Epilepsy & behavior : E&B
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Epilepsy & behavior : E&B · Sep 2020
Circadian distribution of autostimulations in rVNS therapy in patients with refractory focal epilepsy.
Responsive vagus nerve stimulation (rVNS) utilizes an electrocardiograph (ECG)-based algorithm to detect rapid sympathetic activations associated with the onset of a seizure. Abrupt sympathetic activation may also be associated with nocturnal arousals between sleep cycles or transitioning from sleep to wakefulness, a period in which many patients with epilepsy experience seizures. Because of circadian changes in autonomic function, we hypothesized that the autostimulation feature might also behave in a circadian fashion. ⋯ Early morning peaks of autostimulations at low thresholds may reflect awakening-induced activation of the cardiovascular system, which is associated with a shift towards the dominance of the sympathetic branch of the autonomic nervous system. Cortisol release occurs in parallel driven by wakening-induced activation of the hypothalamic-pituitary-adrenal axis, which is fine-tuned by direct sympathetic input to the adrenal gland. This is of interest considering the known sympathetic hyperactivity in patients with epilepsy.