Abstracts

Rationale: Apnea in infants can be caused by various pathophysiological mechanisms. The apneic seizure is rarely captured on routine EEG. Critical conditions of apnea can be life-threatening events. Recently, focal onset seizures from insula have been reported to provoke apnea on prolonged video EEG. In addition, positron emission tomography (PET) and ictal single-photon emission computerized tomography (SPECT) revealed insula onset focal seizures in patients with apnea. The aim of the present study is to expertise the possibility that focus of apneic seizure in infants is insular cortex. Methods: We collected five infants (3 females) with apneic seizures from January 2010 to May 2019 in The Hospital for Sick Children, Toronto. Clinical data and video EEG findings were retrospective analyzed. Results: The age of onset of apneic events ranged from 4 to 12 months old. The video EEG was performed from 5 to 13 months old. Three of them had no underlying disease, one had mutation of SCN8A gene and the other had Williams syndrome. Four patients underwent routine 30 minutes video EEG. There were no apneic events, neither interictal epileptiform discharges. Prolonged 17-71 hours video-EEG captured 1-3 apneic events. Ictal EEG in all cases showed diffuse delta activities before apneic events. One patient had paroxysmal four limb tonic extension with following abrupt apnea. The other 4 patients had only apneic events without convulsive seizures. O2 saturation decreased 4.5-60% during apneic seizures. Two patients had bradycardia during seizures, up to 6 second asystole. Interictal EEG showed no epileptiform discharges in awake and very rare and subtle epileptiform discharges in non-REM sleeping. Interictal MEG showed clustered spike dipoles in the left posterior insula along with left temporal cortical dysplasia in one patient. MRI in the other 4 patients had no lesion. The antiepileptic medications controlled the apneic seizures in four patients (phenobarbital, 1; acetazolamide, 1; oxcarbazepine and levetiracetam, 1; carbamazepine, 1). Ketogenic diet was effective in one patient. Conclusions: The diagnosis of apneic seizures in infants on EEG is rare because most of routine 30 minutes recording EEGs are normal. We found apneic events with preceding ictal EEG findings on the prolonged video-EEG. The normal EEG findings without epileptiform discharges, apneic seizures and bradycardia of autonomic symptoms might indicate deep seated focal onset autonomic seizures from insula in a subset of infants with apneic seizures. Funding: No funding