Our aim was to quantitatively evaluate the role of internal jugular venous reflux (IJVR) in transient global amnesia (TGA). Meta-analysis of case-control studies was conducted using Medline, Current contents connect, ISI Web of Knowledge, Biological abstracts and Scopus, plus citations of selected studies. We performed sensitivity and subgroup analyses to assess the effect of methods of IJVR determination, blinding of studies, and definition of IJVR on the results. Seven studies were included in the first meta-analysis which investigated the frequency of IJVR in 312 patients and 261 controls. IJVR was more common in patients (OR 5. 867, 95 % CI 3. 895-8. 838,). Meta-analysis of blinded studies did not alter our results (OR 10. 894, 95 % CI 5. 396-21. 996). Another meta-analysis with seven studies was performed in which, IJVR was more frequent in patients with TGA and precipitating factors compared with those without any identifiable precipitating factors (OR 2. 889, 95 % CI 1. 748-4. 777). IJVR is a risk factor for TGA. However, not all patients with history of TGA spells had IJVR and this, together with higher frequency of IJVR in patients with TGA who experienced precipitating events, showed the need of considering several other factors in further primary researches.
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