Hypoglossal nerve stimulation in a pig model for evaluation of genioglossus muscle force with different stimulation parameters.

Hypoglossal nerve stimulation (HNS) is indicated in the treatment of patients with moderate to severe obstructive sleep apnea (OSA) who fail or cannot tolerate positive airway pressure treatments. However, the availability of preclinical models is limiting further optimization of the HNS. This study aimed to develop a preclinical model to evaluate contraction force of genioglossus muscle following HNS. Male anesthetized pigs were surgically dissected to locate the genioglossus muscles and hypoglossal nerves. Muscle contraction force following electrical stimulation was studied using two protocols including single twitch and pulse train. Single twitch experiments demonstrated that muscle contraction force increased with amplitude until reaching a plateau, with strong fits to sigmoidal curves. The more gradual slope observed at shorter pulse durations suggests that amplitude titration at these pulse durations enables finer adjustment of treatment intensity, potentially improving patient tolerability. Pulse train experiments showed increase in force generation and fusion index with increasing frequency. The findings were reproducible across the animals with acceptable variations between animals. This HNS model in pigs can be a reliable and effective tool in evaluating activation of genioglossus muscle with variations in stimulation parameters and complement existing models of upper airway expansion.