- •Transcutaneous vagal nerve stimulation (tVNS) increases heart rate variability and alters cardiovascular autonomic control towards parasympathetic predominance
- •tVNS causes a decrease in vasoconstrictor sympathetic nerve activity recorded using microneurography.
- •As sympathoexcitation is a hallmark of many conditions, including heart failure, tVNS may be a simple and inexpensive therapy for such conditions.
Turns out someone has done part of my study! Granted, they didn’t incorporate acupuncture and they used a slightly different part of the ear, AND 30hz instead of 2 hz. They showed an increase in HRV in their subjects, which I have not consistently shown in the clinic.
Noninvasive vagus nerve stimulation in healthy humans reduces sympathetic nerve activity
http://www.brainstimjrnl.com/article/S1935-861X%2814%2900260-5/abstract
Highlights
Abstract
Background
Vagus nerve stimulation (VNS) is currently used to treat refractory epilepsy and is being investigated as a potential therapy for a range of conditions, including heart failure, tinnitus, obesity and Alzheimer’s disease. However, the invasive nature and expense limits the use of VNS in patient populations and hinders the exploration of the mechanisms involved.
Objective
We investigated a non-invasive method of VNS through electrical stimulation of the auricular branch of the vagus nerve distributed to the skin of the ear – transcutaneous VNS (tVNS) and measured the autonomic effects.
Methods
The effects of tVNS parameters on autonomic function in 48 healthy participants were investigated using heart rate variability (HRV) and microneurography. tVNS was performed using a transcutaneous electrical nerve stimulation (TENS) machine and modified surface electrodes. Participants visited the laboratory once and received either active (200 μs, 30 Hz; n = 34) or sham (n = 14) stimulation.
Results
Active tVNS significantly increased HRV in healthy participants (P = 0.026) indicating a shift in cardiac autonomic function toward parasympathetic predominance. Microneurographic recordings revealed a significant decrease in frequency (P = 0.0001) and incidence (P = 0.0002) of muscle sympathetic nerve activity during tVNS.
Conclusion
tVNS can increase HRV and reduce sympathetic nerve outflow, which is desirable in conditions characterized by enhanced sympathetic nerve activity, such as heart failure. tVNS can therefore influence human physiology and provide a simple and inexpensive alternative to invasive VNS.
This breakdown of the innervation of the ear is from a previous blog post. Of interest is that the cymba concha is innervated 100% by the auricular branch of the vagus nerve. The tragus gets 45% from auricular branch of the vagus nerve and 55 from the greater auricular nerve.
well. For details on double innervation see Figures 1B
and 2.
DISCUSSION
The external ear appears only in mammals. The
density of nerve fibers in the human auricle compared
to other regions of the head seems rather high. In
addition, four different nerves are distributed to the
external ear. They are partly branchiogenic and so-
matogenic. Concerning the sensory innervation, there
is a gapin the origin between the first and third
branchiogenic nerves on the upper side and on the
TABLE1.OverviewoftheInnervationPattern
oftheLateralSurfaceoftheAuricle
ABVN GAN ATN
Crus of helix 20% 80%
Spine of helix 9% 91%
Tail of helix 100%
Scapha 100%
Crura of anthelix 9% 91%
Antihelix 73% 9% 18%
Antitragus 100%
Tragus 45% 46% 9%
Cymba conchae 100%
Cavity of concha 45% 55%
Lobule of auricle 100%
ABVN
auricle branch of the vagus nerve; GAN
great auricular nerve; ATN
auriculotemporal nerve
