Non-invasive vagus nerve stimulation (nVNS) is a method of sending gentle electrical signals to the vagus nerve through the skin, avoiding the need for surgery or implants. This technology is based on the principle of neuromodulation, which alters nerve activity with targeted external stimuli. By applying electrical currents to specific points on the body, nVNS provides a user-controlled method for influencing bodily functions regulated by the vagus nerve.
How Non-Invasive Vagus Nerve Stimulation Works
The vagus nerve is the longest cranial nerve and a primary component of the parasympathetic nervous system. It is a major communication pathway that connects the brain to numerous organs, including the heart, lungs, and digestive tract. About 80% of the vagus nerve’s fibers are afferent, meaning they carry sensory information from the body’s organs back to the brain, allowing it to regulate a wide array of involuntary bodily functions.
The mechanism of nVNS relies on the accessibility of vagus nerve branches close to the skin’s surface, particularly in the neck and ear. By placing a device on the skin at these locations, a mild electrical current passes through the tissue to reach the vagal nerve fibers. This external stimulation activates the nerve, causing it to send signals along its pathways to the brainstem.
Once these signals reach the brainstem, they are relayed to other brain regions. This process can influence the release of neurotransmitters, such as serotonin and norepinephrine, which are involved in mood regulation and seizure control. Stimulating the vagus nerve also triggers the cholinergic anti-inflammatory pathway, a mechanism that helps reduce systemic inflammation. This modulation of neurotransmitters and inflammation gives nVNS its therapeutic potential.
Types of Non-Invasive VNS Devices
Non-invasive vagus nerve stimulation devices are categorized by the location where they are applied. The two main forms are transcutaneous cervical VNS (tcVNS), which targets the vagus nerve in the neck, and transcutaneous auricular VNS (taVNS), which stimulates a branch of the vagus nerve in the ear. Each device type has a specific design for delivering electrical stimulation to the intended nerve fibers.
Devices for tcVNS are handheld and placed against the side of the neck. A well-known example is the gammaCore device. Using it involves applying a conductive gel and pressing the device against the skin over the carotid artery, where it delivers a pre-programmed cycle of electrical stimulation for a few minutes.
In contrast, taVNS devices are designed to be worn on or in the ear, resembling earpieces or small headphones. These devices have electrodes that contact specific areas of the outer ear, such as the cymba conchae or the tragus, which are innervated by the auricular branch of the vagus nerve. An example is the Parasym device, which sends signals to the brainstem in a manner comparable to cervical stimulators.
Medical and Wellness Applications
The applications for nVNS range from clinically approved medical treatments to general wellness uses. The strongest evidence for nVNS is in headache management. The Food and Drug Administration (FDA) has cleared specific nVNS devices for the acute treatment of pain associated with migraine and episodic cluster headaches in adults by blocking pain signals.
Beyond FDA-cleared uses, nVNS is being investigated for a wide range of other conditions, including treatment-resistant depression, anxiety, and post-traumatic stress disorder (PTSD). Studies suggest nVNS may help modulate mood and reduce anxiety by influencing neurotransmitter activity. There is also interest in its anti-inflammatory effects for conditions like rheumatoid arthritis and inflammatory bowel disease.
The technology is also being studied for its role in stroke rehabilitation. When paired with physical therapy, nVNS may help create new neural pathways in the brain, potentially improving motor function. In addition to these medical investigations, a market has emerged for direct-to-consumer wellness devices that claim to help with stress reduction, improved focus, and better sleep.
Acquiring and Using a Device
The process for obtaining an nVNS device depends on its classification. Devices cleared by the FDA for treating medical conditions like migraine require a prescription from a healthcare provider. This ensures a medical professional has determined that nVNS is an appropriate treatment for the patient’s condition.
A growing number of nVNS devices are also available over-the-counter for general wellness purposes, such as stress relief and relaxation. While more accessible, consulting with a healthcare provider is still advisable, especially for individuals with pre-existing health conditions or who are pregnant. A doctor can help rule out contraindications, such as the presence of an implantable medical device like a pacemaker.
Typical use of an nVNS device involves daily sessions. For example, a preventative treatment for migraine might involve two-minute stimulation sessions performed twice a day, while acute treatment is used as needed. Side effects are generally mild and temporary, and can include skin irritation at the application site, a tingling sensation, dizziness, or a change in voice. These effects tend to diminish as the user becomes accustomed to the sensation.