Case Presentation: A 32-year-old female with focal epilepsy presented with several episodes of drop attacks with associated loss of consciousness (LOC). There were no witnessed tonic-clonic movements or prolonged post-event confusion. There were no prodromal symptoms including chest pain, palpitations, or features of increased parasympathetic tone. Vital signs and physical exam were normal. Initial electrocardiogram (ECG), echocardiogram, brain imaging, and laboratory workup were unrevealing. Simultaneous electroencephalogram (EEG) and ECG monitoring in the epilepsy monitoring unit revealed an asystolic pause of ten seconds associated with epileptiform activity during an episode, consistent with ictal asystole. Electrophysiology was consulted and the patient ultimately underwent dual-chamber permanent pacemaker (PPM) placement. The patient has had no recurrence of the episodes to date, now more than a decade since presentation.
Discussion: Ictal syncope is a rare phenomenon that occurs in association with 0.002–0.4% of seizures and represents a unique pathophysiological convergence of cardiac syncope and epilepsy. Bradyarrhythmias are infrequently associated with epileptic seizures. Ictal bradycardia is defined as prolongation of R-R interval beyond 2 seconds on ECG and ictal asystole is defined as absence of ventricular complexes for at least 4 seconds. In current medical dogma, syncope and seizure are considered distinct clinical entities and both are possible causes of transient LOC with loss of postural tone. Guidelines describing the algorithmic approach to LOC generally recommend the clinician to differentiate between acute seizure and true (isolated) syncope. The etiologies of isolated syncope are further classified as cardiac (structural and arrhythmic), vasovagal (neurocardiogenic), and postural (orthostatic). Patients presenting with LOC should ubiquitously undergo basic cardiac and neurologic workup. Concurrent EEG/ECG monitoring is essential to making the diagnosis of ictal syncope. The management of patients diagnosed with ictal syncope involves the optimization of their anti-epileptic regimen and consideration for epilepsy surgery. If there are ongoing syncopal episodes with associated ictal asystole > 6 seconds, particularly despite medical therapy, electrophysiology should be consulted evaluated for PPM candidacy. PPM insertion limits morbidity and may have a mortality benefit in selected cases, though many of these patients are not pacemaker-dependent.
Conclusions: Ictal asystole is an uncommon cardio-neural phenomenon seen in epilepsy syndromes whereby a seizure causes asystole leading to syncope. This presentation illustrates a unique diagnostic challenge in the co-occurence of two, usually non-coincident causes, of LOC. Ictal bradyarrhythmia and asystole should be suspected as a possible cause of syncope in young, healthy patients, in the absence of other symptoms and a history of epilepsy. Further research is needed to elucidate the pathophysiology, risk factors, clinical clues, and the survival benefit of PPM placement in ictal syncope.