Bi-level VNS therapy with different therapy modes at night and daytime improves seizures and quality of life in a patient with drug-resistant epilepsy

• VNS induced or aggravated sleep apnea and by this sleep fragmentation in our patient. • Sleep fragmentation worsens seizures and may antagonize anti seizure effects of vns. • Reduced vns output during night was antidepressant and led to 90% seizure reduction. • This case contributed to the development of a new generator model with bi-level mode. Induction or aggravation of sleep apnea is a known side effect of vagus nerve stimulation (VNS). We report the case of a 44 year old male with drug-resistant epilepsy and depression who did not experience any seizure reduction after 1 year of VNS but a worsening of depression and daytime sleepiness. After confirming VNS-associated sleep apnea we started the first bi-level VNS therapy with standard VNS settings during daytime and reduced settings during nighttime. Anti-seizure medication remained unchanged. Within 12 months his seizure frequency was reduced by 90 % and his depression improved, permitting a cessation of his antidepressant medication. The observations made in this case have contributed to the manufacturer of VNS developing new generator models that can automatically provide bi-level VNS.