Acute Posthypoxic Myoclonus After Pediatric Cardiac Arrest: EEG Correlates and Outcome

Posthypoxic myoclonus (PHM) is associated with a poor prognosis in adults. Studies on this topic are limited in pediatrics. We aim to describe the incidence, EEG features, and outcomes of PHM after pediatric cardiac arrest (CA).

This is a 3-year retrospective single-center review of pediatric patients with CA. Patients with known cerebral injury and/or epilepsy and those admitted to the cardiac intensive care unit were excluded. Chi-square analysis was used to assess associations of PHM with mortality and cerebral injury. Further analysis compared these outcome metrics between patients with PHM and those without PHM but with cerebral injury, severe EEG background abnormalities, and/or electrographic seizures.

A total of 106 patients met inclusion criteria (median age 2.5 years [interquartile range 0.67-10.6 years], 30% [32/106] female). Ten patients had PHM (9%, 10/106), and 80% (8/10) had an EEG correlate. Patients with PHM had increased rates of brain injury (100% vs 53%, p = 0.005) and mortality (90% vs 38%, p = 0.002) compared with the entire group. When comparing patients with PHM with patients with brain injury or severe EEG background abnormalities, there was no difference in mortality.

PHM is common after pediatric CA and is associated with brain injury and mortality.