Stimpod Nerve Stim (NMS)

How does the Stimpod NMS460 work?

Non-Invasive Pulsed Radio Frequency (PRF)
The therapeutic effect of the NMS460 waveform is based on the cellular metabolic activity observed when a neuropathic nerve is subjected to electromagnetic effects caused by pulsed radiofrequency (PRF). This cellular metabolic activity seems to change the characteristics of the nerve, which in many cases causes the nerve to recover back to its normal function.

Typically there are four phases associated with a pulsed radiofrequency procedure:
• A stunning phase, which provides immediate relief.
• Occasionally there may be a phase of post-procedure discomfort.
• A phase of beneficial clinical effect.
• A possible phase of recurrence of pain or paralysis.

Nerve location using nerve stimulation

As with invasive PRF procedures, one big challenge is to locate nerves using PRF.
The NMS460 delivers this PRF waveform by means of a non-invasive probe, which is applied transcutaneously to the affected nerve.
Many peripheral nerves are combined motor/ sensory nerve bundles and have some locations where they are superficial, which makes them easy to locate using simple nerve stimulation techniques.The Stimpod NMS460 combines the PRF waveform with a monophasic square wave, which is used to locate the nerve. When the nerve mapping probe is close enough to a motor nerve and the current is set appropriately the stimulation will cause a fasciculation of the relevant muscle. The closer the probe is positioned to the nerve the stronger the fasciculation will be.
In situations where pure sensory nerves are to be located the user will need to rely on the feedback of the patient. The closer the nerve mapping pen gets to the sensory nerve the stronger the sensation will be.

Assisting with diagnosis

The shape of the applied waveform is such that it creates discomfort in a healthy sensory nerve, however, the sensation to a neuropathic nerve is usually very comfortable. This feature further allows the physician/ therapist to make an accurate diagnosis of the affected nerve.

Measurable progress

The recovery of sensory nerves can be measured by the comfort level experienced at different levels of intensity of the stimulus. It may be comfortable to treat a neuropathic nerve at a current of around 30 mA at the first treatment, however, as the nerve recovers the current intensity would have to be reduced in subsequent treatments in order to maintain a comfort level for the patient. This provides the physician/ therapist with a quantifiable means to measure progress. The same goes for motor nerves, but rather than the sensation, a progress judgment can be made on the intensity level of the fasciculation.

How to treat with the NMS460 – Step by Step. 

Treatment with the NMS460 starts by locating the affected nerve. Through clinical evaluation, you can identify the nerve that is responsible for the symptoms, like chronic pain, nerve palsy etc.
Once the nerve is located, use your anatomical knowledge to localize the most superficial aspects of the nerve.
Depending on the condition, you will either (A) treat a motor nerve or a sensory nerve within a combined sensory or motor nerve bundle, or (B) treat a pure sensory nerve.

A. Treatment steps for motor nerves or sensory nerves within a combined sensory or motor nerve bundle
1. Switch the Stimpod NMS460 on.
2. Switch the pulse width to 0.1ms by pressing the Pulse Width Button.
3. Adjust the frequency to 2 Hertz by pressing the Hz Button.
4. Apply the reference electrode to the patient distally from the targeted treatment area.
5. Apply conductive gel to the targeted treatment area.
6. Press the Center Button.
7. The display will now indicate an open circuit and the LED will be flashing red. The countdown timer will also be initiated (default 10 minutes).
8. Apply the nerve treatment probe to the area that was previously anatomically identified as the most superficial area of the targeted nerve.
9. When the treatment probe makes contact with the skin, the open circuit warning will be replaced with a display of the average current delivered. The LED will now be flashing green and you will also hear a beeping sound.
10. Using the Clickwheel, slowly increase the current up to a level that is comfortable for the patient.
11. Move the nerve treatment probe around until a fasciculation is caused by the muscle innervated by the targeted nerve. (Depending on how deep the nerve is, 6-12mA may be necessary to elicit a fasciculation.)
12. Keep moving until the fasciculation elicited is at its maximum strength. You have now located the most superficial aspect of the targeted nerve.
13. Proceed to increase the current intensity to the maximum that the patient can tolerate.
14. Keep the probe on this spot for 5-10 minutes.
15. It may be comfortable for the patient to increase the current after 1-2 minutes due to sensory nerve accommodation to the stimulus.
16. If the patient can comfortably tolerate 30mA at a 0.1ms pulse width, change the pulse width to 0.2ms and turn the current down to 15mA. Proceed to increase the current to a level that the patient can tolerate.

B. Treatment of pure sensory nerves
1. Repeat steps 1-10 as above.
2. Move the nerve treatment probe around until the patient confirms a sensation.
3. Keep moving the probe until the sensation is at its maximum strength. You have now located the most superficial aspect of the targeted sensory nerve.
4. Proceed to increase the current intensity to the maximum that the patient can tolerate.
5. Keep the probe on this spot for 5-10 minutes.
6. It may be comfortable for the patient to increase the current after 1-2 minutes due to sensory nerve accommodation to the stimulus.
7. If the patient can comfortably tolerate 30mA at a 0.1ms pulse width, change the pulse width to 0.2ms and turn the current down to 15mA. Proceed to increase the current to a level that the patient can tolerate.
Notes

• When you are stimulating a neuropathic sensory nerve that is causing chronic pain, the sensation is often perceived by the patient as being very comfortable, as opposed to when a normal sensory nerve is stimulated, which could be perceived as feeling more prickly (like a pinprick).
• If there are multiple nerves or nerve branches affected, you should treat each one of them for 5-10 minutes.