Electricity Can Trigger Seizures, So How Can an Ear Stimulator Treat Them?

8 Oct

There are two very important questions we have in mind when offering technology to an individual with a disability. The first question is "will this be safe" and the second is, "will this deliver a useful goal for this person". Every stimulator I have supplied comes with a list of reasons not to use it. These are called contraindications and every medical device will list these. Some are "absolute" and present a barrier to the products use in all situations and others are "relative" because there is a potential risk, but a clinician may feel that the benefit of use outweighs that risk in some situations.

Let's consider the RISE Stimulator, a stimulator for denervated muscle made in Austria by Dr. Schuhfried Medizintechnik, which we supply in the UK. We have many users of this product with peripheral nerve injuries, brachial plexus injuries and spinal cord injuries resulting in muscle denervation. It is a product that has been tested extensively prior to being placed on the market. It lists contraindications that are often seen with electrical stimulation products.

Among its contraindications is" "transcerebral therapy in epilepsy": current passed across the head, through the brain, in someone who has seizures and the "Head region of people suffering from seizures". The manual treats these as a local contraindication. It is about where the electrodes go, not about whether the person has epilepsy.

The box of a high-street TENS unit is blunter. So is the NHS page on TENS, which lists "you have epilepsy" among the reasons not to use one. If you live with epilepsy, you've probably seen these statements, and the questions people ask online follow: "what is the likelihood that a tens/ems machine can cause a seizure", or "Does external electricity affect seizures?"

It's an important question to ask.

We now distribute an ear-worn vagus nerve stimulator, the tVNS E from tVNS Technologies in Germany, whose certified purpose includes drug-resistant epilepsy. Instructions for use state this as follows:-

Epilepsies: Reduction of seizure frequency over a period of 28 days during intervention compared to pre-intervention phase of a minimum 25% after a treatment period of 20 weeks.

Until I corrected it this month, one of our own older articles told readers not to stimulate at all when a person has epilepsy. What follows is how I reconcile these two apparent contraindications, as an engineer with fifty years of working with stimulators behind me and no previous caseload in epilepsy.

Why the TENS box says no

The warning gets something right. Nobody should pass current across the head of a person with epilepsy (or anybody else for that matter) casually, and a company selling pain relief units over the counter can't know where its customers will put the pads. Epilepsy Action is softer: people with epilepsy should "speak to their medical professional before using a TENS machine".

Professional guidance is typically narrower. Canadian physiotherapy guidance from 2010 limits the epilepsy caution to electrodes on the head, neck and shoulders, and grades it at a level where harm has been shown only in experimental work, with clinical evidence "either lacking or conflicting" (Physiotherapy Canada 2010). Tim Watson, an author of the UK physiotherapy guidance, writes that people with epilepsy have "long been considered to fall into a 'precaution' category".

The human evidence behind it, as far as I can find, is a single case report. A patient recovering from a stroke had repeated fits after TENS, and the author judged it "more likely than not" that TENS was the trigger (Rosted 2001). A stroke is itself a common cause of seizures, so cause and effect are hard to separate. A review of 381 TENS trials found side effects "poorly reported, generally mild" and never mentioned seizures (Johnson 2022). People with epilepsy were very probably left out of those trials, so the question was never asked.

A 2024 Italian consensus of rehabilitation societies noted that the evidence behind the Canadian guidance "was not systematically collected", and added: "It is a serious matter to exclude a group from research eligibility" (Gianola 2024).

KEY POINT: The warning on the TENS box is a precaution, not a measured harm. It was written for current placed near the head and neck in people nobody had tested, and as a default that is reasonable. It is not evidence that stimulation causes seizures. Where user safety is concerned, there is a natural tendency to be cautious. However, this has to be weighed against the potential benefits from applying carefully chosen stimulation in a particular situation.

Can electricity cause a seizure? Yes, if it reaches the brain

Doctors have used electricity to cause seizures on purpose since 1938, when Ugo Cerletti and Lucio Bini introduced electroconvulsive therapy (ECT) in Rome. Conventional ECT passes 800 to 900 mA through the head (Peterchev 2015).

You need far less if the current goes straight into the brain. Before epilepsy surgery, teams sometimes stimulate the brain surface through implanted electrodes to find where seizures begin. At 1 to 10 mA, that stimulation set off seizures in 23 of 41 people with refractory epilepsy, 56% (Sivaraju 2024).

Here is the part the TENS box can't tell you: the same tool can actually stop seizures. In a review of 40 patients with super-refractory status epilepticus (seizures that continue despite anaesthesia), ECT ended the status in 80% of adults (Dowd 2025). That is a small and selected group. And in a 2025 analysis of 20 randomised trials of non-invasive brain and nerve stimulation in epilepsy, one technique reduced seizures compared with sham: a weak 2 mA current through the scalp. None of the techniques made seizures more frequent (Tseng 2025).

