Let’s learn all the facts about a brain pattern called VNS Therapy® (vagus nerve stimulation)!
Source: Normal EEG | Springer Publishing (VNS) artifact on the right (arrow) recorded during active stimulation during continuous video-EEG monitoring.
Vagus nerve stimulation (VNS) may prevent or lessen seizures by sending regular, mild pulses of electrical energy to the brain via the vagus nerve. The therapy consists of a device that is implanted under the skin in the left chest area. An electrode or wire is attached to the generator device and placed under the skin. The wire is attached or wound around the vagus nerve in the neck. The device is programmed in the outpatient clinic to deliver pulses or stimulation at regular intervals. A person does not need to do anything for this device to work and is usually unaware of the stimulation. If a person is aware of when a seizure happens, they can swipe a magnet over the generator in the left chest area to send an extra burst of stimulation to the brain.
If the device is delivering a pulse or stimulation during an EEG recording, it can cause an electrical artifact resulting in undesirable signals intermittently that contaminate the EEG or EKG recording. The patient or unshielded electrodes act as an antenna and produce extracerebral sources of artifact like external 60-Hz interference by the induction of magnetic fields created from nearby current flow. It is the current flow that results in electrode depolarization, is amplified by the amplifiers, and creates the resultant “noise.” It is important clinicians recognize these electrophysiological findings as artifacts, to avoid misdiagnosis and facilitate accurate interpretation.
