Usefulness of head-up tilt test combined with video electroencephalogram to investigate recurrent unexplained atypical transient loss of consciousness

Convulsive syncope and epileptic seizure share many similar clinical features. Early diagnosis is critical for choosing the appropriate management strategy. Our aim was to evaluate the diagnostic yield of an innovative diagnostic strategy — combined head-up tilt test (HUT)/video electroencephalogram (EEG) monitoring — in patients with unexplained seizure-like transient loss of consciousness (T-LOC). Combined HUT/video EEG was performed in patients with unexplained atypical T-LOC with both syncope and seizure characteristics remaining undiagnosed after a first-line investigation. T-LOC diagnosis was achieved in case of reproduction of usual symptoms. Events were classified as vasovagal, psychogenic or epilepsy. The link between EEG abnormalities and T-LOC was determined by an epilepsy specialist. Clinical follow-up was performed to assess T-LOC recurrence. Hundred and one consecutive patients were prospectively enrolled (median age 26 [19; 46] years; 72% female) and underwent combined HUT/video EEG between 2007 and 2015. Antiepileptic drugs were being prescribed in 42% of patients. Combined HUT/video EEG was diagnostic in 67% of patients, leading to diagnosis of vasovagal syncope in 59 patients and psychogenic pseudosyncope in nine cases. Antiepileptic drugs were discontinued in 18 patients without epilepsy. Independent predictors of a definitive diagnosis were the presence of prodromal symptoms (odds ratio 5.97, 95% confidence interval 1.37–26; P=0.017) and a history of myoclonic jerks during T-LOC (odds ratio 4.36, 95% confidence interval 1.71–11.15; P=0.002). Combined HUT/video EEG is useful for investigating recurrent unexplained atypical seizure-like T-LOC, especially in patients with a history of myoclonic jerks or with documented interictal non-specific EEG abnormalities. Les syncopes convulsivantes et les crises d’épilepsies sont des évènements cliniques présentant des caractéristiques cliniques communes pouvant aboutir à un diagnostic erroné en pratique courante. Le but de cette étude est d’évaluer la valeur diagnostique du tilt test couplé à l’électroencéphalogramme sur une cohorte de patients présentant des pertes de connaissance transitoires atypiques inexpliquées récidivantes. Un tilt test couplé à un électroencéphalogramme a été réalisé sur une cohorte de patients présentant des pertes de connaissances atypiques, récidivantes, et inexpliquées malgré une 1re ligne d’investigation. Le diagnostic était retenu en cas de reproduction de la symptoma