The execution of the Valsalva maneuver and its effects on volume and blood

flow are well codified, also in mathematical models, both in supine and standing position, and both in the jugular and vertebral axis [10]. Fig. S1 shows the consequences of Valsalva maneuver also at middle (J2) and distal (J3) IJV segments of the IJV. But, why perform the Valsalva maneuver also in J2–J3 segments? The existence of a «truncular» jugular insufficiency is documented in patients with transient global AZD2281 research buy amnesia with ultrasound techniques and the retrograde extent of this venous reflux into the sygmoid sinus has been found in this subgroup of patients by MRI [11], [12] and [13]. The main pitfall of this criterion is that Zamboni et al. [1] and [2] derived the threshold of >0.5 s from phlebological studies in CVI where it serves to quantify venous valve insufficiency following deflation of a tourniquet. Moreover the identification of the so-called intracranial reflux was performed by using a not validated window. In this study the known and validated temporal bone window will be used and in the advanced protocol also the TS is insonated, ipsi- or controlaterally. The BVR is a virtually constant vein and it is very difficult to have abnormal flow LY294002 research buy patterns in it as a localized disease, outside cerebral vein thrombosis, particularly thrombosis of the SRS. The TS is characterized by a higher variability and it can be considered

as a direct continuation to the IJV axis. Fig. S2 shows an abnormal flow direction in the Doppler waveform of the transverse sinus,

as incidental finding in an asymptomatic subject. The main pitfalls of this criterion is that it was not defined consistently by Zamboni et al., because there are at least two different definition used in different papers: – ΔCSA of <0.3 cm2[1] The first published studies of Zamboni et al. cited the paper of Lichtenstein et al. [14] as reference for the ultrasound diagnostic threshold of IJV stenosis, but the aim of the study was to assess the asymmetry of Sclareol size of IJVs for selecting the best side to central venous catheterization, in 80 patients from Intensive Care Unit. Furthermore the asymmetry does not mean stenosis and the selected CSA for making the catheterization difficult is 0.4 cm2. Moreover in angiographic studies of Zamboni et al. [15] there is not a pressure gradient across the venous stenosis. In this protocol the threshold of CSA < 0.3 cm2 was selected, coupled by a documentation of velocity parameters from a Doppler waveform. In Fig. 2 there is an example of a positive criterion 3, but with a doubtful differential diagnosis between a so-called “stenosis” and a more physiological IJV hypoplasia. Fig. 3 shows an ultrasound example of a real stenosis of the IJV at the valve level, in comparison with the MR venography of the same asymptomatic patient. The main pitfalls of this criterion derive from a general and nonspecific definition of this criterion.