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How do stenosis at jugular cause focal lesions deep in brain

Posted: Tue Dec 14, 2010 9:01 am
by fogdweller
I was trying to figure out the mechanism for how a stenosis at the jugular level, sometimes well down the vein, could cause a focal lesions deep in the brain. Reflux could break down the blood brain barrier, but that would release cells into the brain in general, but how would the venocentric plaque form way down the vascular line?

Does Zamboni explain this somewhere? I do not recall seeing it.

Any ideas?

Posted: Tue Dec 14, 2010 2:57 pm
by AMcG
This is something which interests me too. Zamboni has not made it clear and I do not think the aetiology has been explained elsewhere either. I do have some ideas of my own based on basic cranial anatomy and the videos of my own jugulars. But of course I am not a doctor so please feel free to criticise/ignore.

First the ‘error condition’ when it happens is when you are lying on your back/side, resting or sleeping. This is when your jugulars are in use. Your body is relaxed and heart rate/breathing are low/slow. Both the thoracic pump and vascular pressure are at their lowest. Your whole system is ‘idling.’ So drainage from the brain will be at its slowest.

The veins draining your thalamus/hypothalamus (deep cerebral veins) drain to the back of your head thru the straight sinus and then curve round thru the two lateral and sigmoid sinus’ behind your ears to join the top of your jugulars. If you are lying on your back then the back of your head could be the lowest point of your body (depends what pillows you use). Lying on your side would raise the back of your head but lower one transverse sinus. So gravity is not going to help much in this situation either. In fact there could be substantial ‘up-hill’ flow required to get to the jugulars from some parts of the brain. This system sounds to me to be at it’s most precarious in this condition. Almost the only thing driving it is the pressure of the blood exiting the capillaries in the brain which is ‘pulsatile’ (it’s being switched on and off and on again...) There will be a natural tendency for blood to ‘pool/linger’ at the back of your head. Also the deep cerebral veins are known to have slow flow and are susceptible to reverse-flow in this situation. Slowed flow thru your jugulars would tend to make this situation worse.

The second factor is something I noticed in the little videos of my veins they made in Poland. In my left vein when they inject the die, most of the die disappears downwards quite quickly (normal flow) but some lingers on one side of the vein and slowly floats back up and disappears behind my jaw. My interpretation of this is that there is forward flow in the centre of the vein but slow backwards flow near the wall of the vein. Normal blood flow is faster in the centre of the vein and slower near the wall. Constrictions clearly would increase resistance along the walls of the vein – maybe enough to separate the two flows. That is what it looks like to me anyway. If that back-flow gets to the top of my jugular it would be down-hill back to the bottom of the straight sinus. Congestion in the straight sinus then slows outflow from the DCVs. Because the DCVs are sluggish anyway making that worse produces stasis or local hypertension.

Sounds plausible to me. Any other ideas?

Posted: Tue Dec 14, 2010 4:46 pm
by HappyPoet
Hi AMcG,

Dr. Flanagan discusses in his thread CCSVI and CCVBP much of what you said in your post. He says, "If you want to empty a bucket, you don't put the hole in the high end." I'm sure he'd like to discuss your ideas, so I urge you to drop him a post (or a PM).

Posted: Tue Dec 14, 2010 5:21 pm
by fogdweller
Thanks for the reply, AMcG. All of what you say makes sense, so maybe the focal plaque formation is a bit random. The weakness in the vessel wall appens most significantly farther upstream, and that is where the breakdown of the BBB leads to formation of a plaque. I have not really incorporated the deposit of iron into my thinking. I am still thinking along the inflamation/immune response eitology, and that may not be accurate.

Posibly the vessel wall is strongest downstream, so it is most likely to be damaged farther upstream, i.e. deeper in the brain.

I am not a doctor, either, but it is fun to try to think this stuff through. Plus, it is not as though the doctors have figured out what causes MS yet either, and they have been working at it over a hundred years.

Posted: Tue Dec 14, 2010 9:06 pm
by eric593
Thanks, AMcG, that summary of venous drainage was very helpful to me!