Prognostic value of early EEG abnormalities in severe stroke patients requiring mechanical ventilation: a pre-planned analysis of the SPICE prospective multicenter study
Authors: Benghanem Sarah , Kubis Nathalie , Gayat Etienne , Loiodice Ambre , Pruvost-Robieux Estelle , Sharshar Tarek , Foucrier Arnaud , Figueiredo Samy , Bouilleret Viviane , De Montmollin Etienne , Bagate François , Lefaucheur Jean-Pascal , Guidet Bertrand , Appartis Emmanuelle , Cariou Alain , Varnet Olivier , Jost Paul Henri , Megarbane Bruno , Degos Vincent , Le Guennec Loic , Naccache Lionel , Legriel Stephane , Woimant France , Gregoire Charles , Cortier David , Crassard Isabelle , Timsit Jean-François , Mazighi Mikael , Sonneville Romain ,   and the SPICE investigators, Ader Tiare , Barré Eric , Bout Hélène , Boursin Perrine , Bodiguel Eric , Bresson Damien , Salem Omar Ben Hadj , Combes Alain , Chrisment Anne , Collet Magalie , Duranteau Jacque , Crozier Sophie , da Silva Daniel , Demoule Amexandre , Decavele Maxens , Delpierre Eric , Diehl Jean Luc , Dres Martin , Faugeras Frédéric , Fournier Marie-Céline , Gauss Tobias , Gernez Coralie , Geri Guillaume , Hurel Dominique , Jamme Matthieu , Josse Laurence , Jurcisin Igor , Kerhuel Lionel , Lamy Catherine , Lamara Fariza , Lancelot Aymeric , Lapergue Bertrand , Lenclud Christophe , Lermuzeaux Mathilde , Magalhaes Eric , Mariotte Eric , Malissin Isabelle , Maldjian Alain , Marin Nathalie , Martin Jérôme , Martinez Thibault , Dessap Armand Mekontso , Monchi Mehran , Naim Giulia , Outin Hervé , Osman David , Papin Gregory , Pasquier Pierre , Pichereau Claire , Pissot Matthieu , Razazi Keyvan , Reuter Danielle , Richard Christian , Ruckly Stephane , Roux Damien , Schimpf Caroline , Staiquly Quentin , Servan Jérôme , Tanaka Sebastien , Thion Laurie-Anne , Toumert Karim , Traki Widad , Tran Marc , Vassel Philippe , Vigué Bernard , Zafimahazo Daniel , Zarka Jonathan 
Published: May 2024

Abstract
Introduction
Prognostication of outcome in severe stroke patients necessitating invasive mechanical ventilation poses significant challenges. The objective of this study was to assess the prognostic significance and prevalence of early electroencephalogram (EEG) abnormalities in adult stroke patients receiving mechanical ventilation.

Methods
This study is a pre-planned ancillary investigation within the prospective multicenter SPICE cohort study (2017–2019), conducted in 33 intensive care units (ICUs) in the Paris area, France. We included adult stroke patients requiring invasive mechanical ventilation, who underwent at least one intermittent EEG examination during their ICU stay. The primary endpoint was the functional neurological outcome at one year, determined using the modified Rankin scale (mRS), and dichotomized as unfavorable (mRS 4–6, indicating severe disability or death) or favorable (mRS 0–3). Multivariable regression analyses were employed to identify EEG abnormalities associated with functional outcomes.

Results
Of the 364 patients enrolled in the SPICE study, 153 patients (49 ischemic strokes, 52 intracranial hemorrhages, and 52 subarachnoid hemorrhages) underwent at least one EEG at a median time of 4 (interquartile range 2–7) days post-stroke. Rates of diffuse slowing (70% vs. 63%, p = 0.37), focal slowing (38% vs. 32%, p = 0.15), periodic discharges (2.3% vs. 3.7%, p = 0.9), and electrographic seizures (4.5% vs. 3.7%, p = 0.4) were comparable between patients with unfavorable and favorable outcomes. Following adjustment for potential confounders, an unreactive EEG background to auditory and pain stimulations (OR 6.02, 95% CI 2.27–15.99) was independently associated with unfavorable outcomes. An unreactive EEG predicted unfavorable outcome with a specificity of 48% (95% CI 40–56), sensitivity of 79% (95% CI 72–85), and positive predictive value (PPV) of 74% (95% CI 67–81). Conversely, a benign EEG (defined as continuous and reactive background activity without seizure, periodic discharges, triphasic waves, or burst suppression) predicted favorable outcome with a specificity of 89% (95% CI 84–94), and a sensitivity of 37% (95% CI 30–45).

Conclusion
The absence of EEG reactivity independently predicts unfavorable outcomes at one year in severe stroke patients requiring mechanical ventilation in the ICU, although its prognostic value remains limited. Conversely, a benign EEG pattern was associated with a favorable outcome.