The findings were published on 3 October in the Canadian Medical Association Journal.
The team reviewed several hundred peer-reviewed publications on CCSVI and MS and found that eight met the team’s criteria for inclusion in the meta-analysis – the studies presented original data, used Doppler ultrasonography and assessed both people with MS and a control group of either healthy individuals or those with other neurological disorders. Studies by Zamboni, Zivadinov, Mayer, Krogias, Doepp, Centonze, Baracchini and Al-Omari were included in the analysis.
The findings showed a statistically significant association between CCSVI and MS. They stress that this association does not indicate whether CCSVI may be a cause or a consequence of the condition. There was, however, no statistical difference in the prevalence of CCSVI between people with MS and people with other neurological disorders.
The authors express concern at the wide variability in the studies as shown by their statistical analysis. They discuss the possible reasons for this including the difficulty of assessing one of the parameters - reflux in deep cerebral veins, and the reproducibility between ultrasonographers or with repeat assessments by the same ultrasonographer.
The authors are also particularly concerned by the poor reporting of the success of blinding in the studies. Blinded studies, in which the health professional conducting the assessment does not know whether an individual is a healthy control or a patient, removes any potential bias in the assessment.
The authors conclude that "Further high-quality studies, using identical ultrasound protocols, are needed to definitively determine whether chronic cerebrospinal venous insufficiency is more frequent among patients with multiple sclerosis than among those without it."
The full article can be found here
