There are currently several centres actively promoting and performing balloon dilatation, with or without stenting, for CCSVI. However, it must be stated that no randomised trial data are available to back the theory behind the treatment or to support its use. There are also no RCTs currently in progress. Therefore, the basis for this treatment rests on anecdotal evidence and successful testimonies by patients. It is for these reasons that CIRSE feels that this is not a sound basis to currently offer this new treatment, which has not yet been part of a RCT.
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The core of this new theory is the CCSVI syndrome, or the abnormal venous drainage from the brain. However, venous drainage from the head has an impressive anatomic variation, which is not very well catalogued in most textbooks. Also valves can be present at a variety of sites in the head and neck veins. Interventional Radiologists who practise para-thyroid sampling are well aware of the huge variety in venous anatomy. Besides the huge variation in normal venous anatomy the jugular veins have some natural narrowing at two sites and the azygous vein, prominent in the CCSVI theory, does not drain the brain at all. The azygous can clearly drain the spinal cord but not solely, as there are many intercostal venous collaterals which fulfil the same function. In addition, the fact that this imaging is done in the supine position will have a great influence on blood flow and image interpretation. There have recently been randomised studies comparing socalled venous stenoses in patients with and without MS (3-4). Both studies show that there is no difference in the prevalence of venous stenoses between the two groups. This seems to be a very strong argument against the existence of CCSVI. However, physicians performing CCSVI treatment point out that these studies were not performed according to the specific Venous Hemodynamic Insufficiency Severity Score (VHISS) criteria. The other part of the theory is that the venous outflow obstruction needs to be treated. However, if there is a real haemodynamic venous outflow obstruction, there should also be a pressure gradient and this gradient should disappear after successful balloon dilatation. It has been shown, and confirmed by those who perform balloon dilatation for CCSVI, that over the so-called stenosis there is never a measurable pressure gradient. Those who perform this treatment argue that it is not the pressure gradient but the change in outflow pattern, caused by this stenosis, that is the pathological entity.