This is the part I can speak to with some authority. One milliamp on the surface of the brain and one milliamp in the skin of the ear are entirely different things. Skin acts as an insulator. What matters is how concentrated the current is when it reaches the tissue you care about, and what it is aimed at. Modelling of ear stimulation puts the strongest electric field in the skin directly under the electrodes (Kreisberg 2021).

KEY POINT: Electricity starts seizures when enough of it is concentrated in the brain, and in the right circumstances it stops them. For any device, the important question is where the current is applied, where it goes and what it is aimed at.

Why the vagus nerve, of all nerves

The vagus is the tenth cranial nerve, and its name, Latin for "wandering", suits it. It leaves the brainstem, runs down the neck and sends branches to the heart, the airways and the entire digestive tract (Berthoud 2000). Most people who know it at all know it as the nerve that slows the heart. in fact, the vagus nerve plays a major role in our autonomic nervous system and our response to stress.

What makes it useful in epilepsy is the traffic running the other way. Most of its fibres, 80% to 90% by one review's estimate, carry information from the organs up to the brain rather than instructions down from it (Breit 2018).

That information arrives at a relay in the brainstem, the nucleus of the solitary tract, which connects onwards to other brainstem centres, including the locus coeruleus, a small cluster of cells that releases noradrenaline across much of the brain. The researchers who mapped these connections concluded that their "massive central projections" are likely to be why stimulating the vagus can reduce seizures (Berthoud 2000).

Put plainly, the nerve offers a way into the brain's own regulating systems without opening the skull.

One small branch of the vagus supplies the skin of the outer ear (Butt 2020). That is the branch the ear stimulator uses.

What the ear stimulator does with its current

Stimulating the vagus through the skin to treat seizures isn't new. In the 1880s James Leonard Corning stimulated the vagus through the skin of the neck to treat seizures, combined with pressure on the neck arteries; it caused slow heart rates, dizziness and fainting, and was abandoned (Lanska 2002).

The tVNS E places a small electrode over that ear branch, in the upper hollow of the ear's bowl, the cymba conchae (the anatomy is in my earlier article on epilepsy surgery). It delivers pulses 25 times a second, in cycles of 28 seconds on and 32 seconds off, at a current setting felt as a gentle tingle, never as pain. The only thing the user can change with the tVNS E device is the current, which has a maximum intensity of 5 mA. In the main European trial of its predecessor, the average setting in the active group was half a milliamp (Bauer 2016).

The brain is reached through the nerve's own signal pathways. For the implant, a recent review of the mechanism puts the weight on exactly the pathway described above: large sensory fibres relaying through the nucleus of the solitary tract, and noradrenaline from the locus coeruleus (Carron 2023). The same review deliberately leaves out the ear device: there isn't yet enough data to say it works the same way. I personally believe it is quite likely but a belief is not evidence.

Its effect on the heart needs a word of its own. With the implanted stimulator, whose wire sits on the nerve itself, testing the lead during the operation has slowed or briefly stopped the heart in about 1 in 875 cases (Asconapé 1999). For ear stimulation, the largest safety review found no severe heart problems attributed to it (Kim 2022). Even so, anyone with a heart rhythm problem should speak to their doctor first. The instructions for use state that people with active implants, such as a cardiac pacemaker, should not use tVNS E.

What happened when people with epilepsy used it

In the main European trial, 76 adults with drug-resistant epilepsy used the tVNS E's predecessor for 20 weeks at a higher or lower setting. Side effects were "usually mild or moderate": headache, ear pain, skin redness, vertigo, tiredness and nausea. There were four serious adverse events, including one sudden unexplained death in epilepsy in the lower-setting group, assessed as not related to treatment. Seizures in that group rose by an average of 2.9% (Bauer 2016). A 2023 trial of 150 adults, using a different manufacturer's ear device, reported no severe adverse events and no difference in side effects between groups (Yang 2023).

Reviews point the same way. Across 51 studies of 1,322 people stimulated for any condition, the commonest side effects were skin irritation (18%) and headache (3.6%), and of 30 serious adverse events only 3 were judged possibly caused by the stimulation (Redgrave 2018). A review of 10 studies in 350 people with epilepsy found no serious side effects (Lampros 2021), and a review of 177 studies found no difference in side-effect risk from control (Kim 2022). I have not found a single published case of ear stimulation triggering a seizure.

Here I want to be candid about the evidence becayse as is common in our field, most trials are small and short. More than half of ear stimulation studies never mention side effects (Kim 2022). A 2026 sham-controlled trial of another maker's ear device reported no side-effect data, and within it, some individuals had more seizures during active stimulation and some during sham (Hong 2026). And in rats, needle stimulation at 100 Hz at the back of the neck made an induced epilepsy worse, and triggered it in rats that did not have it (Yi 2013). A different animal, technique and site, but enough to stop anyone saying that stimulation near the head can never provoke a seizure.

