{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,26]],"date-time":"2026-07-26T05:48:18Z","timestamp":1785044898713,"version":"3.55.0"},"reference-count":38,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2020,12,16]],"date-time":"2020-12-16T00:00:00Z","timestamp":1608076800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Neurol."],"abstract":"<jats:p><jats:bold>Background:<\/jats:bold> Vasovagal syncope (VVS) occurs due to cerebral hypoperfusion from a fall in blood pressure, with accompanying bradycardia in most cases. Seizure and\/or asystole may accompany VVS, though their prediction within the VVS cohort remains elusive.<\/jats:p><jats:p><jats:bold>Objective:<\/jats:bold> To further characterize VVS and to find predictive features of \u201ccomplex\u201d VVS (defined as VVS associated with seizures and\/or asystole).<\/jats:p><jats:p><jats:bold>Methods:<\/jats:bold> We reviewed medical records of all patients who were referred for orthostatic intolerance and had a definite VVS during the head-up tilt table testing (HUTT). The following variables were recorded: cardiovascular indices during HUTT, autonomic testing results, and semiology of asystole and\/or seizure when present. Simple frequency and correlation analysis were performed using the ANOVA.<\/jats:p><jats:p><jats:bold>Results:<\/jats:bold> A total of 78 independent VVS were recorded in 60 patients of which 24% were not preceded by presyncope. Vasodepressor (45%) and mixed (38%) VVS were the most prevalent types. Eighteen (23%) were complex VVS; five had an associated seizure (SySz), nine were accompanied by asystole (SyAs), and four had both (SySzAs). Males were significantly more likely to have complex VVS. Mean asystole duration was somewhat longer in the SyAsSz group. The severity of bradycardia significantly correlated with complex VVS and was a predictor of SySz. Autonomic abnormalities were frequent but did not distinguish the two VVS subgroups. Seizures had multiple distinguishing features from those typically associated with epileptic seizures.<\/jats:p><jats:p><jats:bold>Conclusions:<\/jats:bold> The underlying pathophysiologic mechanisms of complex VVS remain unclear, but the severity of cerebral hypoperfusion due to bradycardia likely plays a key role in seizure generation.<\/jats:p>","DOI":"10.3389\/fneur.2020.550982","type":"journal-article","created":{"date-parts":[[2021,1,10]],"date-time":"2021-01-10T11:08:17Z","timestamp":1610276897000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":5,"title":["\u201cComplex\u201d Vasovagal Syncope: A Zebra Among Horses"],"prefix":"10.3389","volume":"11","author":[{"given":"Anwer Zohaib","family":"Siddiqi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Derrick","family":"Blackmore","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zaeem Azfer","family":"Siddiqi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2020,12,16]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"69","DOI":"10.1007\/s10286-011-0119-5","article-title":"Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome","volume":"21","author":"Freeman","year":"2011","journal-title":"Clin Auton Res."},{"key":"B2","doi-asserted-by":"publisher","first-page":"725","DOI":"10.1586\/14779072.2016.1164034","article-title":"Evaluation of syncope: focus on diagnosis and treatment of neurally mediated syncope","volume":"14","author":"Lee","year":"2016","journal-title":"Expert Rev Cardiovasc Ther."},{"key":"B3","doi-asserted-by":"publisher","first-page":"1883","DOI":"10.5603\/KP.2018.0161","article-title":"ESC guidelines for the diagnosis and management of syncope","volume":"39","author":"Brignole","year":"2018","journal-title":"Eur Heart J."},{"key":"B4","doi-asserted-by":"publisher","first-page":"471","DOI":"10.3389\/fphys.2014.00471","article-title":"Syncope: epidemiology, etiology, and prognosis","volume":"5","author":"da Silva","year":"2014","journal-title":"Front Physiol."},{"key":"B5","doi-asserted-by":"publisher","first-page":"126","DOI":"10.1007\/s10286-005-0244-0","article-title":"Vasovagal syncope darwinian fitness","volume":"15","author":"Diehl","year":"2005","journal-title":"Clin Auton Res."},{"key":"B6","doi-asserted-by":"publisher","first-page":"1088","DOI":"10.1111\/jce.13266","article-title":"Pathophysiology of reflex syncope: a review","volume":"28","author":"Adkisson","year":"2017","journal-title":"J Cardiovasc Electrophysiol."},{"key":"B7","doi-asserted-by":"publisher","first-page":"11","DOI":"10.1152\/ajplegacy.1945.143.1.11","article-title":"A study of orthostatic insufficiency by the tiltboard method","volume":"143","author":"Allen","year":"1945","journal-title":"Am J Physiol Content."},{"key":"B8","first-page":"372","article-title":"The fainting patient: value of the head-upright tilt-table test in adult patients with orthostatic intolerance","volume":"164","author":"Lamarre-Clich\u00e9","year":"2001","journal-title":"CMAJ."},{"key":"B9","doi-asserted-by":"publisher","first-page":"e49","DOI":"10.1016\/j.ijcard.2013.08.114","article-title":"Head-up tilt testing for diagnosing vasovagal syncope: a meta-analysis","volume":"169","author":"Forleo","year":"2013","journal-title":"Int J Cardiol."},{"key":"B10","doi-asserted-by":"publisher","first-page":"277","DOI":"10.4330\/wjc.v8.i3.277","article-title":"Tilt table test today - 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