Hypercapnic ventilatory response in epilepsy patients treated with VNS: A case-control study

Area of Science:

• Neuroscience
• Respiratory Physiology
• Epilepsy Research

Background:

• Central CO2 chemoreception (CCR) is crucial for regulating breathing.
• An attenuated hypercapnic ventilatory response (HCVR) is linked to respiratory dysfunction and sudden unexpected death in epilepsy (SUDEP) risk.
• Vagus nerve stimulation (VNS) may reduce SUDEP risk, but its effect on CCR is unclear, especially within the first two years post-implantation.

Purpose of the Study:

• To investigate whether chronic VNS affects central CO2 chemoreception (CCR) in epilepsy patients.
• To examine the association between active VNS and the hypercapnic ventilatory response (HCVR).

Main Methods:

• A case-control study compared HCVR in epilepsy patients with and without active VNS.
• HCVR slope (∆ VE/ ∆ ETCO2) was calculated for 86 subjects.
• Univariate and multivariate analyses were performed to identify predictors of HCVR slope.

Main Results:

• The HCVR slope was significantly lower in patients with active VNS compared to controls.
• Active VNS and end-tidal CO2 (ETCO2) were associated with a lower HCVR slope.
• Higher BMI was associated with a higher HCVR slope.

Conclusions:

• Chronic VNS may be associated with an attenuated central CO2 chemoreception (CCR).
• Further prospective studies are needed to establish the time course and causality of this effect.
• Understanding this relationship is crucial for assessing its impact on SUDEP risk.