TENS literally means “transcutaneous electrical nerve stimulation”. The Parasym is a TENS device, as is the Medfit and many other brands on the market.

The Parasym appears to be a modified version of the Logistim TENS. I have used both. The Parasym has had its intensity range reduced to enable finer control for the low intensity required for transcutaneous vagus nerve stimulation (tVNS). It is very hard to achieve the correct intensity level on the Logistim. There are other cheap TENS devices which do this much better than the Logistim, including the Medfit.

Another factor to consider is that digital TENS devices are generally accurate. Analogue devices are less so.

 

So provided that you can:

 

– Program the device to the correct settings (Parasym use 20Hz, 200us and a constant/”normal” mode for ME/CFS)

– Control the intensity to the therapeutic level, which is just below the level of tingling

– Deliver the stimulation to the vagus through an appropriate electrode setup

– And the device is accurate…

…you will achieve transcutaneous vagus nerve stimulation.

The other factors to consider are:

 

ASSESSMENT:

 

– If you purchase a Parasym you will have an assessment at the point of purchase to determine if this is safe for you. They also provide after-sales support.

– If you just purchase a standard TENS unit, you will be responsible for seeking medical advice. The Parasym Manual may offer your doctor guidance regarding the factors to consider. https://files8.webydo.com/…/B4104A87-D5D8-0E0B-53F1…

– tVNS is a relatively low-risk therapy, but is not suitable or safe for everyone, as outlined in the Parasym Manual.

 

PROGRAMMING:

 

– Parasym comes pre-set for tVNS. If you purchase a standard TENS device, you will be responsible for the programming.

– Some devices are harder to program than others, and some devices do not even have the capacity to customise settings for tVNS. The Medfit appears to be easy to program and can be customised. There are other brands that may be suitable too.

– If you do not program the device correctly, this may cause harm. If your device has settings that can accidentally be changed without you realising, this may also cause harm.

– “Brain fog” could impair your capacity to do the programming, so please seek assistance from someone to do the programming in this case. THE FACTORY SETTINGS ARE GENERALLY NOT THE CORRECT SETTINGS FOR TVNS.

– Please also be aware that devices that are battery operated often revert to factory settings when you change the batteries. So you will need to re-program this kind of device. This is not an issue with the Medfit as it is rechargeable. The iStim EV-820 is an example of a battery-operated TENS device that holds its setting after battery changes.

 

ELECTRODES:

 

– This is a variable that may impact on the effects of tVNS, and more research is required to determine the optimum location and type of electrode.

– The Parasym clip is not necessarily “better” than other electrodes. Many people struggle to keep the Parasym clip place if they have a small tragus. Also, people with metal sensitivities may react to the gold-plate on the clip surface.

– Other off-the-shelf clips use electro-conductive plastic which eliminates the issue of metal sensitivity. However, they can be painful/uncomfortable to use.

– Clip design is in my view the area that needs the most development. All the existing electrode designs have shortcomings. I’m hopeful that new options will come onto the market to address these issues.

So, in summary, you can achieve tVNS with a Parasym or a cheap TENS device. There are factors that impact whether a TENS device can be setup appropriately for tVNS. To determine whether tVNS is safe and appropriate for you, regardless of the device that you plan to use, please consult your doctor.