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Ann Neurol. 2016 Aug;80(2):175-84. doi: 10.1002/ana.24697. Epub 2016 Jun 28.

Clinically distinct electroencephalographic phenotypes of early myoclonus after cardiac arrest.

Author information

1
Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA.
2
Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA.
3
Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA.
4
Department of Neurology, University of Pittsburgh, Pittsburgh, PA.
5
Department of Neurology, Pittsburgh VA Medical Center, Pittsburgh, PA.

Abstract

OBJECTIVE:

We tested the hypothesis that there are readily classifiable electroencephalographic (EEG) phenotypes of early postanoxic multifocal myoclonus (PAMM) that develop after cardiac arrest.

METHODS:

We studied a cohort of consecutive comatose patients treated after cardiac arrest from January 2012 to February 2015. For patients with clinically evident myoclonus before awakening, 2 expert physicians reviewed and classified all EEG recordings. Major categories included: Pattern 1, suppression-burst background with high-amplitude polyspikes in lockstep with myoclonic jerks; and Pattern 2, continuous background with narrow, vertex spike-wave discharges in lockstep with myoclonic jerks. Other patterns were subcortical myoclonus and unclassifiable. We compared population characteristics and outcomes across these EEG subtypes.

RESULTS:

Overall, 401 patients were included, of whom 69 (16%) had early myoclonus. Among these patients, Pattern 1 was the most common, occurring in 48 patients (74%), whereas Pattern 2 occurred in 8 patients (12%). The remaining patients had subcortical myoclonus (n = 2, 3%) or other patterns (n = 7, 11%). No patients with Pattern 1, subcortical myoclonus, or other patterns survived with favorable outcome. By contrast, 4 of 8 patients (50%) with Pattern 2 on EEG survived, and 4 of 4 (100%) survivors had favorable outcomes despite remaining comatose for 1 to 2 weeks postarrest.

INTERPRETATION:

Early PAMM is common after cardiac arrest. We describe 2 distinct patterns with distinct prognostic significances. For patients with Pattern 1 EEGs, it may be appropriate to abandon our current clinical standard of aggressive therapy with conventional antiepileptic therapy in favor of early limitation of care or novel neuroprotective strategies. Ann Neurol 2016;80:175-184.

PMID:
27351833
PMCID:
PMC4982787
DOI:
10.1002/ana.24697
[Indexed for MEDLINE]
Free PMC Article

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