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Table 2 Classification for the extracranial hemodynamic/functional venous abnormalities

From: Potential involvement of the extracranial venous system in central nervous system disorders and aging

Types[22, 24, 25, 27, 29, 40, 47, 48, 64, 90, 91, 98, 101, 110, 112, 114, 116, 118, 119] Definition
Venous reflux/bidirectional flow:  
Valsalva maneuver induced jugular venous reflux: • Valsalva maneuver-like activities which increase intrathoracic pressure may lead to IJV incompetence, known as jugular vein reflux and measured on DS or IVUS.
*Spontaneous venous reflux: • Present on DS examination in the IJV and vertebral veins and for more than 0.88 seconds with the head at 90° and 0°; delayed emptying time on CV.
*Venous reflux in the intracerebral veins: • Reflux/bidirectional flow on DS in the deep cerebral veins is defined as reverse flow for a duration of 0.5 s in one of the intra-cranial veins.
Abnormal venous flow distribution in extracranial veins: • Measurement of blood flow, blood volume and blood velocity by using DS, MR phase contrast imaging, CV or IVUS.
No flow in extracranial veins: • No flow on DS or IVUS or contrast noted in the vein on CV and MRV, despite deep breaths.
Abnormal posture control of IJV flow: • A negative ∆CSA on DS represents the loss of the normal postural control; altered estimation of changes in venous capacitance and venous resistance by posture change on plethysmography.
  1. Legend: CSA. cross sectional area; CV, catheter venography; DS, Doppler sonography; IJV, internal jugular vein; IVUS, intravascular ultrasound; MRV, magnetic resonance venography.
  2. *The controversy regarding the methodological validity of these quantitative definitions for spontaneous and intracerebral venous reflux included recent position statements from the ISNVD [97], the European Society of Neurosonology and Cerebral Hemodynamics (ESNCH) [132] and review studies [7] that expressed considerable concerns regarding the accuracy of the proposed criterion.