Monday, March 12, 2007

Survivor’s Guide to VNS: Part 10 – Effective Settings

The Goal
The object of the settings is to cause your nerve to send signals to the brain. The electrical energy sent to the nerve from the generator has to be enough to cause the nerve to “fire”. Kind of like a spark plug. One key thing to understand is that not everyone’s nerve NEEDS the same amount of electricity in order to cause it to send a signal. This is why the settings need to be adjusted for each person individually.

Unfortunately, there is no real clear chart that says that indicates what setting each person needs. Fortunately, there are some studies that rule out various settings.

Signal Frequency
Studies have been done that show that stimulation to the Vagus Nerve at frequencies of 10 Hz or less do not cause the nerve to send signals. So, your signal frequency should be around 20 to 30 Hz. I keep mine at 20.

Signal ON Time
The Signal On Time should be set to 30 seconds. Although I have seen a few studies that have set it to shorter On Times, the standard is 30. I would keep it at that.

Signal Off Time
I read about a lady who’s psych dr. set her off time to 3 hours! Because it went off so infrequently, she was completely stunned whenever it went off. Don’t let that happen to you. This setting should be between 5 minutes and 1.1 minutes. In addition, the Signal Off Time should not be less than the Signal On Time. I have mine set to 1.1 minutes off.

Output Current & Pulse Width
The two settings that seem to have the most direct impact on side effects and efficacy are the Output Current (OC) and the Pulse Width (PW). One study I have read shows a direct correlation between the two settings and age.

A typical setting that doctors use will be 500 PW and then increase the OC in .25 mA intervals until it gets to 1 or 1.5 mA… regardless of the person or what side effects it causes. Don’t let them adjust your settings this way! Each person is different and needs different settings.

Start with a 130 PW and .25 OC. This is as low as it goes. If you can’t feel it, bump up the PW or the OC one notch until it gets a bit aggravating. Don’t let them put you on a setting where it physically hurts or it causes you to choke. When you get it adjusted up, the VNS should be annoying, not painful.

Remember that the goal is to get your nerve to activate and send a signal to the brain. Start by slowly increasing your settings. Each time, increase them only to the point where the side effect is annoying, not painful or choking to the point of not breathing during activation. Over time, the annoyance will reduce and hopefully within a few days, you will barely notice it.

It will take a while before you start to get any results… if it works for you. You may even have to wait a whole year. Slowly increase your settings over the first few months. Make note of how many seizures you have. The VNS can cause some people to have more seizures. I found that at a higher pulse width and current, I had more seizures. When I lowered it, I had less.

Greater Efficacy over Time
The VNS has somewhat reduced the number of seizures I have, but has definitely reduced the intensity of my seizures. For example, I had a Tonic-Clonic seizure last month, and for the first time, I did not stop breathing. My recovery time after the seizure was immensely reduced. Instead of days or hours of recovery time, I was able to function after only an hour of rest. Amazing.


Honeybunny25 said...

Thank you so much for this honest explanation of all the pros and cons of having vns therapy. It’s made me realise how little they tell you and I haven’t been able to access this kind of info on other sites. I've had mine implanted since August last year and I've only had it increased three times because it was causing me pain each time. The pain eases after a week or so, but it has meant that I haven’t had it increased as much as I should have done. Only three times in over a year. Now I know about all the different settings, (not just the one setting they tell you about) I’m going to go back an get them to adjust them, so I wont be in pain each time. I just thought it was a side effect I had to put up with. Thanks for the info.

Paula said...

Thank you. Our son had his vns implanted 6 months ago and is at 1mA 4.5mins off and 0.5min on. We are back to have it adjusted in November and so your information has been useful. Kind Regards, Paula