Effects of transcutaneous auricular vagus nerve stimulation at left cymba concha on experimental pain, parasympathetic activity

True prevention. In my book I highlight two studies in animals where acupuncture prevented an increase in stress response after startling the animal. This, to me, shows the power of prevention using acupuncture. It stabilized your stress response to that you don’t spin out. This is of utmost importance in understanding how acupuncture is so helpful for anxiety and panic attacks.

This study shows a preventative effect of TAVNS on pain, specifically pain withdrawal response AFTER the TAVNS session. And, sure, the effect is mild, but we’re getting more data which can really lead to more effect therapies for chronic pain.

This study investigates the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on pain perception using the nociceptive withdrawal reflex (NWR), a marker linked to chronic pain. Involving 20 healthy adults, the study compared taVNS applied to the left cymba concha versus a sham condition on the earlobe. Results showed that taVNS significantly increased NWR thresholds 10 and 30 minutes post-stimulation, indicating reduced pain perception. Additionally, increased parasympathetic activity during taVNS correlated with greater pain suppression. These findings suggest that taVNS can effectively reduce pain and that parasympathetic activation may predict this pain-suppressing effect, highlighting its potential for managing chronic pain.

Yokota H, Edama M, Kawanabe Y, Hirabayashi R, Sekikne C, Akuzawa H, Ishigaki T, Otsuru N, Saito K, Kojima S, Miyaguchi S, Onishi H. Effects of transcutaneous auricular vagus nerve stimulation at left cymba concha on experimental pain as assessed with the nociceptive withdrawal reflex, and correlation with parasympathetic activity. Eur J Neurosci. 2024 May;59(10):2826-2835. doi: 10.1111/ejn.16305. Epub 2024 Mar 12. PMID: 38469939.

full article here.

Abstract

The aim of this study was to clarify the effects of transcutaneous auricular vagus nerve stimulation (taVNS) to the left cymba concha on the pain perception using nociceptive withdrawal reflex (NWR), which is known to be associated with chronic pain, and to investigate whether there is a relationship between taVNS-induced suppression of the NWR and parasympathetic activation. We applied either 3.0 mA, 100 Hz taVNS for 120 s on the left cymba concha (taVNS condition) or the left earlobe (Sham condition) for 20 healthy adults. NWR threshold was measured before (Baseline), immediately after (Post 0), 10 min (Post 10) and 30 min after (Post 30) stimulation. The NWR threshold was obtained from biceps femoris muscle by applying electrical stimulation to the sural nerve. During taVNS, electrocardiogram was recorded, and changes in autonomic nervous activity measured by heart rate variability (HRV) were analyzed. We found that the NWR thresholds at Post 10 and Post 30 increased compared with baseline in the taVNS group (10 min after: p = .008, 30 min after: p = .008). In addition, increased parasympathetic activity by taVNS correlated with a greater increase in NWR threshold at Post 10 and Post 30 (Post 10: p = .003; Post 30: p = .001). The present results of this single-blinded study demonstrate the pain-suppressing effect of taVNS on NWR threshold and suggest that the degree of parasympathetic activation during taVNS may predict the pain-suppressing effect of taVNS after its application.

Keywords: LF/HF; heart rate variability; nociceptive withdraw reflex; transcutaneous auricular vagus nerve stimulation; vagus afferent.