The Ictal Bradycardia Syndrome

PURPOSE: Episodic loss of consciousness presents a diagnostic challenge to the neurologist. A perhaps underrecognized cause of episodic loss of consciousness, which we call the ictal bradycardia syndrome, occurs when epileptic discharges profoundly disrupt normal cardiac rhythm, resulting in cardiogenic syncope during the ictal event. We attempt to determine whether the presence of the ictal bradycardia syndrome provides localizing information regarding the site of seizure onset and to describe the demographics of patients with this syndrome. We also discuss difficulties in diagnosis and treatment. METHODS: We review 23 cases of the ictal bradycardia syndrome from the literature and present four additional cases. Brief histories are provided for the four previously unreported cases. Where data are available, cases are analyzed with respect to age, sex, and site of seizure onset. RESULTS: Patients with the ictal bradycardia syndrome ranged from 4 months to 72 years (mean 39 years). There was an approximately 5:1 ratio of males to females. Twenty of the 23 patients (87%) whose site of ictal onset could be localized had temporal lobe epilepsy, although no clear lateralizing predominance was apparent. CONCLUSIONS: The ictal bradycardia syndrome should be considered in patients with unusual or refractory episodes of syncope, or in patients with a history suggestive of both epilepsy and syncope. It suggests seizure onset in temporal lobe, and is more commonly diagnosed in males. Diagnosis may be aided by ambulatory EEG/ECG monitoring. Cardiac pacemaker implantation along with antiepileptic drug therapy may be necessary to minimize the possibility of death.