Clinical PaperPrognostic value of electrographic postanoxic status epilepticus in comatose cardiac-arrest survivors in the therapeutic hypothermia era☆
Introduction
Recent guidelines issued by the American Academy of Neurology identify five factors invariably associated with a poor outcome of cardiac arrest survivors, namely, myoclonus on day 1; bilateral absence of the N20 component on somatosensory evoked potentials following median-nerve stimulation on days 1–3; serum neuron-specific enolase levels >33 μg/L on days 1–3; absence of pupillary or corneal reflexes; and extensor or absent motor response to pain stimuli on day 3 [1].
However these guidelines may have been changed by the introduction of therapeutic hypothermia and would need a reappraisal 2, 3, 4, 5, 6, 7, 8, 9. The American Heart Association and the European Resuscitation Council have taken into account this parameter in their Guidelines of Resuscitation 2010. It is now recommended to apply a minimum of 72 h of observation after restoration of spontaneous circulation and to systematically associate two prognostic parameters at least before predicting poor outcome in comatose survivors after cardiac arrest treated with therapeutic hypothermia 10, 11.
Early myoclonus, unlike later myoclonus of Lance–Adams syndrome [12], is of prognosis concern and appears in comatose survivors during the first days after cardiac arrest. Myoclonus can originate in cortical, reticular and/or spinal structures. Subcortical myoclonus is not associated with epileptiform activity but EEG recording can demonstrate bursts synchronous with the jerks. Cortical myoclonus consists of brief and multifocal touch-sensitive jerks of distal peripheral muscles on both sides of the body and is characterized by epileptiform activity on EEG recording 13, 14. Postanoxic status epilepticus (PSE) is an electrographic entity characterized by epileptiform activity on EEG recording that is inconstantly associated with early myoclonus 2, 15.
Interestingly, early myoclonus prognostic significance was reassessed by Fugate [16] and Rossetti [17] that demonstrated contrasting results since the therapeutic hypothermia era. Favorable outcomes have been reported in patients with PSE [2]. Moreover, in a retrospective study, PSE was independently associated with hospital mortality, emphasizing the need for effectively treating this complication [15]. The prognostic significance of PSE has not been evaluated prospectively as an independent factor of outcome since the introduction of therapeutic hypothermia. We conducted a prospective observational cohort study of adult survivors of cardiac arrest to determine 1-year mortality and functional outcomes and to assess the prognosis significance of PSE.
Section snippets
Materials and methods
The ethics committee of the French Society for Critical Care approved this prospective observational study.
Results
The patient flow chart is shown in Fig. 1. Of the 174 patients admitted to the ICU for postanoxic coma during the 5-year study period, 68 did not meet the inclusion criteria, leaving 106 patients for the study.
Discussion
In this prospective study of 106 patients with coma after cardiac arrest, 72 (67.9%) patients died within 1 year after cardiac arrest and only 31 (29.3%) had a good recovery defined as a CPC score of 1 or 2. PSE developed in 33 (31%) patients early after the restoration of spontaneous circulation, of whom only 2 (6%) were alive with a good recovery after 1 year. By multivariable analysis, PSE was the strongest factor independently associated with a poor outcome (CPC > 2).
Previous studies of
Contributors
SL conceived, designed, and supervised the trial. SL, JH, SM, JP and GT collected the data; and SL coordinated the data collection. SL, JH, and MRR analyzed and interpreted the data. MRR was in charge of the statistical analysis. SL, JH, and SM wrote the first draft of the paper. All authors approved the final version of the manuscript.
Conflicts of interest statement
We have no conflicts of interest.
Collaborators
The following collaborators participated in the study: Juliette Audibert, Intensive care unit (site investigator), CH André Mignot, Le Chesnay (78); Aihem Yehia, Intensive care unit (site investigator), CH André Mignot, Le Chesnay (78); Hager Ben Mokhtar, Intensive care unit (site investigator), CH André Mignot, Le Chesnay (78); Nathalie Abbosh, Intensive care unit (site investigator), CH André Mignot, Le Chesnay (78); Pierrick Cronier, Intensive care unit (site investigator), CH André Mignot,
Acknowledgment
We thank A. Wolfe, MD, for helping to prepare the manuscript.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.11.001.