|Criterion||Definition according to ‘Zamboni protocol’*||No of MS patients||No of controls||p Value†|
|1||Reflux >0.88 s in the IJVs and/or VVs in sitting or supine position||0||0||/|
|2||Reflux >0.5 s in the deep cerebral veins||0||0||/|
|3||High resolution B-mode evidence of IJV stenoses defined as VCSA of ≤0.3 cm† ‡||13||16||0.48|
|4||Flow not Doppler-detectable in at least one IJV or VV§ in the supine and upright position||0||1§||1.0|
|5||Atypical main cerebral venous outflow measured in IJV defined as ΔVCSAupright–supine>0¶||0||0||/|
|At least two criteria fulfilled||0||1||1.0|
↵† Fisher exact test.
↵‡ Criterion 3 was not defined consistently by Zamboni et al. We used the definition in Zamboni et al,5 where a venous cross-sectional area (VCSA) of ≤0.3 cm2 is given as a cut-off value. Doepp et al21 obtained different results in assessing criterion 3, but referred to a deviating definition of ‘stenosis’ given in Zamboni et al,25a J Neurol Sci 2009;282:21–7, where a local VCSA reduction of ≥50% is considered ‘stenotic.’
↵§ Criterion 4 is not specified clearly by Zamboni et al. Here, we defined criterion 4 as ‘no flow detectable in at least one internal jugular vein (IJV) or vertebral vein (VV) in the supine and the upright position.’
↵¶ This Zamboni criterion was modified. Given that negative values for ΔVCSA in the IJV represent not a pathological but a physiological state, this criterion was substituted by ‘atypical flow,’ /, indicates p value could not be calculated. indicating a positive value of ΔVCSA.