There is lots of buzz about the vagus nerve at the moment, with interest in how, by stimulating it, it can alleviate depression, help with stroke rehabilitation, treat headaches and migraines and control epilepsy. It is even showing promise as a treatment for obesity, rheumatoid arthritis and other inflammatory disorders.
Extending from the brain to the gut, the vagal nerves are a key part of the parasympathetic nervous system, which is responsible for the body’s rest and digestion response. There are various devices designed for stimulation, but this is an area of healthcare where New Zealand seems to be lagging behind.
Now, the Epilepsy Waikato Charitable Trust is petitioning the government to fully fund vagus nerve stimulation for New Zealanders with hard-to-treat epilepsy. About half of epilepsy sufferers manage to control their seizures well with medication; for others, surgery may be an option.
“But there are people who keep having seizures despite taking multiple drugs and some of them will benefit from vagus nerve stimulation,” says Auckland neurologist Peter Bergin. “The group who benefit most are those who have drop attacks, so they’ll suddenly fall during seizures which puts them at risk of injury.”
To treat epilepsy, a device that looks a little like a heart pacemaker is implanted under the left collarbone. A lead connects this to the vagus nerve in the left side of the neck. The device electrically stimulates the nerve regularly, day and night, for short intervals. In response, the vagus nerve sends messages to the brain stem, modulating its circuitry and preventing or reducing the severity of seizures.
“It’s not a miracle and doesn’t work for everyone, but it can result in a significant improvement for some people,” says Bergin. “Not many will stop having seizures completely but if they get sufficient warning, recognising the signs of a seizure before it progresses too far, they can activate the system by swiping a magnet over the device and this may terminate the seizure or at least make it more gentle than usual.”
Some of the newer devices will also detect a sudden increase in heart rate, which can happen at the start of a seizure, and respond by stimulating the nerve.
Side effects of the therapy tend to be temporary and are usually hoarseness and changes to the voice, headaches and cough. Compared with the toll that seizures can take on a person’s quality of life – affecting education, work and mental health – these are manageable.
The barrier is that vagus nerve stimulators and the surgery to implant them are expensive. The parliamentary petitions committee heard in August the device costs $30,000 plus $20,000 for the surgery.
Although some children have been able to access therapy here, Epilepsy New Zealand says adult sufferers have needed to travel overseas, such as to Australia or the US, where it is more commonly used.
Even an attempt to run a clinical trial in Auckland to assess the benefits of vagus nerve stimulation and its impact on injuries and hospital admissions has been thwarted due to lack of funding.
“But there are already some good-quality clinical trials that show these devices can make a real difference,” says Bergin. “I look after dozens of people who have tried more than 10 drugs and still have frequent seizures. Some of them will undoubtedly improve if they are given a vagus nerve stimulator and their quality of life will be better than it is now.”
In the US, implantable vagus nerve stimulators are also approved to treat stroke. If a patient has problems using their hand or arm after a stroke, the stimulation can help create new pathways in the brain that help them regain function. Other devices that don’t require surgery are approved in the US to treat cluster headaches and migraines. These stimulate the nerve when held against the neck, reducing the attack’s intensity.
Potentially, all of us can benefit from activating the vagus nerve because it helps calm the stress response and reduce inflammation. Cold-water therapy is one way of doing this, along with more pleasant options such as massage, laughter and singing.
