Fulfillment of the five ‘Zamboni criteria’ in 20 MS patients and 20 healthy controls
| 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.