The ictal bradycardia syndrome: localization and lateralization

Area of Science:

• Neuroscience
• Cardiology
• Epileptology

Background:

• The insular cortex and temporal lobe play crucial roles in cardiovascular autonomic control.
• Previous research suggested lateralization of cardiac sympathetic (right insula) and parasympathetic (left insula) function, with left temporal/insular activity potentially causing ictal bradycardia.

Purpose of the Study:

• To critically evaluate the predictive value of ictal bradycardia for seizure localization and lateralization.
• To investigate the relationship between ictal bradycardia and seizure onset/lateralization.

Main Methods:

• Review of 13 patients with ictal bradycardia during video-electroencephalography (EEG) monitoring.
• Identification of seizure and bradycardia onset localization.
• Comprehensive literature review of ictal bradycardia cases and seizure localization.

Main Results:

• All studied ictal bradycardia cases were associated with temporal lobe-onset seizures.
• No consistent lateralization of seizure activity was found at seizure or bradycardia onset in the patient cohort.
• Seizure activity was bilateral at bradycardia onset in 9 of 13 patients; literature review also indicated a predominance of bilateral activity.

Conclusions:

• Ictal bradycardia is frequently associated with bilateral hemispheric seizure activity.
• Ictal bradycardia is not a consistent lateralizing sign for seizure onset localization.
• The data do not support a strictly unilateral parasympathetic cardiomotor representation in the left hemisphere.