Epileptic patients often experience obstructive sleep apnea (OSA) which exacerbates the condition and affects the treatment plans. Emerging evidence suggests that vagal nerve stimulators (VNS) used as adjunctive therapy for drug-resistant epilepsy (DRE) may increase the risk of developing OSA or worsening preexisting cases. This research examines the relapse of sleep apnea in a patient treated with VNS after previous surgical procedures and significant weight reduction, highlighting the complex relationship between epilepsy treatment and sleep disorders.
A 29-year-old male developed temporal lobe epilepsy (TLE) two years after experiencing viral meningitis in 1995. His seizures remained unresponsive to all combinations of anti-seizure medications (ASMs) including trials of cannabidiol and the ketogenic diet. In 2003, doctors diagnosed him with obstructive sleep apnea (OSA) through home sleep testing following his tonsillectomy. In 2005, he underwent uvulopalatopharyngoplasty (UPPP) that led to a dramatic 64-pound weight loss, reducing his body mass index (BMI) from 34.7 to 25.8 kg/m². As a result, his OSA symptoms resolved, eliminating the need for continuous positive airway pressure (CPAP) therapy.
In 2013, the surgical center diagnosed the patient with a left lesional corticoamygdalectomy during the first stage of a two-stage surgical procedure. However, the patient opted not to undergo the additional resection procedures due to concerns about potential memory deterioration. In 2019, the patient received a Vagus Nerve Stimulator (VNS) implant (SenTiva™ M1000) and underwent a stepwise increase in output current (OC) until it reached 1.75 mA.
After VNS activation, the patient experienced temporary hoarseness, shortness of breath, and a sensation of improper breathing in the throat and struggled with poor sleep quality, persistent daytime sleepiness, and worsening nighttime snoring. A home sleep study in 2021 revealed moderate OSA with an apnea-hypopnea index (AHI) of 18.5 events per hour of sleep. Sleep-disordered breathing events occurred three to four times every ten minutes aligning with VNS stimulation cycle duration of three minutes.
The patient did not show improvement despite attempts to reduce OC stimulation to 1.625 mA combined with dental appliances and CPAP therapy. Due to persistent seizure activity and unresolved sleep disorders, the patient underwent VNS explantation in 2022. Following the explanation, the patient experienced the elimination of snoring symptoms, improved sleep quality, and reduced daytime sleepiness. Diagnostic testing included stereo-electroencephalography followed by a left anterior temporal lobectomy in 2023. This intervention resulted in complete seizure control, which has lasted for two years.
This case demonstrates that VNS can trigger the persistence of OSA in patients who previously experienced successful treatment with UPPP and significant weight reduction.
The recurrence of apnea events during VNS activations suggests a direct association between this treatment and newly reported cases of obstructive sleep apnea. BMI reduction didn’t prevent OSA recurrence, as a different mechanism appears to be responsible for this occurrence.
Studies demonstrate that OSA develops in 37.5% of patients diagnosed with DRE who undergo VNS implantation compared to 16.7% prior to VNS use. Brainstem-mediated changes during respiration, along with supraglottic muscle collapse and vocal cord paresis, have been proposed as potential contributors to OSA. Research shows that OSA typically emerges at a 1.25-2.0 mA OC threshold before becoming more severe as the device settings are increased.
A patient recurrence was observed at a 1.75 mA threshold, which is consistent with previous research data. Healthcare providers should be vigilant about VNS-induced OSA and screen patients who have previously received OSA therapy. Sleep-disordered breathing can cause a relapse in seizure control. Therefore, addressing these breathing disorders can lead to better seizure frequency stability and improved tolerance to VNS titration.
Severe epileptic patients who receive VNS implants may develop OSA even in the absence of obesity or previous surgical interventions. Following VNS implantation, it is essential for healthcare providers to screen for OSA signs like sleep disturbances, as untreated OSA can negatively affect seizure control outcomes. If OSA develops post-VNS therapy, then surgeons consider alternative treatment options like device explantation or other surgical procedures to optimize the recovery.
References: Fisk DCP, Ng MC. Recurrent obstructive sleep apnea precipitated by vagus nerve stimulator despite weight loss and uvulopalatopharyngoplasty. Epilepsia Open. Published online 2025. doi:10.1002/epd2.20334
