Cardiac Asystole Triggered by Temporal Lobe Epilepsy with Amygdala Enlargement

Abstract

A 25-year-old previously healthy man was hospitalized for syncope. While standing, he suddenly lost consciousness, followed by a generalized tonic clonic seizure. An electrocardiogram demonstrated asystole. No cardiac abnormalities were detected on the echocardiogram, cardiac magnetic resonance imaging (MRI), positron emission tomography, or a coronary angiogram. An electrophysiological study showed normal sinus node and atrioventricular node function. An electroencephalogram revealed small spike waves in the frontotemporal region. Brain MRI demonstrated a left-sided amygdala enlargement. To the best of our knowledge, this is the first case of temporal lobe epilepsy with an amygdala enlargement that induced cardiac asystole. Case ReportA 25-year-old previously healthy man was hospitalized due to a recent history of syncope with a generalized tonic clonic seizure (GTC). He had experienced prodromes consisting of chest discomfort and flashbacks of visual memory. He was currently receiving carbamazepine (CBZ, 400 mg/ day), as prescribed by another medical facility. No abnormal physical findings were noted except for skin rashes on his trunk. His initial electrocardiogram (ECG) and electroencephalogram (EEG) were normal; magnetic resonance imaging (MRI) of the brain also showed no abnormalities. A laboratory examination revealed moderate liver injury along with mild eosinophilia. At this time, CBZ was discontinued due to potential allergic reactions. After 21 days of admission, while standing beside his bed and talking to his physician, he felt prodromes and suddenly lost consciousness, followed by a GTC that lasted for approximately 30 s. He recovered spontaneously without resuscitation. ECG monitoring at this time demonstrated asystole (5 s and 9 s, respectively, Fig. 1A). On the next day, asystole occurred twice along with prodromes (Fig. 1B). However, he did not lose consciousness and no GTC was observed. He was then transferred to the cardiology department for an evaluation of bradyarrhythmia. Results from Holter ECG monitoring, a signal-averaged ECG, and the head-up tilting test were normal. No cardiac abnormalities were detected on the echocardiogram, cardiac MRI with gadolinium contrast agent, fluorodeoxyglucose positron emission tomography/computed tomography, or coronary angiogram. An electrophysiological study showed normal sinus node function and atrial ventricular node function. A repeat EEG showed small spike waves in the fronto-temporal region (Fig. 2). Antiepileptic medication with zonisamide (ZNS, 400 mg/day) was initiated, and the symptoms disappeared. A permanent cardiac pacemaker was not implanted due to the patient's refusal. Subsequently, he was transferred to the neurosurgery department at the Juntendo University Hospital. Repeat MRI of the brain demonstrated a left-sided amygdala enlargement