [[cerebrospinal fluid flow]] and potentially create a new platform for the treatment of acute and chronic low blood flow states as well as a method of CSF substance clearance and delivery. 
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The motion of cerebrospinal fluid (CSF) within the subarachnoid space and ventricles is greatly modulated when propagating synchronously with the cardiac pulse and respiratory cycle and path through the nerves, blood vessels, and arachnoid trabeculae. Water molecule movement that propagates between two spaces via a stoma, foramen, or duct presents increased acceleration when passing through a narrow area and can exhibit "turbulence." Recently, neurosurgeons have started to perform fenestration procedures using neuroendoscopy to treat hydrocephalus and cystic lesions. As part of the postoperative evaluation, a noninvasive diagnostic technique to visualize the water molecules at the fenestrated site is necessary. Because turbulence is observed at this fenestrated site, an imaging technique appropriate for observing this turbulence is essential. We therefore investigated the usefulness of a dynamic improved motion-sensitized driven-equilibrium steady-state free precession (Dynamic iMSDE SSFP) sequence of magnetic resonance imaging that is superior for ascertaining turbulent motions in healthy volunteers and patients. Images of Dynamic iMSDE SSFP from volunteers revealed that CSF motion at the ventral surface of the brainstem and the third ventricle is augmented and turbulent. Moreover, our findings confirmed that this technique is useful for evaluating treatments that utilize neuroendoscopy. As a result, Dynamic iMSDE SSFP, a simple sequence for visualizing CSF motion, entails a short imaging time, can extensively visualize CSF motion, does not require additional processes such as labeling or trigger setting, and is anticipated to have wide-ranging clinical applications in the future
((Atsumi H, Horie T, Kajihara N, Sunaga A, Sakakibara Y, Matsumae M. Simple Identification of Cerebrospinal Fluid Turbulent Motion Using a Dynamic Improved Motion-sensitized Driven-equilibrium Steady-state Free Precession Method Applied to Various Types of Cerebrospinal Fluid Motion Disturbance. Neurol Med Chir (Tokyo). 2020 Jan 15;60(1):30-36. doi: 10.2176/nmc.oa.2019-0170. Epub 2019 Nov 27. PMID: 31776307; PMCID: PMC6970069.)).