Abstract
Abnormal extracranial venous drainage modality has been considered an etiology of transient global amnesia (TGA). Evidence suggests that the transmission of the intrathoracic/intraabdominal pressure during a Valsalva maneuver (VM) is mainly through the vertebral venous system, and patency of internal jugular vein (IJV) is essential for venous drainage and pressure releasing. We hypothesize that obstruction of IJV venous drainage is a contributing factor in TGA pathogenesis. A magnetic resonance (MR) imaging protocol was used in 45 TGA patients and 45 age- and sex-matched controls to assess the morphologies of IJV, brachiocephalic vein (BCV) and asymmetry of transverse sinus (TS). The IJV was divided into the upper- and middle-IJV segments. Compared to the controls, TGA patients had significantly higher rates of moderate and severe compression/stenosis at the bilateral upper-IJV segment (left: 37.8% vs. 17.8%, P = 0.0393; right: 57.8% vs.15.6%, P<0.0012), in left BCV (60% vs. 8.9%, P<0.0004), and in TS hypoplasia (53.3%% vs. 31.1%, P = 0.0405). The prevalence of at least one site of venous compression/stenosis in IJV or BCV was significantly higher in patients than in controls (91.1% vs. 33.3%, P<0.0004). The diameter of the left TS in MRV, but not in T1 contrast imaging, was significantly smaller in TGA patients than in controls (0.31±0.21 vs. 0.41±0.19, P = 0.0290), which was compatible with downstream venous stenosis/obstruction. TGA patients have a higher prevalence of compression/stenosis of the bilateral IJV and the left BCV and TS hypoplasia, which is new evidence that supports the role of extracranial veins in TGA pathogenesis.
Highlights
Transient global amnesia (TGA) is defined as a sudden and transient inability to acquire new information [1]
Cerebral venous congestion/hypertension has been considered a cause of TGA, which was attributed to venous reflux during a Valsalva maneuver (VM) consequent to valve incompetence of the internal jugular vein (IJVVI) [4,5,6]
In comparison with the controls, there was significantly more moderate or severe IJV compression/stenosis in TGA patients at the bilateral upper-IJV level, while there was no difference at the middle-IJV level
Summary
Transient global amnesia (TGA) is defined as a sudden and transient inability to acquire new information [1]. Cerebral venous congestion/hypertension has been considered a cause of TGA, which was attributed to venous reflux during a Valsalva maneuver (VM) consequent to valve incompetence of the internal jugular vein (IJVVI) [4,5,6] Based on this theory, the deep cerebral veins draining the hippocampus are greatly suspected to be involved in TGA, and the hemodynamic changes of cerebral venous flow in these drainage veins can be shown at least during VM. We postulated that there are BVO obstructions [16,17,18] in TGA patients, which may weaken the protective mechanism to relieve intracranial venous pressure during VM and induce constriction of intracranial major artery. We used an MR-imaging protocol [18,19,20,21,22] in this study to investigate the BVO pathway obstruction in TGA patients
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