KEY POINT: Ear stimulation sits squarely in the area the old caution covered, which is why the trials in people with epilepsy matter. They have not reported it making seizures worse. That is reassuring, and it is not absolute proof: many studies did not report side effects at all.

Not every ear clip is the same device

Search for a vagus nerve stimulator and you'll find dozens, from neck devices sold for stress and sleep to ear clips for TENS units, some of them recommended in epilepsy forums. What separates them is not the hardware but what the manufacturer says the device is for.

Under EU and UK law, a product is a medical device when its manufacturer intends it for a particular medical purpose, such as treating a disease. A powered device that delivers energy as treatment is Class IIa by default, and an independent notified body must assess the manufacturer; its four-digit number follows the CE mark. Great Britain accepts devices CE marked under the EU regulation until 30 June 2030, and registration with the MHRA is a listing, not an approval of effectiveness.

Wellness stimulators have not been assessed for any medical purpose, epilepsy included. At least one maker of a wellness neck stimulator advises people with a history of seizures not to use it, and a neck stimulator sold for headache states that its safety has not been evaluated in people with a history of seizures. Many ear clips sold with TENS units sit on the earlobe, the spot researchers use for sham stimulation (designed to be ineffective).

The tVNS E is a Class IIa medical device under the EU regulation, certified for use alongside medication in drug-resistant epilepsy. It's intended purpose is stated as "tVNS E is a non-invasive device for the transcutaneous stimulation of the auricular branch of the vagus nerve at the cymba concha of the left ear"

tVNS E is indicated for patients suffering from depression, epilepsy, chronic migraines and Prader-Willi-Syndrome. For epilepsies the specific indications are a reduction of seizure frequency over a period of 28 days during intervention compared to pre-intervention phase of a minimum 25% after a treatment period of 20 weeks.

Certification means an independent body assessed the manufacturer's evidence for that purpose.

What this does not mean

It doesn't mean a TENS unit on your neck is fine. The NHS advice on TENS was written specifically for TENS, and it still stands.

It doesn't mean the ear device reduces seizures. The main European trial, of its predecessor, missed its primary goal, and in that 2026 sham-controlled trial, seizures fell by 46% with active stimulation and by 49% with sham. I have set out that evidence in the earlier article on epilepsy surgery.

It doesn't mean the device suits everyone. It is for adults, and it must not be used in pregnancy, with an active implant such as a cochlear implant, a pacemaker or an implanted vagus nerve stimulator, with a cerebral shunt, or on sore or broken skin where the electrode sits.

And it doesn't replace an assessment for epilepsy surgery, which NICE advises for everyone with drug-resistant epilepsy.

What I would suggest

First, if you've been told to avoid electrical stimulation, ask your epilepsy team what that advice was about: a TENS unit near the head, or stimulation of any kind.

Second, before you use any device, check that its stated purpose names epilepsy, and take its instructions for use to your neurologist or epilepsy nurse. A wellness label tells you the maker has not and cannot legally claim it's application for epilepsy.

Third, keep a seizure diary for several weeks before you start anything new. It is the only way anyone, you included, will know whether it is helping.

Our tVNS UK service starts with a conversation: whether you have had a surgical assessment, the situations in which the device must not be used, and who your neurologist is. If we think the device is unlikely to help, we say so. We sell the device, and that interest is ours to declare. The details are on the tVNS UK epilepsy page.

Decisions about your treatment belong with you and your clinicians, and nothing we do replaces that relationship. tVNS is not a cure for epilepsy. Nothing is, for most people. The research on vagus nerve stimulation it as an add-on treatment for drug-resistant epilepsy is encouraging but mixed, and the overall quality of evidence is still rated low. Trials show fewer seizures on average, but the pooled results for the number of people who halve their seizures have not yet reached statistical significance. Of course, the risks of using an approved stimulation device such as the tVNS E are low and may prove an attractive option to consider before thinking of a surgical intervention.

Find more details about transcutaneous vagus nerve stimulation and the tVNS E and tVNS R on our specialist website at tVNS-uk.com.

Electricity Can Trigger Seizures, So How Can an Ear Stimulator Treat Them?

Why the TENS box says no

Can electricity cause a seizure? Yes, if it reaches the brain

Why the vagus nerve, of all nerves

What the ear stimulator does with its current

What happened when people with epilepsy used it

Not every ear clip is the same device

What this does not mean

What I would suggest

Further reading

Related articles on our site

Anatomical Concepts.
Every Body Better.

Electricity Can Trigger Seizures, So How Can an Ear Stimulator Treat Them?

Why the TENS box says no

Can electricity cause a seizure? Yes, if it reaches the brain

Why the vagus nerve, of all nerves

What the ear stimulator does with its current

What happened when people with epilepsy used it

Not every ear clip is the same device

What this does not mean

What I would suggest

Further reading

Related articles on our site

Anatomical Concepts.Every Body Better.

Anatomical Concepts.
Every Body Better.