Diagnostic IVUS: findings Normal Internal Jugular vein (Figure 1)
The IJVs are the primary venous outlets for the cerebral blood volume when a human is supine. The vertebral veins and the vertebral plexus assume this function in the erect position. The sigmoid sinus, the terminal component of the transverse sinus, combines with the inferior petrosal sinus to form the superior jugular bulb. The vein runs a continuous course down the neck in the lateral aspect of the carotid sheath where it dilates (inferior bulb) before enter the innominate vein at its confluens with the subclavian vein. Valves, usually biscuspid, are located near the confluens are present in about 85% of humans and. There may be more than one set of valves. Major branches of the IJV include the inferior petrosal sinus, pharyngeal vein, the common facial vein, the lingual vein, and superior and middle thyroid veins. In CCSVI IJV outflow is compromised
On IVUS, the IJV varies in its appearance depending upon location in the neck. The upper segment (J3) starts as a larger structure (superior jugular bulb) that quickly diminishes in circumference. It occasionally flattens as it courses over the second cervical vertebra before expanding in diameter in the mid portion of the neck (J2). Often tributaries are seen in this region. A second crescentic indentation, representing the compression by the carotid artery, may be seen in this region. The lower jugular vein is normally dilated as it joins the subclavian vein (inferior bulb).
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