Vagus nerve stimulation (VNS Therapy®) is designed to prevent seizures by sending regular, mild pulses of electrical energy to the brain via the vagus nerve. These pulses are supplied by a device something like a pacemaker.
- The VNS device is sometimes referred to as a "pacemaker for the brain." It is placed under the skin on the chest wall and a wire runs from it to the vagus nerve in the neck.
- The vagus nerve is part of the autonomic nervous system, which controls functions of the body that are not under voluntary control, such as the heart rate. The vagus nerve passes through the neck as it travels between the chest and abdomen and the lower part of the brain.
How is VNS used?
- The neurologist (or licensed professional) programs the strength and timing of the impulses according to each patient's needs. The settings can be programmed and changed by placing a wand over the generator on the left side of the chest. The wand is connected to a handheld computer.
- For all patients, the device is programmed to go on (give stimulation) for a certain period (for example, 7 seconds or 30 seconds) and then to go off (stop stimulation) for another period (for example, 14 seconds or 5 minutes). The device is set to give stimulation at regular intervals during the day, usually with 30 seconds of stimulation alternating with 5 minutes of no stimulation. The patient is usually not aware that it's operating.
- Holding a special magnet near the implanted device (generator) triggers the device to deliver another burst of stimulation, outside of the programmed intervals. For people with warnings (auras) before their seizures, activating the stimulator with the magnet when the warning occurs may help to stop the seizure.
- Settings (also called stimulation parameters) set by the neurologist typically include a stimulation amplitude of 1.0 to 3.0 mA (milliamperes), a stimulation frequency of 20 - 30 Hz (hertz), and a pulse width of 130 - 500 microseconds. By adjusting these settings, the doctor not only may be able to control more of the patient's seizures, but often can also relieve side effects. One study, for instance, found that changing the pulse width eliminated pain that some patients were experiencing.
- The battery for the stimulator lasts approximately 5-10 years, depending on the settings used.
However, Soren is not getting the VNS implanted today. That will hopefully happen some time in May. Today I'm taking him for a 24 EEG telemetry at Children's Hospital. Once again, I shall let the good folks at epilepsy.com explain this...
What is a Video EEG test?
A Video EEG test records your brainwaves on an EEG and a video of what is going on at the same time. The purpose is to be able to see what is happening when you have a seizure or event and compare the picture to what the EEG records at the same time. Sounds that occur during the testing are also recorded - this can pick up if a person talks or makes sounds during an event. By doing this, doctors reading the EEG can tell if the seizure or event was related to the electrical activity in the brain. If so, we'd call this an epilepsy seizure.
- Video-EEG is most helpful to determine if seizures with unusual features are actually epilepsy, to identify the type of seizures, and to pinpoint the region of the brain where seizures begin. Locating the region precisely is essential if epilepsy surgery is being considered.
- Other names for Video EEG tests include: EEG telemetry, EEG monitoring, or Video EEG monitoring. Usually these terms mean the same thing.
Then next week Soren will have an MRI of his brain done. Now, Soren has had EEG telemetries and MRIs done before, but it's been a number of years. The neurologist in monitoring Soren's VNS has never seen Soren's seizure activity. And getting a more up-to-date look at his brain development is good. Plus, it's much harder to do an MRI once the VNS put in due to the magnetism.
So, as I stated above, today is the start of the adventure. I'm preparing for our 24 hour hospital stay--bringing Soren's laser lights so he has something to look at, my computer for some writing and to catch up on "The Blacklist," old People magazines for some light reading, and my ukulele to entertain myself and Soren. On Wednesdays, the Farmer's Market comes to Children's Hospital, so I'm going to get some hummus and pita chips for snacking.
Then I'll wait for my son to have seizures over the next 24 hours, which in this instance is exactly what we want.
Wish us luck!