Biomedical Engineering Reference
In-Depth Information
Fig. 22.5
(
Left
): Sagittal view of a
z
-slice of the mildly obstructed aqueduct of Sylvius. The con-
tour lines denote velocity magnitude. (
Centre
): Lines tangent to the instantaneous velocity vector
(at an instant coinciding with peak systole) in the aqueduct of Sylvius, indicating a smooth flow.
(
Right
): Rotated view of lines tangent to the instantaneous velocity vector (at an instant coinciding
with peak systole) in the aqueduct of Sylvius and fourth ventricle (open case)
displays the lowest peak velocities of all the outlets (did not exceed 0.02 m
/
s)
throughout the different applied occlusions. From an anatomical perspective, this
canal acts as a cushioning system for the spinal cord. This is in good agreement
with similar inferences made in the literature (Loth et al.,
2001
; Gupta et al.,
2009
,
2010
).
A final note is made on the complexity of the flow. The streamlines in Fig.
22.5
(right) show just how complicated and asymmetric the flow within the ventricular
system is (namely in the fourth ventricle). Here, two vortices have developed, and
they both rotate in an anti-clockwise direction. The other portion of CSF travels
along the floor of the fourth ventricle and leaves via the three foramina. In the same
figure, one can also appreciate how flow exits through the foramen of Magendie
and in addition how a negligible amount leaves through the central canal. These
visualizations of the cranio-caudal flow are in good agreement with the literature
(Stadlbauer et al.,
2010
).
22.5 Future Work
The current MPET model can be extended to include a more varied range of hy-
drocephalic cases, namely those associated with atresia of the three foramina in
the fourth ventricle and both the foramina of Monro, see Fig.
22.2
. The effects of
shunting, endoscopic third ventriculostomy (ETV) and a very recent development
in fourth ventriculostomy (Giannetti et al.,
2011
) will be investigated. This investi-
gation will be done in conjunction with the above cases of aqueductal stenosis, or
