A study in 268 MS patients and 155 controls reported more a frequency of CCSVI in the MS group that was more than twice as high as in the controls group and was also higher in the progressive MS group than in the non-progressive MS group. This study found no relationship between CCSVI and HLA DRB1*1501, a genetic variation that has been consistently linked to MS. Diagnosis
CCSVI was first described using specialized extracranial and transcranial doppler sonography. Five ultrasound criteria of venous drainage have been proposed to be characteristic of the syndrome, although two are considered sufficient for diagnosis of CCSVI:
reflux in the internal jugular and vertebral veins,
reflux in the deep cerebral veins,
high-resolution B-mode ultrasound evidence of stenosis of the internal jugular vein,
absence of flow in the internal jugular or vertebral veins on Doppler ultrasound, and
reverted postural control of the main cerebral venous outflow pathways.It is still not clear whether magnetic resonance venography, venous angiography, or Doppler sonography should be considered the gold standard for the diagnosis of CCSVI. Use of magnetic resonance venography for the diagnosis of CCSVI in MS patients has been proposed by some to have limited value, and should be used only in combination with other techniques. Others have stated that magnetic resonance venography is a valid measure which has advantages over Doppler including the fact that results are more operator-independent.Diagnostic criteria have been criticized. Both the number of criteria and the need of being positive for two of them as enough for diagnosis are arbitrary ideas.
Organizations
Several national and international organizations have been created to further the research and dissemination of the CCSVI theory, such as the International Society for Neurovascular Disease and the National CCSVI Society of Canada. They are working together with already existing organizations like the International Union of Phlebology (Union internationale de phlébologie-UIP- in French, its original working language) of which Zamboni is a member. The UIP for example proposed that developmental abnormalities were the primary cause of CCSVI. Research
There were further studies aimed at clarifying if there is a relationship between MS and CCSVI. In particular, the US and Canadian MS societies launched seven such studies. Recent reviewers have shown "no significant difference in prevalence of CCSVI in people with MS compared to people without MS". In 2014 imaging criteria for venous abnormalities were published to help with research on this topic. See also
Chronic venous insufficiency
Pathophysiology of multiple sclerosis
Vascular myelopathy

References
Further reading


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