Showing posts with label Vagal. Show all posts
Showing posts with label Vagal. Show all posts

Thursday 5 April 2018

Transcutaneous Vagal Nerve Stimulation - a Potential Cognitive Therapy?

 Sham device left and the real one on the right

In older posts there was quite a lot written about the vagal nerve and a method of stimulating it, called vagal nerve stimulation (VNS). VNS is already used by many thousands of people with epilepsy; more recently a much milder kind of stimulation has been developed to improve learning after a stroke.
This kind of therapy requires a 40 minute operation to attach the device inside the body. Even though it looks like VNS makes a dramatic improvement in rehabilitation following a stroke, I do not see children without epilepsy being fitted with internal VNS devices any time soon.
Traditionally VNS requires making a connection directly to the main vagus nerve, however the vagus nerve has many branches leading to it.
A German company Cerbomed has created a non-invasive, transcutaneous (through the skin) VNS device (tVNS) that stimulates the afferent auricular branch of the vagus nerve located in your ear.
“This device has received CE approval as indication that it complies with essential health and safety requirements. Thus, tVNS is safe and accompanied only by minor side effects such as slight pain, burning, tingling, or itching sensation under the electrodes.  
Given that the right vagal nerve has efferent fibers to the heart, tVNS is safe to be performed only in the left ear.”
There are several kinds of electric and magnetic stimulation already used in autism - Transcranial Magnetic Stimulation (TMS), transcranial direct current stimulation (tDCS) and ECT.
ECT was covered in this post:-

Manuel Casanova, neuropathologist and bilingual autism blogger is a fan of TMS

Transcranial direct current stimulation (tDCS) is a form of neurostimulation that uses constant, low direct current (DC) delivered via electrodes on the head; it can be contrasted with cranial electrotherapy stimulation which generally uses alternating current (AC) the same way.
It was originally developed to help patients with brain injuries or psychiatric conditions like major depressive disorder.


The authors present a case of an 18-year old patient with ASD treated successfully with tDCS; 1.5 mA of tDCS was applied once a day for 30 minutes for 8 consecutive days with the anode electrode over rTPJ (CP6 in the 10/10 electroencephalogram system) and the cathode electrode placed on the ipsilateral deltoid. Behavioral outcome was assessed using the Autism Treatment Evaluation Checklist prior to tDCS, after the final tDCS session, and at 2 months after tDCS. An additional, informal follow-up was also made 1 year after tDCS.


Autism Treatment Evaluation Checklist showed substantial improvement in social functioning from baseline to post-tDCS, which was maintained at 2 months. The patient also reported lessened feelings of anger and frustration over social disappointments. Informal follow-up 1 year after stimulation indicates that the patient continues to maintain many improvements.


Anodal tDCS to the rTPJ may represent an effective treatment for improving social functioning in ASD, with a larger clinical trial needed to validate this effect.

Conclusions—This study provides the first evidence that VNS paired with rehabilitative training after stroke (1) doubles long-lasting recovery on a complex task involving forelimb supination, (2) doubles recovery on a simple motor task that was not paired with VNS, and (3) enhances structural plasticity in motor networks.

Scientific Explanation of VNS Paired Stimulation for Tinnitus and Stroke Rehabilitation

Each time the vagus nerve is stimulated, it sends a signal up to the brain, which triggers the release of neurotransmitters (acetylcholine and norepinephrine)   broadly across the brain thus enabling neuroplasticity. In effect it is telling the brain to pay attention to the task at hand.
In someone having therapy after a stroke this might be learning to open a jar, but in autism it might be speech therapy.

The image below illustrates the therapy in action. While the patient is performing a rehabilitative exercise, the physical therapist pushes a button, which triggers the wireless transmitter to send a signal to the implanted device to deliver a small burst of electrical stimulation to the vagus nerve.

big clinical trial:-

It does seem that using electricity in one way or another does have some therapeutic effect in some people with autism. The reason it may be effective in some people is not always entirely clear.
Personally, I like the idea of tVNS to potentially give a learning boost during 1:1 therapy to struggling learners with autism, just as VNS is being used in elderly people who have lost function in their limbs after a stroke and need to relearn how to control their muscles.
It appears that the amount of electricity used in stroke patients is much lower (one 60th) than in those with epilepsy. Perhaps it will be possible to develop a tVNS therapy that does cause any discomfort in the patient’s ear.  
Nobody is researching transcutaneous vagal nerve stimulation for improved learning in autism, given that some doctors at leading hospitals like Johns Hopkins do seem to like zapping people with autism, perhaps somebody should. There looks to be more science behind this than some other shock treatments, which do look quite crude, but do seem to help some people.  

Parkinson’s Disease and the Vagal Nerve
We saw in an earlier post that what goes on in the gut is communicated to the brain, bypassing the blood brain barrier, via the vagal nerve.  In that post it was mice who had their vagal nerve severed in the name of science.
Until recently a common therapy in humans with peptic ulcers was to severe the vagal nerve.  It turns out that these people are protected from developing Parkinson’s Disease. Interesting?