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 radio frequency (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.
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.