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Archived Comments for: Hypoperfusion of brain parenchyma is associated with the severity of chronic cerebrospinal venous insufficiency in patients with multiple sclerosis: a cross-sectional preliminary report

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  1. Doppler angle error

    Paul Shadrach, Providence Health & Services

    31 May 2011

    On figure 2 showing Doppler and US evidence of internal jugular venous obstruction the depiction of "blocked flow" in A is a complete misrepresentation of the correct application of Doppler approaches used to assess blood flow. The reason there is no color and no spectral signal is because the angle of incidence is 90 degrees. It does not demonstrate "blocked flow" at all.

    Competing interests


  2. Methodology for flow block detection

    Paolo Zamboni, University of Ferrara

    16 June 2011

    In a large number of cases, no flow can be detected within the internal jugular vein (IJV), which may suggest the presence of intraluminal defects, like the septum showed in fig.2 of our article. There are two main possibilities: i) flow is not detected because the IJV is almost completely collapsed and cannot be distended by a Valsalva maneuver; this is compatible with a hypoplasia. ii) flow is not detected but the lumen of the IJV is clearly visible. In this case, absence of flow in colour Doppler mode should be confirmed by Doppler spectral analysis and absence of thrombosis by compression. This is compatible with absent flow in a filled IJV, like in the case depicted in Fig. 2. Particularly, absence of flow was always diagnosed with a complete study which includes either sample volume placed in the centre of the vessel under examination with angle of insonation 45°-60°, or completely open through the entire lumen without any angle correction. We always used the lowest PRF value as well as steering angle correction in the longitudinal aspect. All these manoeuvres cannot be showed in just one figure, but all were included in our protocol. The International Society for Neurovascular Diseases is publishing a detailed Consensus document on the recommended protocol for ultrasound screening of CCSVI. This may overcome the lack of details on US protocols related to constrain of space of a research article. Finally, absence of flow needs to be confirmed in 2 postures to become a positive CCSVI parameter.

    Competing interests

    Esaote Biomedica, donated equipments to the Vascular Diseases Center of the University of Ferrara, Italy