vertebral venous capacity limits
Posted: Wed Aug 03, 2011 12:13 pm
http://jap.physiology.org/content/94/5/1802.full
Maybe the vertebral venous drainage system is only capable of taking on a percentage of the jugular drainage, around 26% as seen here. So combined stenoses of up to 26% in the jugulars might be what the body can compensate for. As soon as our stenoses get beyond 26%, the body cannot compensate as well, although it tries. If the jugular stenoses get up to 80 to 100%, as mine did, it would seem that the vertebral venous system, however valiant, cannot compensate.
What do you think? I found this possibly informative.
The article does discuss the role of deep cervical veins and the intraspinal epidural system which the authors assume must be responsible for taking the remaining jugular flow (a rather large 50%) that has been dispersed.
Dr. Doepp of Germany happens to be an author on this study, from 2002.
If you compress the jugular veins when lying down, the vertebral veins will take on 19% of the jugular drainage capacity. Similarly, when upright, without any compressing, they take on 26% of the jugular drainage capacity.In contrast, nonjugular drainage patterns insubject 6 seem mainly to follow the VVs as fewer deep cervical veins could be visualized. Combined with a deeper location of the cervical veins, predominantly surrounding the splenius capiti muscles, circular neck compression probably did not result in any significant flow obstruction, explaining the absent VV flow rise. Overall, the additional cervical vein obstruction led to a further VV flow increase of 58 ± 53 ml/min (range: −10 to 140 ml/min), yielding VV flow values compensating 19% (one-fifth) of the jugular drainage capacity. A similar VV capacity of 26% (one-fourth of jugular venous flow) was seen within the upright body position (23).
Maybe the vertebral venous drainage system is only capable of taking on a percentage of the jugular drainage, around 26% as seen here. So combined stenoses of up to 26% in the jugulars might be what the body can compensate for. As soon as our stenoses get beyond 26%, the body cannot compensate as well, although it tries. If the jugular stenoses get up to 80 to 100%, as mine did, it would seem that the vertebral venous system, however valiant, cannot compensate.
What do you think? I found this possibly informative.
The article does discuss the role of deep cervical veins and the intraspinal epidural system which the authors assume must be responsible for taking the remaining jugular flow (a rather large 50%) that has been dispersed.
While I agree that these veins would play a role as well, how would we know if a percentage of this flow is not dispersed to different veins but instead the flow slows down due to the outflow obstruction? That they did not find anywhere near the total dispersed flow from the jugulars in the vertebral veins or the deep cervical veins could lend support to the outflow obstruction slows down the inflow theory, which would lend support to the idea of hypoxia playing a role in CCSVI.The only moderate further VV flow increase during circular neck compression (8% of total jugular flow) is probably due to a limited compression effect on deep cervical veins caused by their anatomic location (Fig. 2).
Dr. Doepp of Germany happens to be an author on this study, from 2002.