Newly published in the Brain Stimulation Journal, a first of its kind open-label prospective comparative study assessing vagus nerve stimulation (VNS) showed significant improvement in daytime sleepiness among patients with narcolepsy, suggesting that this type of neurostimulation could be a promising nonmedical treatment in narcolepsy.1
Among 36 patients compared with the baseline (Epworth Sleepiness Scale [ESS], 15.9; ±2.5), the group of patients with narcolepsy (n = 18) showed a significant improvement on ESS after 3 months (ESS, 11.2; ±3.3; P <.05) and 6 months (ESS, 9.6; ±2.8; P <.001) on VNS therapy. The investigators did not observe a significant ESS-improvement in patients without narcolepsy who received VNS treatment (n = 18) (baseline, 14.9 [±3.9]; 3 months, 13.6 [±3.7]; 6 months, 13.2 [±3.5]; P = .2).
Top Clinical Takeaways
- Vagus nerve stimulation demonstrated a significant reduction in daytime sleepiness exclusively among patients with narcolepsy, emphasizing its potential as a complementary treatment for those who don't respond to conventional drugs.
- The study highlights neurostimulation as a promising innovative approach to managing excessive daytime sleepiness in narcolepsy, potentially sparing patients from polytherapy and improving treatment adherence.
- While acknowledging study limitations, including the absence of blinding and a sham-controlled group, the authors encourage future randomized studies to explore the effectiveness of vagus nerve stimulation in narcolepsy treatment.
“We intentionally compared patients with narcolepsy and patients without narcolepsy experiencing daily sleepiness in this study in order to detect the possible disease-specific effect of VNS in narcolepsy. Comparison of VNS with the best medical treatment in narcolepsy was out of the scope of our study,” senior author Sergiu Groppa, MD, PhD, professor of neurology at University Medical Center of the Johannes Gutenberg University Mainz, and colleagues wrote.1 “Interestingly, the effect on ESS was specific for the patients with narcolepsy, since no statistically significant changes were observed in patients without narcolepsy. The attested improvement in daytime sleepiness was independent from the antidepressant effect of VNS. It is worth to mention that the positive effects of VNS on daytime sleepiness in patients with narcolepsy were more notable with increased duration of VNS.”
READ MORE: Daytime Continuous Polysomnography Provides Reliable Diagnosis of Pediatric Narcolepsy Type 1
Investigators evaluated the therapeutic effect of VNS on daily sleepiness and cataplexies in narcolepsy. In this study, patients with narcolepsy who were treated with VNS because of depression or epilepsy were compared with controls without narcolepsy treated with VNS for depression or epilepsy (mean age, 31.5 years; ±8.2). The investigators assessed daily sleepiness using ESS and weekly cataplexy rate (WCR) before the implantation of VNS and at 3- and 6-month follow-ups.
Indication for VNS implantation was epilepsy in 22 patients (61.1 %) and depression in 14 patients (38.9 %). There were 10 patients who had narcolepsy type 1 (NT1; 55.6 %) and 8 patients who had narcolepsy type 2 (NT2; 44.4 %). Those with narcolepsy received medications including modafinil in 8 (44.4 %), methylphenidate in 3 (16.7 %), pitolisant in 7 (38.9 %), solriamfetol in 4 (22.2 %), sodium oxybate in 4 (22.2%), selective serotonin reuptake inhibitors in 5 (27.8 %), and clomipramine in 2 (11.1 %).
Among the patients with narcolepsy, investigators observed a trend in improvement of number of cataplexies per week following 6 months (WCR, 1.8; ±2.1) compared with baseline (WCR, 3.9; ±4.5). Despite this observation, it did not reach a statistically significant difference (P = .09) in this set of patients. In addition, the mean WCR after 3 months with VNS was 2.8 (±3.1) in those with narcolepsy and did not differ from baseline. Notably, investigators did not observe any differences between the study groups with adverse effects.
