Wow! Read this!

[BooBear]

http://www.springerlink.com/content/6f7mbd91y3kdl1na/

Because of their anastomotic interconnections, only simultaneous obstruction of veins of Galen and basal veins wil effectively obstruct deep venous outflow. This can occur in the tentorial incisura, from swelling or displacement of the midbrain due to brain oedema, haematoma or tumour. Complete obstruction of great vein of Galen and basal veins leads to rapid death. In patients who survive incomplete obstruction, various combinations of damage to parts of the deep venous territory exist. This is possible because very many tributaries of the deep system unite below and sometimes above the tentorial incisura. The hallmarks these varying deep venous obstructions have in common are sparing of the subcortical white matter of the convexity, and cortical involvement limited to the limbic lobe and visual cortex. Obstruction of cerebral venous outflow explains many pathological phenomena. Treatment must aim at relieving this obstacle to blood flow.

[frodo]

Can you explain it a little?

[BooBear]

Here is what I think we can take (simply) from the article:

- Collateral veins can substitute for outflow in lieu of typical outflow to the great vein of Galen (supports the collateral veins seen in CCSVI);

- Simultaneous obstruction of both the great vein of Galen and the basal veins will result in serious injury (and even death); however, some obstruction can be survived...with damage in a variety of pathological forms (supports MS as a potential byproduct of blood flow obstruction).