In a Heartbeat: Autonomic Changes during Seizures

Abstract

Abnormalities in Cardiac and Respiratory Function Observed during Seizures in ChildhoodO'Regan ME, Brown JKDev Med Child Neurol 2005;47:4–9The aim of this study was to observe any changes in cardiac and respiratory function that occur during seizures. Thirty-seven children (20 boys, 17 girls; median age, 7 years 6 months; range, 1 year 6 months to 15 years 6 months) were studied. We recorded electroencephalograms, respiratory rate, heart rate, electrocardiograms, blood pressure, oxygen saturation, heart rate variability (time-domain analysis), and cardiac vagal tone. A respiratory pause was defined as an interruption in respiration lasting more than 3 seconds but less than 15 seconds. Apnea was defined as absence of respiration for more than 15 seconds. Tachypnea was defined as a 10% increase in respiratory rate from the preictal baseline. Bradypnea was defined as a 10% decrease in respiratory rate from the preictal baseline. Significant hypoxia was defined as a saturation of less than 85%. A significant change in heart rate was taken as a 10% increase or decrease below the baseline rate. Data were obtained from 101 seizures: 40 focal seizures, 21 generalized seizures, and 40 absences. Focal seizures were frequently associated with significant respiratory abnormalities, tachypnea in 56%, apnea in 30%, frequent respiratory pauses in 70%, and significant hypoxemia in 40%. The changes seen in respiratory rate were statistically significant. Changes in cardiac parameters, an increase or decrease in heart rate, were observed in only 26% of focal seizures and 48% of generalized seizures. We conclude that seizure activity can disrupt normal physiologic regulation and control of respiratory and cardiac activity.Cardiac Arrhythmias in Focal Epilepsy: A Prospective Long-term StudyRugg-Gunn FJ, Simister RJ, Squirrell M, Holdright DR, Duncan JSLancet 2004;364:2212–2219