Time course of washout.

<p>Normalized gray value curves quantifying the washout process of six of the eight washout experiments, of both reference experiments and of the experiment with pulsatile conditions. For a better clearness graphs were displayed in two groups (A and B) with identical scales. The horizontal lines labeled with 100%, 50%, 25% and 12.5% represent the normalized gray values from a calibration experiment with according blood model concentrations.</p

In Vitro Study of Cerebrospinal Fluid Dynamics in a Shaken Basal Cistern after Experimental Subarachnoid Hemorrhage

<div><h3>Background</h3><p>Cerebral arterial vasospasm leads to delayed cerebral ischemia and constitutes the major delayed complication following aneurysmal subarachnoid hemorrhage. Cerebral vasospasm can be reduced by increased blood clearance from the subarachnoid space. Clinical pilot studies allow the hypothesis that the clearance of subarachnoid blood is facilitated by means of head shaking. A major obstacle for meaningful clinical studies is the lack of data on appropriate parameters of head shaking. Our <em>in vitro</em> study aims to provide these essential parameters.</p> <h3>Methodology/Principal Findings</h3><p>A model of the basal cerebral cistern was derived from human magnetic resonance imaging data. Subarachnoid hemorrhage was simulated by addition of dyed experimental blood to transparent experimental cerebrospinal fluid (CSF) filling the model of the basal cerebral cistern. Effects of various head positions and head motion settings (shaking angle amplitudes and shaking frequencies) on blood clearance were investigated using the quantitative dye washout method. Blood washout can be divided into two phases: Blood/CSF mixing and clearance. The major effect of shaking consists in better mixing of blood and CSF thereby increasing clearance rate. Without shaking, blood/CSF mixing and blood clearance in the basal cerebral cistern are hampered by differences in density and viscosity of blood and CSF. Blood clearance increases with decreased shaking frequency and with increased shaking angle amplitude. Head shaking facilitates clearance by varying the direction of gravitational force.</p> <h3>Conclusions/Significance</h3><p>From this <em>in vitro</em> study can be inferred that patient or head shaking with large shaking angles at low frequency is a promising therapeutic strategy to increase blood clearance from the subarachnoid space.</p> </div

Scheme of the influence of gravitational alignment and shaking angle.

<p>Blood model distribution images (A) and schematic drawings (B) after injection (φ = 0°, T = 0 min). The g-arrows indicate the direction of the gravitational force, blue regions correspond to experimental blood, whereas white regions to experimental CSF. Different cistern orientations (α = 0°, 30°, 90°) cause different CSF-blood layers. (C) Schematic drawings of different shaking angles for a given cistern position (α = 0°). The complex shape of the basal cistern hampers extensive movement of cisternal blood if the shaking angle is too small.</p

Anatomical data of the model cistern.

<p>Three orthogonal slices of the MRI data with cerebrospinal fluid in the cerebral sulci, ventricles, and basal cisterns indicated in pink. The three-dimensionally reconstructed basal cistern (red) and the ventricular system (blue) are shown for a better space orientation.</p

Mixing and clearance times.

a<p>Exp. experiment;</p><p>T_M mixing time;</p><p>T_C clearing time; min minutes.</p><p><i>In vivo</i> times of mixing and clearance in all five experiments simulating blood washout with head shaking (Exp. 1–5) and experiment with pulsatile flow without head shaking (Exp. 11)^a.</p

Repeatability of experiments.

<p>Standard deviation (n = 6) for normalized gray value and time to achieve a normalized gray value of Exp. 1 (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041677#pone-0041677-t001" target="_blank">Table 1</a>). The horizontal lines labeled with 100%, 50%, 25% and 12.5% represent the normalized gray values from a calibration experiment with according blood model concentrations.</p

Examples of washout images at different time steps.

<p>Five <i>in vivo</i> time step images of four dye washout experiments. Settings of experiments are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041677#pone-0041677-t001" target="_blank">Table 1</a>.</p

Experimental parameters.

a<p>CSF cerebrospinal fluid; Exp. experiment; α angle of the cistern model simulating head position; φ_max shaking angle amplitude;</p><p><i>f</i> shaking frequency; rpm revolutions per minute;</p>b<p><i>in vitro</i> time scale;</p>c<p><i>in vivo</i> time scale.</p><p>Eight experimental settings with a steady physiological net CSF flow rate, settings of both reference experiments (Exp. 9 and 10), and experimental setting for pulsatile CSF flow (Exp. 11). Note that during Exp. 9 (“CSF-washout”) no blood was injected and during Exp. 10 (“Blood-CSF-diffusion”) zero CSF flow was simulated.^a.</p

Model of the basal cistern.

<p>Surface of the reconstructed basal cistern in a lateral (A) and frontal (B) view. The g-arrow indicates the longitudinal axis of the human body which is aligned with the gravitational force for a sitting patient. Photo (C) shows the corresponding wax model and photo (D) the fabricated silicone model. Arrows indicate the sites of the inflow of the blood model as well as the inflow and outflow of the CSF model.</p

Cyclin A1 expression levels in FSHD and other myopathies (microarrays).

<p><i>CCNA1</i> Human Exon 1.0 ST Array signal levels in FSHD (n = 4), healthy controls (n = 7), CAV3 (n = 4), DYSF (n = 4) and FHL1 (n = 3).</p