Abstracts

Rationale: To determine the frequency and seizure characteristics for ictal hypoxemia (defined as an oxygen saturation less than 90%) and ictal bradycardia (defined as a heart rate less than the second percentile for age) in children. Methods: The electronic records of children, aged 1 month to 18 years, who were admitted to the Epilepsy Monitoring Unit for routine video-EEG monitoring between 11/1/2007 and 3/13/2009, were reviewed retrospectively. Those children who had at least one partial complex or generalized convulsive seizure with recorded oximetry and/or heart rate data were identified. The actual video-EEG recordings were reviewed to determine seizure type, duration, lateralization, lobar localization (temporal versus extratemporal), and oxygen saturations/heart rates before, during, and after the seizure. Results: 51 children were identified (all of whom had heart rate data and 49 of whom had oxygen saturation data). The mean age was 9.2 +/- 5.5 years, and 62.7% were male. 234 seizures (all of which had heart rate data and 224 of which had oxygen saturation data) were analyzed (mean number of seizures per child 6.8 +/- 8.6, range 1-46). Ictal hypoxemia was observed in 47% of children and 23% of seizures. Ictal hypoxemia was significantly more likely to occur during generalized seizures (28/160 partial complex, 28/64 primary or secondarily generalized, Chi squared p<0.001) and in children who underwent AED reduction/withdrawal (12/16 children who underwent AED reduction/withdrawal, 11/33 who did not, Chi squared p=0.006). For partial complex seizures, the presence of ictal hypoxemia was associated with prolonged seizure duration (252 +/- 329.7 seconds with hypoxemia, 51.9 +/- 62.2 seconds without, independent samples T test p<0.02). Of the 116 partial seizures with clear onset lateralization, ictal hypoxemia tended to be more prevalent in those with right hemispheric onset (10/40 right, 9/76 left, Chi squared p=0.07). However, this was not statistically significant. Ictal bradycardia occurred in 7.8% of children and 3.1% of seizures. Ictal bradycardia was more common in children whose AEDs were reduced/withdrawn (3/16 children who underwent AED reduction/withdrawal, 1/35 who did not, Chi squared p=0.05). Ictal bradycardia was solely observed with extratemporal onset partial complex seizures (8/103); it was not seen in primary/secondarily generalized or temporal onset partial complex seizures. However, these differences were not statistically significant. No correlation was noted between the duration or lateralization of partial complex seizures and the presence of ictal bradycardia. There was also no correlation between the presence of ictal bradycardia and ictal hypoxemia.