John Libbey Eurotext

Epileptic Disorders

The Educational Journal of the

Falsely pessimistic prognosis by EEG in post-anoxic coma after cardiac arrest: the borderland of nonconvulsive status epilepticus Volume 14, issue 3, September 2012

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Authors
Department of Neurology, Department of Physiotherapy, Guy's and St Thomas’ NHS Foundation Trust, London, UK
  • Key words: EEG, post-anoxic coma, nonconvulsive status, repetitive epileptiform discharges, false prediction
  • DOI : 10.1684/epd.2012.0519
  • Page(s) : 340-4
  • Published in: 2012

Background. Prognostication following anoxic coma relies on clinical assessment and is assisted by neurophysiology. A non-evolving EEG spike burst/isoelectric suppression pattern after the first 24 hours almost invariably indicates poor outcome, while an evolving pattern implies nonconvulsive status epilepticus (NCSE) that may “hide” surviving brain activity and is amenable to treatment. Case study. We present the case of a 53-year-old woman who had a witnessed out-of-hospital ventricular fibrillation cardiac arrest, was resuscitated by paramedics, but remained comatose. An EEG, performed 36 hours post-insult, showed an unremitting, non-evolving, unresponsive 2-6 Hz high-voltage spike burst/isoelectric suppression pattern, which remained unchanged at 96 hours post-insult, following therapeutic hypothermia. During this period, she was completely off sedation and taking triple antiepileptic treatment, without systemic confounding disorders. Although the initial pattern was indicative of poor neurological outcome, she eventually made meaningful functional recovery; the last EEG showed satisfactory background rhythms and stimulus-induced epileptiform discharges without seizures. Conclusion. In post-anoxic coma, non-evolving >2 Hz spike burst/isoelectric suppression pattern may still reflect NCSE and therefore should be considered in the diagnostic EEG criteria for NCSE. Such borderline patterns should not dissuade physicians from intensifying treatment until more confident prognostication can be made.