Ictal bradycardia in partial epileptic seizures: Autonomic investigation in three cases and literature review

Ictal bradycardia is a rare, probably underestimated, manifestation of epileptic seizures whose pathophysiology is still debated. Autonomic modifications may result either from a sympathetic inhibition or from a parasympathetic activation probably due to the ictal discharge arising from or spreading to the structures of the central autonomic network. We review 60 cases of ictal bradycardia from the available literature and present three additional cases associated with left temporal lobe seizures studied by autonomic polygraphic ictal monitoring. Only 47 of the 63 reported cases were documented by simultaneous EEG and ECG recordings during an attack. About 76% of patients in whom well-localized ictal discharges were recorded had temporal or frontotemporal lobe seizures. Forty-five cases included information allowing confident localization of the side of ictal onset, and a 26 : 19 ratio of the left versus right side was evident. Simultaneous monitoring of ECG and other autonomic parameters during EEG recording in partial seizures should be performed to gain more insight into ictal semiology. Correlation of the symptoms referred to by patients with changes in autonomic parameters could avoid erroneous diagnosis of non-epileptic attacks and disclose a potentially lethal condition. Our cases confirm the preferential role of the left hemisphere in the genesis of ictal bradycardia and shed light on the relationship between suprabulbar control of autonomic function and partial epileptic seizures.