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The aim of the study was to compare hemodynamic parameters, the sequence of remodeling of the jugular and extrajugular outflow tracts of cerebral venous circulation in extrinsic stenosis and hypoplasia of the internal jugular vein (IJV). Material and methods . Groups with external compression and IJV stenosis (n = 50), with IJV hypoplasia (n = 27), and after IJV ligation/resection (n = 6) as a model of IJV occlusion with a minimal cerebral venous insufficiency and venous encephalopathy and control group (n = 31) were compared. All patients underwent a neurological examination, ultrasound duplex scanning of the IJV (J2 and at the level of stenosis), common carotid and vertebral artery (V2), 2DToF or 3DToF magnetic resonance venography of the neck veins. The degree of stenosis of the IJV, the crosssectional area and the time average blood flow velocity, the calculated indicator of the venous-arterial balance (VAB) were determined according to the modified formula. Results and discussion . In the group of external compression of the IJV, stenosis averaged 64.52 %. The area of the IJV at the site of stenosis was 6 times, and at the standard place (J2) – 3 times less than the area of the opposite IJV. The hypoplastic IJV throughout its entire length (from J1 to J3) had the same area (0.21 ± 0.12 cm 2 ), smooth contours, without local expansions or narrowings. A very low blood flow velocity (10.2 ± 11.67 cm/s) is characteristic for stenosis, in contrast to the normal velocity in the hypoplastic vein and in the control group. The blood flow velocity in the contralateral IJV with external stenosis does not differ from normal, but it is increased with hypoplasia (34.62 ± 12.23 cm/s). With MR venography, it is possible to detect a stenosing factor, symptoms of a filling defect, a decrease or loss of a blood flow signal, and an assessment of the overall picture of remodeling of the venous network of the neck. A decrease in the IJV area on the side of the lesion/anomaly corresponds to negative remodeling, while an expansion of the opposite IJV corresponds to positive remodeling. If the obstruction persists, the homolateral, then the contralateral external jugular vein expands, then the vertebral veins and plexuses, spinal epidural veins, anterior jugular and posterior cervical veins expand too. The magnitude of the IJV on the side of the anomaly/pathology with hypoplasia did not differ from the value with stenosis (9 %), but was slightly less than on the opposite IJV (53.39 ± 13.40 and 67.24 ± 18.02 %, respectively, p < 0.06) and significantly less compared to the control (24.16 ± 8.06 % on the left and 33.15 ± 8.27 % on the right, p < 0.0001), which makes this indicator a good additional criterion for outflow abnormality according to the IJV of one side.
Семенов et al. (Wed,) studied this question.