This month’s episode of Epilepsy Explained focuses on two neuromodulation devices, Vagus Nerve Stimulation, or VNS, and Deep Brain Stimulation, or DBS. Dr. Taylor Abel, Chief of Pediatric Neurosurgery at the University of Pittsburgh Medical Center Children’s Hospital, answers basic questions about how these devices are used to reduce or control seizures in some people with epilepsy.
In “VNS and DBS Explained”, Dr. Abel answers the following questions.
0:16 What are VNS and DBS and how do they differ from each other?
1:14 Who should consider getting a VNS or DBS device?
2:38 Are there any risks involved with having a VNS or DBS device implanted?
4:04 Are there any potential side effects that people with a VNS or DBS might experience?
5:20 Do these devices require any regular maintenance?
6:54 When and how will I know if the device is making a difference in my seizures?
Video Transcript
What are VNS and DBS and how do they differ from each other?
Dr. Taylor Abel: VNS and DBS are neuromodulation treatments for epilepsy that we use to control difficult to control seizures. VNS stands for vagus nerve stimulation, and it involves placing a stimulator on the vagus nerve that’s then connected to a pulse generator that goes in the chest. And we use this pulse generator to stimulate the vagus nerve with the idea of changing the brain’s activity to treat seizures. DBS stands for deep brain stimulation, and what this involves is rather than trying to change the brain’s activity through stimulating the vagus nerve, we place electrodes directly into the brain into a target within the brain that will stimulate with the goal of reducing or improving seizures.
Who should consider getting a VNS or DBS device?
Dr. Taylor Abel: This is a great question, and to answer this question, I’m first going to take a step back and talk a little bit about who should be considering epilepsy surgery. When we think about epilepsy surgery, we’re really thinking of two different populations of patients. In one category, we’re thinking about patients who have abnormalities in their brain that are causing seizures that we can treat with surgery, and these might be patients with a brain tumor that’s causing seizures or cortical dysplasia. We probably want to be thinking about epilepsy surgery for these individuals. And then the other category is individuals with epilepsy who have what’s called drug resistant epilepsy. This is epilepsy that’s been treated appropriately with two anti-seizure medicines, but there are still seizures that are occurring. And in this instance, when there are two appropriate anti-seizure medicines, the odds of becoming seizure free on an additional medicine are quite low. And so in that instance, we want to start thinking about all types of epilepsy surgery options for which VNS and DBS would be two very important options to consider.
Are there any risks involved with having a VNS or DBS device implanted?
Dr. Taylor Abel: This is a great question and one of the most important things we do as surgeons when we’re talking to families is to consider the trade-offs associated with epilepsy surgery. And so one of the first things we’ll do is actually talk about what the individual patient’s goals are for controlling their seizures, and then talk about what the odds are of a VNS or a DBS achieving those goals. And then after understanding what the potential benefits of the treatment are, then considering some of the potential risks of the treatment. With any type of surgery, there can be risks of a complication. However, both VNS and DBS are considered safe procedures. Probably the most common serious risk of these procedures, as with any implanted device, is the risk of infection. So for either VNS or DBS, there’s about a three to 5% risk of infection that would lead to either requiring antibiotics or even having to have the device removed. So this at the very most would occur in about one in 20 of implantations, so is not very common, but can happen with these procedures.
Are there any side potential side effects that people with a VNS or DBS might experience?
Dr. Taylor Abel: Yes, there can be side effects from both VNS or DBS, and the nature of these side effects really have to do with the nature of stimulating the vagus nerve or the nature of stimulating different brain regions that we might be stimulating with DBS. And so for example, when stimulating the vagus nerve, sometimes there can be increased coughing or hoarse voice or some other symptoms in the throat like that. Oftentimes we’re able to manage those symptoms with changing the stimulation parameters of the VNS. For DBS, there can also be some stimulation side effects, but the nature of these side effects really depends on which part of the brain we’re stimulating with DBS. And so when you’re first turning on a deep brain stimulator, you’ll work closely with your neurologist or whoever’s programming your DBS to see if you’re having any side effects when the stimulation is turned on so that we can fine tune stimulation parameters to reduce those side effects.
Do these devices require any regular maintenance?
Dr. Taylor Abel: This is an important question because both VNS and DBS require regular follow-up with your healthcare team and also regular follow-up with your neurosurgeon. And so in the first year after either VNS or DBS, you’ll have regular follow up with whoever’s programming the device, whether that be a neurologist or a neurosurgeon who will periodically fine tune your stimulation parameters to make sure to slowly increase the parameters to achieve a therapeutic level of stimulation. The other important thing to consider is that both VNS and DBS are operated by batteries, and those batteries will periodically have to be replaced through small battery replacement procedures. And so these procedures typically take 30 minutes or less, and they involve removing the depleted battery and replacing it with a new battery. For VNS, rechargeable batteries are not available, but for DBS, there are rechargeable batteries that are available and can last up to 15 years, which can be particularly important in my field of pediatric neurosurgery where when we place these devices in small children, they will potentially require a lifetime of battery changes.
When and how will I know if the device is making a difference in my seizures?
Dr. Taylor Abel: When we think about the effectiveness of VNS and DBS, we’re typically thinking about reducing the frequency of seizures and reducing the severity of seizures. And so that’s really what we’re looking for with these treatments and neuromodulation treatments like VNS or DBS, we’re trying to change the brain’s activity over time. And so for both of these treatments, they can take up to a year to be effective. And so it’s important to be patient after the stimulation has started and as the stimulation parameters are being increased to see an effect.
Now, that said, sometimes we can see an effective response within just a few months of treatment, but if you’re not seeing it right away, don’t be discouraged. You want to give it some time to be effective. The other thing that’s important to note with neuromodulation treatments or even other types of epilepsy treatments like other types of surgery or medicines, these treatments can be combined for severe epilepsies. And so if you’ve had VNS and it was not effective, you can later consider having DBS. And there have been studies that have shown that this can be effective for specific individuals with epilepsy. And so the bottom line is you want to give it some time, and we’re looking for a reduction in the frequency and severity of seizures.
