cheerleader wrote:drsclafani wrote:
thanks, excellent
It surprises me that external veins like the condylar emissary vein would flow INTO the head.
since i have begun starting all procedures from the transverse sinuses, i have noted three patterns in patients with ccsvi
1. enormous condylar veins draining into the posterior neck muscles and the vertebral veins
2. completely nonvisualized condylar veins
3. small condylar veins
I have never seen a condylar vein drain into the brain
Trying to understand why some patients have very large and others have very small condylar and other emissary veins is perplexing.
perhaps prenatal jugular malformations result in large emissary canals.
perhaps jugular stenoses developing after skull development inhibits enlargement of bony canals. I find it implausible that emissary canals would enlarge much later in life.
Thanks for the links
Found some interesting research on condylar differences in 50 normals, as shown on CT scan. It seems that in normals, there is asymetry or ageneis in the condylar veins, but not these giant veins like you're seeing in pwMS, and the occipital bone showed differences which affected the veins...
In all cases, the anterior condylar veins connected the anterior condylar confluence to the marginal sinus; however, a number of cases with asymmetry and agenesis in the posterior and lateral condylar veins were seen. The posterior condylar vein connected the suboccipital cavernous sinus to the sigmoid sinus or anterior condylar confluence. The posterior condylar canal in the occipital bone showed some differences, which were accompanied by variations in the posterior condylar veins. In conclusion, there are some anatomical variations in the venous structures of the craniocervical junction; knowledge of these differences is important for the diagnosis and treatment of skull base diseases. Contrast-enhanced CT using a multidetector scanner is useful for evaluating venous structures in the craniocervical junction.
http://bjr.birjournals.org/cgi/content/ ... 83/994/831
Dr. Z found that the condylar system became one of the main collateral pathways activated in CCSVI. In fact, that's exactly what my hubby had. No jugulars, but big, squirrely condylars. Once he had jugular veins open and flowing, the condylars disappeared. Since his blockage was high, into transverse sinus, maybe that's why the condylars became developed? Maybe it has to do with the location of stenotic lesion and availability of collateral drainage at that location....the old freeway detour analogy?
The main collateral pathways activated in the course of CCSVI are the condylar venous system, the pterygoid plexus and the thyroid veins.2,6 Additionally, the suboccipital cavernous sinus and the hemiazygous-lumbar venous anastomosis with the left renal vein may also become prominent substitute circles. Collateral circulation prevents brain oedema and intracranial hypertension,2,4 and ensures a correct but slower, and thus insufficient, venous drainage.12,14
http://phleb.rsmjournals.com/content/25/6/269.full
anyway, just read that you may still be on vacation...in which case, nevermind, and we'll all catch up with you later....
cheer
Hi cheer.
i am back but not rested after visiting the mosel valley and the black forest and preoctoberfest munich
I think these condylar veins have some importance in clarification of the origins of CCSVI.
It is my understanding from some reading of reports of old anatomical dissections of cadaver skulls and brains that the condylar emissary vein is the most common one in humans. They connect the transverse sinus (sigmoid portion) inside the skull with posterior neck veins that enable them to communicate quite freely with the vertebral veins which are transmitted through the foramen magnum that lies adjacent to the posterior condylar canals. These canals occur in about 77%% of cadavers. They are bilateral in about 50%. Absence of BOTH is pretty uncommon. There is an experiment with passing wires of various sizes into the canals and the vast majority of these canals measured less than 2mm, although smaller occured in 10% and larger occured in only 15%.
This is not my experience in PwMS, who seem to have much larger veins in more than half (guesstimate).
The emissary veins develop in the embryo FIRST and as the fetus develops a skull LATER, bone surrounds these veins and nerves, thus creating the canal the vein passes through. This suggests that any enlargement of the emissary vein occurs before bone development is completed in early childhood. While it is common for high flow arteries (such as aneurysms and arteriovenous malformations), to enlarge the bony canal, i find it more difficult to imagine the bony canal enlarging as low pressure flow through a vein increases because of obstruction of the internal jugular veins.
Thus these findings on venography suggest that CCSVI (at least in cases with quite large condylar emissary veins) represents a congenital malformation of venous development.
