We describe two cases of symptomatic ictal bradycardia associated with temporal lobe seizures. We seek to provide support for the importance of evaluating for ictal bradycardia in patients with recurrent or unusual syncope. 

Seizures are commonly associated with arrhythmias, tachycardia being the most common (70-90% of cases). Ictal bradycardia, defined as a drop in heartrate below 60 beats per minute (bpm) during seizure, is found in less than 5% of seizures, and is most commonly associated with temporal lobe seizures. It is hypothesized that autonomic changes during seizures, including ictal bradycardia and asystole, are underlying mechanisms of sudden unexplained death in epilepsy patients (SUDEP), which accounts for 8-17% of deaths in epilepsy.

We reviewed the ictal EEG, EKG, and cardiac monitoring data in two patients with episodes of atonia of unclear etiology, both had temporal lobe seizures associated with bradycardia, and subsequent syncope.

Both patients had ictal bradycardia, seen as a drop in heart rate on EKG corresponding to electrographic seizure on EEG. Patient 1, a 29 year old male, initially presented with episodes of syncope as a child. During monitoring he had a left temporal lobe seizure on EEG, followed by bradycardia to 41 bpm then asystole, leading to atonia and syncope. Patient 2, a 66 year old male had a right temporal lobe focal seizure for 60 seconds leading to bradycardia of 40 bpm, followed by prolonged asystole resulting in syncope. Cardiology evaluated the patient and pacemaker was implanted immediately. Additional cardiac monitoring in both patients revealed no arrhythmias or underlying cardiac abnormalities.

Ictal bradycardia or asystole leading to syncope may accompany temporal lobe seizures, and should be considered in the differential diagnosis for refractory syncope. EEG, EKG, and cardiac monitoring should be done to dictate further management, which may prevent bradycardia, asystole and possibly SUDEP.